Ask the Experts: All Questions

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Results (1316)

Yes. However, data are limited on the safety and immunogenicity effects when Heplisav-B or PreHevbrio is interchanged with HepB from other manufacturers. When feasible, the same manufacturer’s vaccines should be used to complete the series. However, vaccination should not be deferred when the manufacturer of the previously administered vaccine is unknown or when the vaccine from the same manufacturer is unavailable.

The 2-dose (4 weeks apart) HepB series only applies when both doses in the series consist of Heplisav-B. Series consisting of a combination of 1 dose of Heplisav-B and a vaccine from a different manufacturer should consist of 3 total vaccine doses and should adhere to the 3-dose schedule minimum intervals of 4 weeks between dose 1 and 2, 8 weeks between dose 2 and 3, and 16 weeks between dose 1 and 3. Doses administered at less than the minimum interval should be repeated. However, any series containing 2 doses of Heplisav-B administered at least 4 weeks apart is valid, even if the patient received a single earlier dose from another manufacturer.

Last reviewed: July 21, 2023

Yes. If patients have an uncertain vaccination history and their records are not readily obtainable, you should administer the recommended doses: PCV20 alone or PCV15 followed by PPSV23 one year later. Extra doses will not cause harm to the patient. Per the CDC’s “General Best Practices for Immunization Guidelines”, self-reported doses of influenza and PPSV23 are acceptable. Therefore, if a patient remembers receiving PPSV23, it is acceptable to provide only one dose of PCV20 or one dose of PCV15.

Last reviewed: April 5, 2024

The minimal intervals for the 3-dose HepB vaccines are at least 4 weeks between doses #1 and #2, at least 8 weeks between doses #2 and #3, and at least 16 weeks between doses #1 and #3. Since in your cases 16 weeks or more have elapsed since dose #1, you should schedule dose #3 to be given 8 weeks after dose #2. It is not necessary to restart the series because of an extended interval between doses, no matter how long.

Last reviewed: July 21, 2023

Recipients of mRNA COVID-19 vaccines often experience local (e.g., pain, swelling, redness at the injection site, localized swollen lymph nodes in the armpit of the vaccinated arm) or systemic (e.g., fever, fatigue, headache, chills, body and joint aches) post-vaccination symptoms. Depending on vaccine product (Pfizer-BioNTech vs. Moderna), age group, and vaccine dose, in clinical trials, approximately 80–91% of vaccinated people develop at least one local symptom and 55–91% develop at least one systemic symptom following vaccination.

Most systemic post-vaccination symptoms are mild to moderate in severity, occur within the first three days of vaccination, and resolve within 1–3 days of onset.

Among children ages 6 months through 4 years (Pfizer-BioNTech) or 6 months through 5 years (Moderna), pain or tenderness at the injection site was the most frequent local reaction. The most common systemic symptom in older children was fatigue; in younger children (ages 6 through 23 months), irritability/crying and drowsiness/sleepiness were most common. Most systemic symptoms were mild to moderate in severity, typically began 1 to 2 days after vaccination, and resolved after 1 to 2 days.

Last reviewed: March 19, 2024

The guidance for handling after reconstitution is the same for both brands of MMR vaccine (MMRII and Priorix). It is preferable to administer MMR immediately after reconstitution. If not used immediately, the reconstituted vaccine should be store refrigerated (2°C to 8°C [36°F to 46°F]) until use. If reconstituted MMR is not used within 8 hours, it must be discarded.

Last reviewed: June 19, 2023

Tdap is an inactivated vaccine and may be given at the same prenatal visit with RhoGam. For more information on this topic, including the timing for the use of other vaccines with regards to RhoGam, see ACIP’s “General Best Practice Guidelines” for Immunization at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html for more information on this issue.

Last reviewed: March 31, 2022

In clinical trials of Novavax COVID-19 Vaccine, pain or tenderness at the injection site was the most frequently reported local reaction among vaccine recipients; redness and swelling were reported less frequently. Fatigue, headache, and muscle pain were the most commonly reported systemic reactions. Most symptoms were mild to moderate in severity and resolved within 1 to 3 days. Overall, symptoms were more frequent in people ages 18 through 64 years compared to people ages 65 years and older and more frequent after dose 2 than dose 1.

Last reviewed: March 19, 2024

No. However, this person should receive PCV15 or PCV20 one year after PPSV23 if he has no history or an unknown history of receiving a pneumococcal conjugate vaccine in the past.

Last reviewed: April 5, 2024

Yes. Many years of experience with Engerix-B and Recombivax HB brands of HepB vaccines indicate no apparent risk for adverse events to a developing fetus. Current HepB products contain noninfectious hepatitis B surface antigen (HBsAg) and should pose no risk to the fetus. If not vaccinated, a pregnant person may contract an HBV infection during pregnancy, which might result in severe disease for the newborn.

Available human data on Heplisav-B and PreHevbrio administered during pregnancy are insufficient to assess vaccine-associated risks in pregnancy. For this reason, until safety data are available for Heplisav-B or PreHevbrio, providers should continue to vaccinate people needing HepB during pregnancy with either Engerix-B or Recombivax HB. Pregnancy testing prior to vaccination is not recommended.

Mothers who breastfeed their babies and need HepB can be vaccinated. Although data are not available to assess the effects of Heplisav-B and PreHevbrio on breastfed infants or on maternal milk production and excretion, there is no theoretical risk to the infant and vaccination with any HepB product is acceptable.

Last reviewed: July 21, 2023

A family history of a neurologic disorder or reaction to a pertussis-containing vaccine is not a contraindication to vaccination of this child. The child should receive additional DTaP doses as indicated in the catchup schedule.

Last reviewed: March 31, 2022

Only the diluent supplied with the MMR vaccine should be used to reconstitute any vaccine. A vaccine reconstituted with the incorrect diluent should be repeated.

Last reviewed: June 19, 2023

CDC discourages the practice of prefilling vaccine into syringes for several reasons, including:

  • The increased possibility of administration and dosing errors
  • The increased risk of inappropriate storage temperature
  • The probability of bacterial contamination
  • The probability of reducing the vaccine’s potency over time

Prefilling vaccine into syringes also violates basic medication administration guidelines, which state that an individual should administer only those medications he or she has prepared and drawn up.

Although pre-drawing vaccine is discouraged, a limited amount of vaccine may be pre-drawn in a mass-immunization clinic setting under the following conditions:

  • Only a single type of vaccine (for example, influenza) is administered at the mass-immunization clinic setting
  • Vaccine is not drawn up in advance of its arrival at the mass-vaccination clinic site
  • These pre-drawn syringes are stored at temperatures appropriate for the vaccine they hold
  • No more than 1 vial or 10 doses (whichever is greater) is drawn into syringes
  • Clinic staff monitor patient flow carefully and avoid drawing up unnecessary doses or delaying administration of pre-drawn doses

At the end of the clinic day, all remaining vaccine in syringes prefilled by staff should be discarded.

Last reviewed: September 10, 2023

It is preferable that the person planning to have the procedure be protected from pneumococcus at the time of the surgery; if possible, administer the appropriate vaccine at least two weeks in advance of the splenectomy or cochlear implant. If the procedure is done on an emergency basis, vaccinate as soon as possible after surgery. Adults who have not previously received any pneumococcal vaccine should receive either PCV20 alone or PCV15 followed by PPSV23 at least 8 weeks later.

Recommendations for vaccination of a child in this situation depends on the child’s age and pneumococcal vaccination history (number of doses and types of vaccine(s) received). To evaluate the specific needs of the child, see CDC’s guidance at www.cdc.gov/vaccines/vpd/pneumo/hcp/who-when-to-vaccinate.html or Immunize.org’s Recommendations for Pneumococcal Vaccination of Children and Teens at www.immunize.org/wp-content/uploads/catg.d/p2016.pdf.

Last reviewed: April 5, 2024

Vaccinating people against influenza who have recently tested positive for COVID-19 involves multiple considerations, such as whether vaccinating them could expose others to COVID-19, how sick they are, their risk for severe influenza illness, the ability to vaccinate at a later date, and the desire to avoid confusing postvaccination symptoms with those of COVID-19. Usually, people who are infectious should not be brought to a vaccination setting if doing so could expose others to COVID-19. Any moderate or severe acute illness is a precaution to influenza vaccination: vaccination should generally be deferred until recovery. For people with mild or asymptomatic COVID-19, delaying vaccination might be considered to avoid confusing COVID-19 symptoms with postvaccination reactions.

CDC may continue to modify recommendations for vaccination of this population.

Last reviewed: September 10, 2023

This depends on the contraindication or precaution the person had to DTaP.

The contraindications are (1) severe allergic reaction (e.g., anaphylaxis after a previous dose or to a vaccine component) and (2) encephalopathy within 7 days of a previous dose of DTaP or DTP; in these cases, give Td instead of Tdap.

The precautions for which Tdap vaccination may be delayed or for which the balance of individual risks and benefits should be weighed are

  • Moderate or severe acute illness (defer until recovered);
  • History of an Arthus-type hypersensitivity reaction following a previous dose of tetanus or diphtheria toxoid-containing vaccines, including MenACWY-D or MenACWY-TT (Menactra or MenQuadfi, Sanofi Pasteur) (defer vaccination until at least 10 years have elapsed since the last tetanus-toxoid-containing vaccine);
  • Guillain-Barré syndrome (GBS) 6 weeks or sooner after a previous dose of tetanus toxoid-containing vaccine; and
  • Progressive or unstable neurologic disorder, uncontrolled seizures or progressive encephalopathy until a treatment regimen has been established and the condition has stabilized.

ACIP has published a Guide to Vaccine Contraindications and Precautions in its “General Best Practice Guidelines for Immunization”, available at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/contraindications.html.

Last reviewed: March 31, 2022

All HCP, including trainees, who have a high risk of occupational percutaneous or mucosal exposure to blood or body fluids (for example, HCP with direct patient contact, HCP at risk of needlestick or sharps injury, laboratory workers who draw, test or handle blood specimens) should have postvaccination testing for antibody to hepatitis B surface antigen (anti-HBs). Postvaccination testing should be done 1–2 months after the last dose of vaccine. Postvaccination testing for individuals at low risk for mucosal or percutaneous exposure to blood or body fluids (for example, public safety workers and HCP without direct patient contact) likely is not cost-effective; however, those who do not undergo postvaccination testing should be counseled to seek immediate testing if exposed.

Last reviewed: July 21, 2023

Inactivated influenza vaccines are not known to cause false positive nasal swab tests. The results may indicate real infections; however, false positive test results are possible with rapid tests, and these are more likely to occur if the tests are done when influenza prevalence in the area is low. For more information regarding interpretation of rapid influenza tests see www.cdc.gov/flu/professionals/diagnosis/rapidlab.htm.

Last reviewed: September 10, 2023

There are two options for healthcare professionals who test negative after completing their first HepB series. The first option is to give one dose of HepB, then retest for anti-HBs. If the result is positive, the person should be considered immune. If negative, the person should receive the remaining doses in the series, and then retest for anti-HBs. If the result is positive, the person should be considered immune. If negative, the person should be tested for HBsAg and total anti-HBc to determine their HBV infection status.

People who test negative for HBsAg and total anti-HBc should be considered vaccine non-responders and susceptible to HBV infection. They should be counseled about precautions to prevent HBV infection and the need to obtain hepatitis B immune globulin (HBIG) prophylaxis for any known or likely exposure to HBsAg-positive blood. Those found to be HBsAg negative but total anti-HBc positive were infected in the past and require no vaccination or treatment. If the HBsAg and total anti-HBc tests are positive, the person should receive appropriate counseling for preventing transmission to others as well as referral for ongoing care to a specialist experienced in the medical management of chronic HBV infection. They should not be excluded from work.

The second option is to repeat the 2- or 3-dose series (depending on vaccine brand) and test for anti-HBs 1–2 months after the final dose of the repeat series. Heplisav-B or PreHevbrio may be used for revaccination following an initial HepB series that consisted of doses from a different manufacturer. Heplisav-B or PreHevbrio may also be used to revaccinate new healthcare personnel (including the challenge dose) initially vaccinated with a vaccine from a different manufacturer in the distant past who have anti-HBs less than 10 mIU/mL upon hire or matriculation.

If the test is still negative after a second vaccine series, the person should be tested for HBsAg and total anti-HBc to determine their HBV infection status. People who test negative for HBsAg and total anti-HBc should be considered vaccine non-responders and susceptible to HBV infection. They should be counseled about precautions to prevent HBV infection and the need to obtain hepatitis B immune globulin (HBIG) prophylaxis for any known or likely exposure to HBsAg-positive blood. Those found to be HBsAg negative but total anti-HBc positive were infected in the past and require no vaccination or treatment. If the HBsAg and total anti-HBc tests are positive, the person should receive appropriate counseling for preventing transmission to others as well as referral for ongoing care to a specialist experienced in the medical management of chronic HBV infection. They should not be excluded from work.

The choice of option 1 and option 2 should be based on epidemiologic considerations and likelihood that the patient is HBsAg positive, since there is a delay in option 1 in determining HBsAg status.

Last reviewed: July 21, 2023

Controlled epilepsy is not a contraindication to receipt of Tdap. To review the true contraindications and precautions to vaccination, consult the appendix of the CDC Recommended Child and Adolescent Immunization Schedule (www.cdc.gov/vaccines/schedules/hcp/imz/child-adolescent.html). CDC also makes this information available at www.cdc.gov/vaccines/hcp/acip-recs/general-recs/contraindications.html.

Last reviewed: February 19, 2024

For immunocompetent HCP, periodic testing or periodic boosting is not needed. Postvaccination testing (anti-HBs) should be done 1–2 months after the last dose of the HepB series. If adequate anti-HBs (at least 10 mIU/mL) is present, nothing more needs to be done. This information should be made available to the employee and recorded in the employee’s health record.

Last reviewed: July 21, 2023

All children with risk factors for pneumococcal disease or its complications should be vaccinated on time with either PCV15 or PCV20. High-risk children who complete the pneumococcal vaccination schedule without a dose of PCV20 will require additional pneumococcal vaccination. The vaccination needed after completion of the routine series (with PCV13, PCV15, or PCV20) depends on the pneumococcal vaccine product available, the child’s age, specific type of risk factor, and past pneumococcal vaccination history.

There are four resources that can help you determine what pneumococcal vaccinations are recommended for a specific high-risk child:

Last reviewed: April 5, 2024

Vaccine safety monitoring in the United States indicated an increased risk of GBS within 42 days of vaccination with the Janssen COVID-19 Vaccine, with the highest risk among people ages 40 through 64. Most reports were in males. Janssen COVID-19 Vaccine is no longer available in the United States.

Any FDA-authorized or FDA-licensed updated (2023–2024 Formula) COVID-19 vaccine may be given to individuals with a history of GBS.

Last reviewed: March 19, 2024

An infant who experiences an afebrile seizure following a dose of DTaP requires further evaluation. An infant with a recent seizure or an evolving neurologic condition should not receive further doses of DTaP or DT until the condition has been evaluated and stabilized. Other indicated vaccines may be administered on schedule. To assure that the child is at least protected against tetanus and diphtheria, the decision to give either DTaP or DT should be made no later than the first birthday.

Last reviewed: March 31, 2022

IIV should be administered in the anterolateral thigh muscle of an infant or young child. IIV and RIV (approved for people age 18 years and older) should be administered in the deltoid muscle of an older child, adolescent, or adult. The anterolateral thigh muscle can also be used for an older child, adolescent, or adult if necessary. It is critical that intramuscular influenza vaccine be injected into a muscle. Influenza vaccination season is an opportune time to review proper intramuscular injection techniques with your staff. Immunize.org has prepared a printable document on how to administer intramuscular vaccine injections (available at www.immunize.org/catg.d/p2020.pdf) that can be used as a staff training tool.

Last reviewed: September 10, 2023

No. Immunocompetent people known to have responded to HepB vaccination in the past do not require additional passive or active immunization. Postvaccination testing should be done 1–2 months after the original vaccine series is completed. In this scenario, the initial postvaccination testing showed that the healthcare professional was protected. Substantial evidence suggests that adults who respond to a HepB series (anti-HBs of at least 10 mIU/mL) are protected from chronic HBV infection for at least 30 years, even if there is no detectable anti-HBs currently. Only immunocompromised people (for example, dialysis patients, some people living with HIV) need to have anti-HBs testing performed periodically. Booster doses of vaccine to maintain their protective anti-HBs concentrations to at least 10 mIU/mL are recommended for dialysis patients and may be given to some people living with HIV.

Last reviewed: July 21, 2023

No. PPSV23 was never recommended to be given every 5 years. If you see a patient age 65 years or older who, as a result of this practice of repeating doses of PPSV23, has had multiple doses of PPSV23, including any dose administered on or after age 65, evaluate their history of pneumococcal conjugate vaccination. If they have no or unknown history of any doses of PCV, administer either a single dose of PCV20 alone or a dose of PCV15 at least 1 year after their most recent dose of PPSV23.

If they have also received a dose of PCV13 in the past, they may receive a dose of PCV20 at least 5 years after their most recent pneumococcal vaccination based on shared clinical decision-making.

Last reviewed: April 5, 2024

This is not an acceptable practice. Doses of influenza vaccine (or any other vaccine) should never be split into “half doses.” If a “half dose” is administered, it should not be accepted as a valid dose. The second half of the dose may be administered if the error is caught and corrected at that visit; if not, repeat the vaccination as soon as possible with a full age-appropriate dose.

Last reviewed: September 10, 2023

There is no evidence that any of the COVID-19 vaccines affect current or future fertility.

Last reviewed: March 19, 2024

Usually, an “allergy” to tetanus toxoid is anecdotal and not a true anaphylactic reaction to modern tetanus toxoid. Patients often claim to be allergic to tetanus toxoid because of (1) an exaggerated local reaction (which is not an allergy) or (2) a reaction to a tetanus vaccine received many years ago (probably serum sickness from equine tetanus antitoxin). A history of one of these events is not a contraindication to modern tetanus toxoid, Td, or Tdap.

Only an allergist-confirmed severe allergy (e.g., anaphylaxis) to tetanus toxoid should be accepted as a valid contraindication to a modern tetanus-toxoid containing product. A person who has an allergist-confirmed anaphylactic allergy to tetanus toxoid has no recourse for pertussis vaccination because no single-antigen pertussis vaccine is licensed for use in the United States.

Last reviewed: March 31, 2022
Healthcare personnel status Postexposure testing Postexposure prophylaxis Postvaccination
serologic
testing†
Source patient
(HBsAg)		 HCP testing
(anti-HBs)		 HBIG* Vaccination
Documented responder§ after
complete series		 No action needed
Documented nonresponder
after 2 complete series		 Positive/unknown Not indicated HBIG x2 separated
by 1 month		 — No
Negative No action needed
Response unknown after
complete series		 Positive/unknown <10mIU/mL** HBIG x1 Initiate
revaccination		 Yes
Negative <10mIU/mL None
Any result >10mIU/mL No action needed
Unvaccinated/incompletely
vaccinated or vaccine refusers		 Positive/unknown —** HBIG x1 Complete
vaccination		 Yes
Negative — None Complete
vaccination		 Yes

Abbreviations: HCP = health-care personnel; HBsAg = hepatitis B surface antigen; anti-HBs = antibody to hepatitis B surface antigen; HBIG = hepatitis B immune globulin.

* HBIG should be administered intramuscularly as soon as possible after exposure when indicated. The effectiveness of HBIG when administered >7 days after percutaneous, mucosal, or nonintact skin exposures is unknown. HBIG dosage is 0.06 mL/kg.

† Should be performed 1–2 months after the last dose of the HepB vaccine series (and 6 months after administration of HBIG to avoid detection of passively administered anti-HBs) using a quantitative method that allows detection of the protective concentration of anti-HBs (>10 mIU/mL).

§ A responder is defined as a person with anti-HBs >10 mIU/mL after 1 or more complete series of HepB vaccine.

¶ A nonresponder is defined as a person with anti-HBs <10 mIU/mL after 2 complete series of HepB vaccine.

** HCP who have anti-HBs <10mIU/mL, or who are unvaccinated or incompletely vaccinated, and sustain an exposure to a source patient who is HBsAg-positive or has unknown HBsAg status, should undergo baseline testing for HBV infection as soon as possible after exposure, and follow-up testing approximately 6 months later. Initial baseline tests consist of total anti-HBc; testing at approximately 6 months consists of HBsAg and total anti-HBc.

Source: This table from Prevention of Hepatitis B Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices. MMWR 2018;67(RR-1): 18 www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6701-H.pdf

Last reviewed: July 21, 2023

In general, no, but the type of testing (pre-exposure or post-exposure) depends on the healthcare worker’s profession and work setting. The risk for hepatitis B virus (HBV) infection for vaccinated healthcare personnel (HCP) can vary widely by setting and profession. The risk might be low enough in certain settings that assessment of hepatitis B surface antibody (anti-HBs) status and appropriate follow-up can be done at the time of exposure to potentially infectious blood or body fluids. This approach relies on HCP recognizing and reporting blood and body fluid exposures and might be applied on the basis of documented low risk, implementation, and cost considerations. Trainees, some occupations (such as those with frequent exposure to sharp instruments and blood), and HCP practicing in certain populations are at greater risk of exposure to blood or body fluid exposure from an HBsAg-positive patient. Vaccinated HCP in these settings/occupations would benefit from a pre-exposure approach.

Because CDC recommends, as of March 2023, that all adults receive a triple panel screening test for HBV once in their lifetime, it may be practical to conduct the routine triple panel test on any HCP who needs testing and has not had a triple panel screening test.

Last reviewed: July 21, 2023

Yes. The two available quadrivalent meningococcal conjugate vaccines, Menveo (MenACWY-CRM, GSK) and MenQuadfi (MenACWY-TT, Sanofi), they may be administered at the same time as PCV13 or at any interval before or after receipt of PCV13. If you are going to give him Menactra (MenACWY-D, Sanofi Pasteur), you need to wait at least 4 weeks after he completes the PCV13 series before giving him the Menactra to avoid the possibility of interference with the immune response to PCV13.

Last reviewed: April 5, 2024

Tetanus toxoid has never contained horse serum or protein. Equine tetanus antitoxin (horse derived) was the only product available for the prevention of tetanus prior to the development of tetanus toxoid in the 1940s. Equine antitoxin was also used for passive post-exposure prophylaxis of tetanus (e.g., after a tetanus-prone wound) until the development of human tetanus immune globulin in the late 1950s. Equine tetanus antitoxin has not been available in the U.S. for at least 40 years.

Last reviewed: March 31, 2022

Yes. Syncope may occur following any vaccination. It is prudent for all people to be observed for syncope for at least 15 minutes after any vaccination.

Last reviewed: September 10, 2023

No, but the PPSV23 will render the PCV13 dose less immunogenic. In this scenario, the best schedule is to give a MenACWY vaccination (any brand) simultaneously with either PCV15 or PCV20. If PCV20 is given, no additional pneumococcal vaccine doses are recommended. If PCV15 is given, then PPSV23 should be given at least eight weeks later. ACIP recommends giving PCV before PPSV23 in order to maximize the immune response from PCV. PPSV23 may blunt the immune response to PCV if PCV is given after PPSV23, although in children there is a smaller effect than in adults. Note that a 10-year-old child with persistent complement component deficiency should also be vaccinated against meningococcal B disease.

Last reviewed: April 5, 2024

A rare risk for myocarditis (inflammation of the heart muscle) and/or pericarditis (inflammation of the tissue surrounding the heart) has been observed following receipt of mRNA COVID-19 vaccines and Novavax COVID-19 Vaccine. Despite this observation, evaluation demonstrates that the benefits of vaccination clearly outweigh the risks in all age groups.

Among mRNA vaccine recipients, these rare cases of myocarditis or pericarditis have occurred most frequently in adolescent and young adult males within the first week after receiving the second dose of an mRNA COVID-19 vaccine primary series. Myocarditis is even more rare in children younger than age 12 years after COVID-19 vaccination. This risk appears related to age, biological sex, and the short (3- to 4-week) interval between primary series doses. Extending the interval to 8 weeks for some people for whom a vaccination series is recommended may reduce the rare risk of myocarditis following the second dose.

Most patients diagnosed with myocarditis after mRNA COVID-19 vaccination have been hospitalized for short periods, with most completely recovering from their acute symptoms. CDC is assessing long-term outcomes in people with myocarditis after mRNA COVID-19 vaccination.

People receiving COVID-19 vaccines, especially males age 12 through 39, should be counseled about the risk of myocarditis or pericarditis and advised to seek medical attention promptly if they develop chest pain, shortness of breath, or feelings of a fast, fluttering, or pounding heartbeat.

Cases of myocarditis and pericarditis were identified in clinical trials of Novavax COVID-19 Vaccine and have also been reported during post-authorization use outside the United States. These findings suggest that an increased risk for these conditions may be present after receiving Novavax COVID-19 vaccine.

Current recommendations are for a single dose of any FDA-licensed or FDA-authorized updated (2023–2024 Formula) COVID-19 vaccine for most people age 5 years and older, even if the individual is previously unvaccinated. Previously unvaccinated individuals who receive Novavax vaccine are recommended to receive two doses, given three to 8 weeks apart.

CDC’s complete interim clinical considerations for COVID-19 vaccination and myocarditis or pericarditis are available here: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#myocarditis-pericarditis.

CDC also has published additional clinical considerations for the evaluation and care of patients with myocarditis or pericarditis following mRNA vaccination: www.cdc.gov/vaccines/covid-19/clinical-considerations/myocarditis.html.

Last reviewed: March 19, 2024

ACIP recommends a single dose of tetanus immune globulin (TIG) for treatment of persons with tetanus. Although the optimal therapeutic dose has not been established, experts recommend 500 international units (IU), which appears to be as effective as higher doses ranging from 3,000 to 6,000 IU and causes less discomfort. Available preparations must be administered intramuscularly; TIG preparations available in the United States are not licensed or formulated for intrathecal or intravenous use. Infiltration of part of the dose locally around the wound is usually recommended if feasible, although the efficacy of this approach has not been proven. If TIG is not available, intravenous immune globulin (IGIV) can be used at a dose of 200 to 400 milligrams per kilogram (mg/kg). However, the Food and Drug Administration (FDA) has not approved IGIV for this use. In addition, anti-tetanus antibody content varies from lot to lot. See www.cdc.gov/tetanus/clinicians.html for more information on this issue.

Last reviewed: March 31, 2022

Certain vaccine syringes have small hubs where a volume of the vaccine that is withdrawn from the vial collects and is not available to be injected. Syringes without a hub are available; their use results in less vaccine wastage.

Last reviewed: September 10, 2023

ACIP recommends that healthcare personnel with written documentation of having received a properly spaced series of HepB in the past (such as in infancy or adolescence) but who now test negative for anti-HBs should receive a single “booster” or “challenge” dose of HepB and be retested 1–2 months later. Those who test positive following the “booster” dose are immune and require no further vaccination or testing. Those who test negative should complete a second 2- or 3-dose series of HepB on the usual schedule and be tested again 1–2 months after the last dose. The “booster” dose counts as the first dose in this series. Heplisav-B or PreHevbrio may be used to revaccinate new healthcare personnel (including the challenge dose) initially vaccinated with a vaccine from a different manufacturer in the distant past who have anti-HBs less than 10 mIU/mL upon hire or matriculation. For more information see www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6701-H.PDF, pages 21–22.

Last reviewed: July 21, 2023

Yes. These are all inactivated vaccines, which means you can give all other recommended vaccines at the same visit (using separate syringes) or at any later time with no waiting period following the vaccination. Menactra (MenACWY-D, Sanofi), a discontinued brand of meningococcal ACWY vaccine, was recommended not to be coadministered with pneumococcal vaccines due to evidence of interference with the immune response; however, Menactra is no longer available. All currently available meningococcal vaccines in the United States may be administered without regard to the timing of pneumococcal vaccination.

Last reviewed: April 5, 2024

Serious allergic reactions, such as anaphylaxis, in the minutes following vaccination are rare but are possible with any vaccine. Every vaccination site should have staff available who are trained and equipped to recognize and respond to signs of anaphylaxis in a vaccine recipient. See this CDC website for additional information about preparing for the management of anaphylaxis following COVID-19 vaccination: www.cdc.gov/vaccines/covid-19/clinical-considerations/managing-anaphylaxis.html?anaphylaxis-management.html.

Anaphylaxis following vaccination with mRNA COVID-19 vaccines is reported at a rate of approximately 2 to 5 cases per million doses administered.

An immediate severe allergic reaction to any component or previous dose of any mRNA COVID-19 vaccine is a contraindication to vaccination with both the Pfizer-BioNTech and Moderna vaccines (all formulations); however, such a reaction is generally a precaution to the use of the Novavax vaccine; see the CDC’s COVID-19 interim clinical considerations section on contraindications and precautions for details: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#contraindications.

CDC also provides specific COVID-19 vaccination guidance for people with a history of allergies or allergic reactions: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#history-allergies-reactions.

Last reviewed: March 19, 2024

Children age 7–10 years should receive Tdap if they are not fully vaccinated for prevention of pertussis. Otherwise they may receive Td or Tdap. If additional doses are necessary for full tetanus protection, they may be administered as Td or Tdap. Adolescents, and adults age 11 years and older should receive a single dose of Tdap, if they have not received a dose of Tdap after the 11th birthday, otherwise they may receive Td or Tdap. If additional doses are necessary for full tetanus protection, they may be administered as Td or Tdap.

Last reviewed: March 31, 2022

No. Only the number of doses indicated in the manufacturer’s package insert should be withdrawn from the vial. For a 5.0 mL vial of Fluzone Quadrivalent this is 10 doses. For Afluria Quadrivalent 5.0 mL multi-dose vial, the package insert states that the stopper can be punctured up to 20 times, allowing up to 20 doses of 0.25 mL dose for children age 6–35 months old. After the maximum number of doses has been withdrawn or number of punctures of the stopper has met the FDA-recommended limit, the vial should be discarded, even if there is vaccine remaining in the vial and the expiration date has not been reached.

Last reviewed: September 10, 2023

Anti-HBs testing for HCP who receive both hepatitis B immune globulin (HBIG) and hepatitis B vaccine can be conducted as soon as 6 months after receipt of the HBIG.

Last reviewed: July 21, 2023

The dose does not need to be repeated. However, this is a vaccine administration error. Clinicians should carefully select an influenza vaccine and vaccine dose that is licensed for the age group of the person being vaccinated. The error should be conveyed to the child’s parent or guardian and also reported to Vaccine Adverse Events Reporting System (VAERS) at www.vaers.hhs.gov. Actions should be taken to limit vaccine administration errors at the clinic where the error occurred. Immunize.org’s educational piece “Influenza Vaccine Products for the 2023-24 Influenza Season” (available at www.immunize.org/catg.d/p4072.pdf) provides helpful information on the wide variety of influenza vaccines in use this season.

Last reviewed: September 10, 2023

In accordance with general best practices for vaccination, all people should be observed for at least 15 minutes after vaccination for signs of an immediate allergic reaction.

If you vaccinate a person who has a precaution to COVID-19 vaccination, you should consider a 30-minute observation period following vaccination. See CDC’s detailed considerations for people with a history of allergies or allergic reactions: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#history-allergies-reactions.

Last reviewed: March 19, 2024

ACIP has not addressed this issue specifically. Puncture wounds, however, should be attended to as soon as possible. The decision to delay a booster dose of tetanus toxoid-containing vaccine following an injury should be based on the nature of the injury and likelihood that the injured person is susceptible to tetanus. The more likely the person is to be susceptible, the more quickly that tetanus prophylaxis should be administered. A person with a tetanus-prone wound (e.g., punctures, wounds contaminated with soil or fecal material) and who has no history of tetanus immunization must be vaccinated and given tetanus immune globulin (TIG) as soon as possible. A person with a documented series of at least three tetanus toxoid-containing products, with a booster dose within the previous 10 years ago is less likely to be susceptible to tetanus, and the need for a booster dose is not as urgent, particularly if the wound can be thoroughly cleaned. The more likely a person is to be completely susceptible to tetanus (i.e., unvaccinated or incompletely vaccinated), the sooner that TIG and Td/Tdap should be administered, even if it means a trip to the emergency department.

Last reviewed: March 31, 2022

No. The available data have been interpreted that any changes in antibody response to either vaccine’s components were clinically insignificant. If PCV20 and influenza vaccine are both indicated and recommended they should be administered at the same visit.

Last reviewed: April 5, 2024

No. HCP with written documentation of receipt of a complete, properly spaced HepB series AND a positive anti-HBs can be considered immune to HBV and require no further testing or vaccination. Testing unvaccinated or incompletely vaccinated HCP (including those without written documentation of vaccination) is not necessary and is potentially misleading because anti-HBs of 10 mIU/mL or higher as a correlate of vaccine-induced protection has only been determined for persons who have completed a HepB vaccination series. Persons who cannot provide written documentation of a complete HepB vaccination series should complete the series, then be tested for anti-HBs 1 to 2 months after the final dose.

Last reviewed: July 21, 2023

No. There are no data on the effectiveness of pneumococcal conjugate vaccine given by the intravenous route. The patient has renal disease, so it is important to ensure that the dose they receive is effective. CDC recommends repeating the dose using the correct route of administration (intramuscular).

Last reviewed: April 5, 2024

Pneumococcal vaccination recommendations are complex, especially as newer conjugate vaccines are licensed and added to recommended options. Assessing what is needed for an individual patient of any age requires their age, pneumococcal vaccination history, and knowledge of any relevant high-risk conditions. There are several resources available from CDC and Immunize.org that can help:

CDC Resources:

Immunize.org Resources:

Last reviewed: April 5, 2024

RIV4 is not licensed for people younger than 18 years of age, so there are no data regarding safety and efficacy in this age group. However, no serious side effects would be expected. The dose does not need to be repeated. Even if no adverse reaction occurs, vaccine administration errors like this should be reported to the Vaccine Adverse Events Reporting System (VAERS) at www.vaers.hhs.gov.

Last reviewed: September 10, 2023

Visit this CDC website for information for the public concerning allergic reactions and COVID-19 vaccines: www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/allergic-reaction.html.

For information about how to evaluate and manage people with a history of allergy who present for COVID-19 vaccination, see CDC’s additional considerations for people with a history of allergies or allergic reactions: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#history-allergies-reactions.

Last reviewed: March 19, 2024

One dose of tetanus toxoid-containing vaccine (Tdap or Td) provides little or no protection. That is why tetanus immune globulin (TIG) is also recommended in this situation. See the Tetanus Prophylaxis for Wound Management section of the current ACIP statement, available at www.cdc.gov/mmwr/volumes/67/rr/pdfs/rr6702a1-H.pdf, pages 27–28. As far as timing, the toxoid and TIG should be given as soon as possible.

Last reviewed: March 31, 2022

No. HCP who have documentation of receiving a complete HepB series and who tested positive for anti-HBs (defined as anti-HBs of 10 mIU/mL or higher) are considered to be immune to hepatitis B. Immunocompetent persons have long-term protection against HBV and do not need further testing or vaccine doses. Some immunodeficient persons (including those on hemodialysis) may need periodic booster doses of hepatitis B vaccine.

Last reviewed: July 21, 2023

PPSV23 may be administered by intramuscular (IM) or subcutaneous (Subcut) routes. Pneumococcal conjugate vaccines are administered IM. Immunize.org has produced a simple handout that summarizes the dose, route, site, and needle length for administration of all recommended vaccines to adults and children: www.immunize.org/catg.d/p3085.pdf.

Last reviewed: April 5, 2024

The following guidance is taken directly from the CDC: www.cdc.gov/vaccines/covid-19/clinical-considerations/interim-considerations-us.html#adverse-events.

For licensed COVID-19 vaccines (Moderna and Pfizer-BioNTech in people ages 12 years and older), healthcare providers are strongly encouraged to report to VAERS:

  • Any adverse event that occurs after the administration of a vaccine licensed in the United States, whether or not it is clear that a vaccine caused the adverse event
  • Vaccine administration errors, whether or not associated with an adverse event

For COVID-19 vaccines given under an EUA, vaccination providers are required to report to VAERS:

  • Vaccine administration errors, whether or not associated with an adverse event
  • Serious adverse events regardless of causality. Serious adverse events per FDA are defined as:
    • Death
    • A life-threatening adverse event
    • Inpatient hospitalization or prolongation of existing hospitalization
    • A persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions
    • A congenital anomaly/birth defect
    • An important medical event that based on appropriate medical judgement may jeopardize the individual and may require medical or surgical intervention to prevent one of the outcomes listed above
  • Cases of Multisystem Inflammatory Syndrome (MIS) in children and adults
  • Cases of myocarditis
  • Cases of pericarditis
  • Cases of COVID-19 that result in hospitalization or death

Reporting is also encouraged for any other clinically significant adverse event, even if it is uncertain whether the vaccine caused the event. Information on how to submit a report to VAERS is available at https://vaers.hhs.gov or by calling 1-800-822-7967.

Last reviewed: March 19, 2024

TIG is recommended for any wound other than a clean minor wound if the person’s vaccination history is either unknown, or the person has not had a full series of 3 doses of tetanus-containing vaccine. People with HIV infection or severe immunodeficiency who have contaminated wounds (including minor wounds) should also receive TIG, regardless of their history of tetanus immunizations. TIG should be given as soon as possible after the injury. The dose is 250 IU administered intramuscularly. See CDC’s web page for details: www.cdc.gov/tetanus/clinicians.html#wound-management.

Last reviewed: March 31, 2022

No. The series should not be restarted. Continue the series from where you left off.

Last reviewed: July 21, 2023

All pneumococcal vaccines should be refrigerated at temperatures between 2°C (36°F) and 8°C (46°F). Do not freeze these vaccines. Vaccine exposed to freezing temperature should not be administered. For details of vaccine storage and handling, see the CDC Vaccine Storage and Handling Toolkit: www.cdc.gov/vaccines/hcp/admin/storage/toolkit/index.html.

Last reviewed: April 5, 2024

Multiple national surveillance systems are used to monitor the safety of COVID-19 vaccines in different ways. CDC provides information about vaccine safety surveillance systems, with links to information about the safety of each licensed and recommended vaccine, including COVID-19 vaccines, here: www.cdc.gov/vaccinesafety/index.html.

Last reviewed: March 19, 2024

The incubation period of tetanus ranges from 3 to 21 days, averaging about 10 days. In general, the further the injury site is from the central nervous system, the longer the incubation period. In the opinion of the tetanus experts at the CDC, for a person who has been vaccinated but is not up to date, there is probably little benefit in giving TIG more than a week or so after the injury. For a person believed to be completely unvaccinated, it is suggested to increase this interval to 3 weeks (i.e., up to day 21 post injury). Td or Tdap should be given concurrently with TIG.

Last reviewed: March 31, 2022

If the error is discovered on the same clinic day you can administer the other “half” of the FluLaval Quadrivalent dose. If the error is discovered the next day or later, the dose should not be counted. The child should be recalled to the office as soon as possible and given a full age-appropriate repeat dose, either a 0.5 mL dose of FluLaval Quadrivalent, a 0.5 mL dose of Fluarix Quadrivalent, a 0.25 or 0.5 mL dose of Fluzone Quadrivalent, a 0.25 mL dose of Afluria Quadrivalent, or a 0.5 mL dose of Flucelvax Quadrivalent.

Last reviewed: September 10, 2023

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