Ask the Experts is one of our most popular destinations for healthcare professionals. Our experts provide clear, easy-to-understand answers to commonly asked questions about vaccines and their use.
Information regarding influenza surveillance is available year-round from CDC. For an overview and link to CDC’s influenza surveillance systems, visit www.cdc.gov/fluview/. CDC publishes updated information weekly. In addition, periodic updates about influenza are published in MMWR. CDC also publishes respiratory virus surveillance information that integrates influenza, COVID-19 and RSV at www.cdc.gov/respiratory-viruses/data/index.html.
State and local health departments should be consulted regarding local access to public health influenza vaccination programs and information about state or local influenza activity. Contact state or local health officials to report influenza outbreaks and for guidance in outbreak response.
There are many excellent websites that have information about vaccine safety, including the American Academy of Pediatrics, Vaccinate Your Family, Immunize.org, the National Academies of Science, Engineering, and Medicine, and the Vaccine Education Center of the Children’s Hospital of Philadelphia.
Medicare Part B (which primarily covers medical outpatient care costs) covers four recommended vaccines for all Medicare beneficiaries: COVID-19, hepatitis B (whether or not a risk factor is reported), influenza, and recommended pneumococcal conjugate and pneumococcal polysaccharide vaccines. Medicare Part B does not cover other adult vaccinations (e.g., Tdap) unless they are directly related to the treatment of an injury or direct exposure to a disease, such as anti-rabies treatment or tetanus prevention due to an injury. In the absence of injury or direct exposure, all other vaccines, including zoster, are covered by Medicare Part D.
Medicare Part D plans (outpatient prescription drug insurance) cover the Advisory Committee on Immunization Practices (ACIP) recommended vaccines that Part B does not cover (for example, RSV and zoster). Since early 2023, the Inflation Reduction Act of 2022 has required Medicare Part D plans to cover ACIP-recommended adult vaccinations without a deductible or copay when given by an in-network provider. Medicare Part D coverage also includes ACIP-recommended vaccines recommended for an individual as a result of occupational or travel-related risks. A summary of adult vaccine insurance coverage can be found at https://www.izsummitpartners.org/wp-content/uploads/NAIIS_Vaccine-insurance-coverage-2024-2025.pdf.
No. Doses of rabies vaccine given in the gluteus should not be counted as valid and should be repeated. If repeating the invalid dose results in an interval between doses more than 3 days longer than the recommended interval, then you should perform a rabies serology 7–14 days after administration of the final dose in the series to ensure an adequate immune response to the series. For more information about rabies serology, see www.cdc.gov/rabies/php/labs-specimens/testing.html.
CDC recommends applying the standard 28-day interval between yellow fever vaccine and other live virus vaccines when they are not administered simultaneously. In the past, a 30-day minimum interval was recommended specifically for yellow fever vaccine, but CDC no longer recommends a different interval for yellow fever vaccine. For details, see CDC’s web section on timing and spacing of immunobiologics: www.cdc.gov/vaccines/hcp/imz-best-practices/timing-spacing-immunobiologics.html#cdc_report_pub_study_section_5-non-simultaneous-administration
Immunize.org has developed several resources that can help patients identify what they may need. These include:
Translations of these handouts are also available in several languages. To access all of Immunize.org’s clinical resources available in languages other than English, visit www.immunize.org/translations/. All of these clinical resources can be found in the subsection of clinical resources that address adult immunization: www.immunize.org/clinical/topic/adult-vaccination/.
As a general rule, infants or children who are more than 1 month or 1 dose behind schedule should be on an accelerated schedule, which means the intervals between doses should be reduced to the minimum allowable. Catch-up schedules for children ages 4 months through 18 years are included in Table 2 of each year’s recommended immunization schedule for children and adolescents published by CDC. To review Table 2, go to www.cdc.gov/vaccines/hcp/imz-schedules/child-adolescent-age.html and open the current schedule for children and adolescents.
The recommended immunization schedule published by the American Academy of Pediatrics (AAP) also includes a catch-up schedule as Table 2 of its schedule, available here: https://downloads.aap.org/AAP/PDF/AAP-Immunization-Schedule.pdf.
Generally speaking, CDC recommends avoiding the top shelf and the areas near vents due to temperature fluctuations. However, most purpose-built or pharmaceutical-grade units use a fan to circulate air within the storage area and create more uniform temperatures than household units. During a power outage, the top shelf is an area of caution for all units as the temperatures increase most quickly there. In this instance, it would be best to check with the manufacturer or owner’s manual to see if the top shelf is appropriate for storage in your unit. Units that meet the NSF/ANSI 456 voluntary certification standard are designed to deter the user from placing vaccines in areas where proper storage temperatures cannot be maintained, so any shelf available storage in a certified unit would be usable.
Vaccine efficacy (VE) during clinical trials in multiple countries ranged from 76% to 82%. VE varied by serotype and was highest for DENV-4 (89% point estimate) and lowest for DENV-1 and DENV-2 (67% point estimate). Among study participants ages 9 through 16 years who developed protective antibodies, the vaccine reduced their risk of hospitalization with dengue by 79% and reduced their risk of severe dengue by 84% over the 5-year follow-up period after vaccination. Studies are ongoing to determine how long protection from hospitalization or severe disease may last, but current evidence show protection lasting at least 6 years after the last dose of vaccine.
One pneumococcal polysaccharide vaccine (PPSV23, Pneumovax 23, Merck) and three pneumococcal conjugate vaccines (PCV15 [Vaxneuvance, Merck], PCV20 [Prevnar 20, Pfizer], and PCV21 [Capvaxive, Merck]) are FDA-licensed and recommended by CDC for use in the United States. PCV13 (Prevnar 13, Pfizer) is FDA-licensed and may still be available in some clinics. It is no longer routinely recommended; however, CDC guidance allows for its use as previously recommended in situations where PCV15, PCV20, or PCV21 is indicated but unavailable and the alternative is that the patient would not be vaccinated.
PPSV23 is licensed for age 2 years and older. It was first licensed in 1983. It is an option for use in series with PCV15 for children and adults ages 2 through 64 years with specified risk factors for pneumococcal disease depending on their prior pneumococcal vaccination history. A PCV15 + PPSV23 series also is recommended as an option for pneumococcal disease prevention in adults 50 years and older. Following the 2022 changes to the pneumococcal vaccination schedule for adults, PPSV23 is no longer recommended alone, however PPSV23 is recommended for adults following PCV15 vaccination. It is not recommended for people who have previously received a PCV20 or PCV21 vaccination.
PCV15 is licensed for people age 6 weeks and older. CDC recommends the use of PCV15 as an option for the routine vaccination of children younger than age 5 years and certain children 6 through 18 years who have conditions that put them at high risk of invasive pneumococcal disease. CDC recommends PCV15 in series with PPSV23 as an option for pneumococcal disease prevention in adults age 19 through 49 years who are at increased risk for invasive pneumococcal disease due to behavioral or medical risk factors and for adults age 50 or older. When used in adults, it is always recommended to be used as part of a vaccination series with PPSV23 typically given 1 year later (a minimum interval of 8 weeks may be considered for people with immunocompromising medical conditions, cochlear implant or cerebrospinal fluid leak).
PCV20 is licensed for people age 6 weeks and older. CDC recommends the use of PCV20 as an option for the routine vaccination of children younger than 5 years of age and certain children 6 through 18 years who have conditions that put them at high risk of invasive pneumococcal disease. CDC recommends it as an option for pneumococcal disease prevention in adults age 19 through 49 years who are at increased risk for invasive pneumococcal disease due to behavioral or medical risk factors and for adults age 50 or older. If PCV20 is given, no further pneumococcal vaccination is recommended.
PCV21 was first licensed and recommended for adults in June 2024. CDC recommends the use of PCV21 as a product option for any adult age 19 or older when a PCV vaccine is recommended. It is specifically designed for adults: it does not contain 10 serotypes contained in PCV20; instead, it contains 11 additional serotypes that cause disease in adults. As with PCV20, after it is administered, no further pneumococcal vaccine doses are recommended.
For details of recommendations for these vaccines, see Recommendations for Pneumococcal Vaccines Use in Children and Teens, www.immunize.org/wp-content/uploads/catg.d/p2016.pdf, or Standing Orders for Administering Pneumococcal Vaccines to Adults: www.immunize.org/wp-content/uploads/catg.d/p3075.pdf.
The most current comprehensive recommendations from the Advisory Committee on Immunization Practices (ACIP) for meningococcal vaccines is available on the MMWR website at www.cdc.gov/mmwr/volumes/69/rr/pdfs/rr6909a1-H.pdf. This document replaces all previously published reports and policy notes.
ACIP recommendations for the use of MenABCWY (Penbraya) were published in the MMWR in April 2024 and are at www.cdc.gov/mmwr/volumes/73/wr/pdfs/mm7315a4-H.pdf.
The most recent comprehensive Advisory Committee on Immunization Practices (ACIP) recommendations for Hib vaccination were published in 2014 and are available on the CDC website at www.cdc.gov/acip-recs/hcp/vaccine-specific/hib.html. An ACIP update, adding Vaxelis (DTaP-IPV-Hib-HepB, MSP Company) as a preferred Hib-containing option for vaccination of American Indian/Alaska Native children was published in September 2024 and is also available at the link above. Guidance for Hib vaccination is also provided in the annual childhood immunization schedule, available at www.cdc.gov/vaccines/hcp/imz-schedules/child-adolescent-age.html.
If a provider suspects an invalid vaccination, including those from persons vaccinated outside the U.S., one of two approaches can be taken. Repeating the vaccinations is an acceptable option. Doing so is generally safe and avoids the need to obtain and interpret serologic tests. If avoiding unnecessary injections is desired, judicious use of serologic testing might be helpful in determining which immunizations are needed. This may be particularly helpful in determining tetanus and diphtheria antitoxin levels for children whose records indicate 3 or more doses of DTP or DTaP. This issue is discussed in detail in the CDC’s “General Best Practices for Immunization” chapter titled Special Situations, and summarized in Table 9-1, available at www.cdc.gov/vaccines/hcp/imz-best-practices/special-situations.html.
There are no specific data on transmission of bloodborne viruses through oral-genital sex. Saliva has not been associated with HBV transmission unless biting has taken place. HBV is not spread by kissing, hugging, sneezing, coughing, food or water, sharing eating utensils or drinking glasses, or casual contact.
No. ACIP does not recommend routinely checking a patient’s temperature or other vital signs before vaccination. Requiring these extra steps can be a barrier to immunization.
Occupational infection with HPV is possible. Some HPV-associated conditions (including anogenital and oral warts, anogenital intraepithelial neoplasia, and recurrent respiratory papillomatosis) are treated with laser or electrosurgical procedures that could produce airborne particles. These procedures should be performed in an appropriately ventilated room using standard precautions and local exhaust ventilation. Workers in HPV research laboratories who handle wild-type viruses or “quasi virions” might be at risk of acquiring HPV from occupational exposures. In the laboratory setting, proper infection control should be instituted, including, at minimum, biosafety level 2. Whether HPV vaccination would be of benefit in these settings is unclear because no data exist on transmission risk or vaccine efficacy in this situation.
CDC recommends individual decision-making (also known as shared clinical decision-making) for COVID-19 vaccination of all people age 6 months and older. Among people age 6 months through 64 years, ACIP emphasizes that the risk-benefit of vaccination is most favorable for individuals who are at an increased risk for severe COVID-19 disease and lowest for individuals who are not at an increased risk. Details of the vaccination schedule are available here: www.cdc.gov/covid/hcp/vaccine-considerations/routine-guidance.html.
Of note, among previously unvaccinated people who are not moderately or severely immunocompromised, an initial vaccination series is recommended only for young children age 6 through 23 months. All others younger than age 65 years are recommended to receive a single dose of an age-appropriate 2025–2026 formula COVID-19 vaccine. People age 65 years and older are recommended to receive a second 2025–2026 formula COVID-19 vaccine dose 6 months later (minimum interval 2 months if using Comirnaty, Spikevax, or Nuvaxovid; minimum interval 3 months if using mNexspike).
Major U.S. professional medical societies have issued their own recommendations for the 2025–26 COVID-19 season that differ from CDC, primarily in their stronger, routine recommendations for vaccination of people at risk of severe COVID-19 illness:
Immunity to one of the serotypes of polio does not produce significant immunity to the other serotypes. A history of having recovered from polio disease should not be considered evidence of immunity to polio. You should complete a primary series of IPV if he is known or suspected to have been unvaccinated or incompletely vaccinated against polio. If he received a primary series in childhood, a single adult booster dose may be given before travel to an area where polio vaccination is recommended.
With some exceptions, there aren’t VISs for combination vaccines. Instead, providers should provide a separate VIS for each vaccine component in the combination (e.g., DTaP-IPV-HepB or DTaP-IPV/Hib). There is a combined VIS (the multi-vaccine VIS) that can substitute for any or all of the routine vaccines given from birth–6 months (DTaP, IPV, Hib, PCV and HepB vaccines). VISs in English and many other languages are available at www.immunize.org/vis/.
People who are moderately or severely immunocompromised are at increased risk for severe COVID-19 illness. ACIP and CDC recommend individual decision-making (also known as shared clinical decision-making) after a discussion with a healthcare professional (nurse, doctor, or pharmacist) for people age 6 months and older who are moderately or severely immunocompromised. They are recommended to receive at least 2 doses during the season. The CDC vaccination schedule for people with moderate or severe immunocompromise is available here: www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html.
The Infectious Diseases Society of America (IDSA) strongly recommends administration of age-appropriate 2025–2026 COVID-19 vaccinations to all adults and children with compromised immunity. They also recommend that household members and close contacts of immunocompromised people should be up to date with COVID-19 vaccination. See IDSA recommendations for full details: www.idsociety.org/Seasonal-RTI-Vaccinations-in-Immunocompromised-Patients/.
In June 2023, ACIP recommended that all adults (18 years and older) in the United States who are known or suspected to be unvaccinated or incompletely vaccinated against polio should complete a primary 3-dose vaccination series with IPV: 2 doses of IPV administered at an interval of 4–8 weeks; and a third dose should be administered 6–12 months after the second. Previously, ACIP did not recommend IPV vaccination of unvaccinated or incompletely vaccinated adults who lacked a specific increased risk for exposure to polio (e.g., due to travel). Most U.S. adults may be presumed to be vaccinated against polio unless there is a specific reason to believe otherwise (e.g., an adult whose parents were known to have refused vaccinations). Rates of polio vaccination among children in the United States have been extremely high for decades.
In past seasons, CDC recommended that all doses of COVID-19 vaccine given to children age 6 months through 4 years be from the same manufacturer. However, in the 2025–26 season, only Moderna’s Spikevax mRNA vaccine is licensed and recommended for use in children younger than age 5 years. All children in this age group who are vaccinated against COVID-19 should receive Spikevax, regardless of the brand they received in previous seasons. If the child is age 6 months through 23 months and received an incomplete (1- or 2-dose) initial COVID-19 vaccination series with Pfizer-BioNTech, a 3-dose initial series should be completed with Spikevax. It is not necessary to repeat the initial series.
In previously unvaccinated people age 5 years or older with moderate or severe immunocompromise, the same manufacturer is recommended for all initial COVID-19 vaccine series doses (either 2 doses of Nuvaxovid [if age 12 years or older] or 3 doses of an mRNA product). After completion of the initial series, any age-appropriate COVID-19 vaccine may be used in this age group.
CDC sets out conditions when it is acceptable to use an age-appropriate COVID-19 vaccine from a different manufacturer in any situation where the same manufacturer is recommended:
Individuals with moderate to severe immunocompromise who have completed an initial COVID-19 series should receive two dose of 2025–2026 Formula COVID-19 vaccine this season with the second dose given 6 months later (minimum interval 2 months for Comirnaty, Spikevax, and Nuvaxovid; minimum interval 3 months for mNexspike).
In previous seasons, CDC recommended that additional doses of COVID-19 vaccine may be administered (with a minimum two-month interval) based on the clinical judgment of the individual’s healthcare provider and the recipient’s personal preference and circumstances. For the 2025–26 season, CDC has removed this general statement from its interim clinical considerations document (www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html). The CDC clinical considerations document now states, “On a case-by-case basis, providers caring for these patients may administer Moderna, Novavax, and Pfizer-BioNTech COVID-19 vaccines outside of the FDA and CDC dosing intervals when, based on their clinical judgment, the benefits of vaccination are deemed to outweigh the potential and unknown risks for the recipient who is immunocompromised.”
In June 2023, ACIP affirmed its longstanding recommendation that adults who received a primary series of trivalent OPV (tOPV) or IPV in any combination and who are at increased risk of poliovirus exposure may receive another dose of IPV. Available data do not indicate the need for more than a single lifetime booster dose with IPV for adults.
The following are examples of vaccinated adults at increased risk of exposure who may receive a single lifetime booster dose of IPV:
Recent Tdap vaccination does not affect PCR testing. PCR tests are used to detect DNA sequences of the Bordetella pertussis bacterium. PCR tests are very sensitive and could give a false positive result for other reasons. For more information on best practices when performing PCR testing for pertussis see www.cdc.gov/pertussis/php/pcr-bestpractices.
Recombinant zoster vaccine (RZV, Shingrix, GSK) was licensed by the Food and Drug Administration (FDA) in October 2017. It is a subunit vaccine that contains recombinant varicella zoster virus (VZV) glycoprotein E in combination with a novel adjuvant (AS01B). Shingrix does not contain live VZV. It is FDA-approved and recommended by the Advisory Committee on Immunization Practices (ACIP) for all people 50 years and older and for adults age 19 years or older who are or will be immunodeficient or immunosuppressed because of disease or therapy. It has not been evaluated and is not approved for the prevention of primary varicella infection (i.e., chickenpox). Shingrix is administered as a 2-dose series by the intramuscular route. The second dose should be given 2 to 6 months after the first dose, with a minimum interval of 1 month (4 weeks) between doses.
Zoster vaccine live (ZVL, Zostavax, Merck) is a live attenuated vaccine that was licensed by the FDA in 2006 for adults age 50 and older and recommended by ACIP for people age 60 and older. Zostavax has been unavailable for use in the United States since November 18, 2020.
Yes. TBE is caused by a flavivirus transmitted by ticks in certain regions of Asia and Europe. Most infections are asymptomatic, but it can cause meningitis and encephalitis. In August 2021, the FDA approved a TBE vaccine, Ticovac (by Pfizer), for people age 1 year or older. The dose for people age 16 years and older is 0.5mL, and for children and adolescents up to age 15 years is 0.25mL. The primary vaccination schedule includes 3 doses, and a booster dose can be given if ongoing exposure or re-exposure to TBE virus is expected. TBE vaccines are also available in many countries overseas where TBE virus is present. For more information from CDC about the TBE vaccine, visit www.cdc.gov/tick-borne-encephalitis/hcp/vaccine/index.html.
MenACWY is recommended for these groups:
Routine vaccination of all children and teens, age 11 through 18 years: a single dose at age 11 or 12 years with a booster dose at age 16 years
Routine vaccination of people age 2 months or older at increased risk for meningococcal disease (the primary dosing schedule and booster dose interval varies by age and indication):
Nonsexual HPV transmission is theoretically possible but has not been definitively demonstrated. This is mainly because HPV can’t be cultured, and DNA detection from the environment is difficult and likely prone to false negative results.
The two rotavirus vaccine products differ in composition and schedule of administration. RotaTeq was approved by the Food and Drug Administration (FDA) in 2006. It contains five reassortant rotaviruses developed from human and bovine parent rotavirus strains; 3 doses are given in the series. Rotarix was approved by the FDA in 2008 and contains an attenuated human rotavirus strain; 2 doses are given in the series.
Yearly influenza vaccination continues to be recommended for everyone age 6 months and older. Changes relevant to clinical practice in the CDC’s published ACIP recommendations for influenza vaccination in the 2025–26 season are summarized below:
The current ACIP recommendations for influenza vaccination are available here: www.cdc.gov/acip-recs/hcp/vaccine-specific/flu.html.
Syncope, also called fainting, is a temporary loss of consciousness as a result of decreased blood flow to the brain. The most common form of fainting is called “vasovagal” fainting. This type of fainting can be triggered by an event associated with pain or anxiety. Some people may experience jerking movements after fainting which are not seizures. Published literature reveals that about 3% of men and 3.5% of women report at least one episode of fainting during their lifetime.
There is usually very close agreement between vaccine package inserts and ACIP statements. The Food and Drug Administration (FDA) must approve the package insert and requires documentation for all data and recommendations made in the insert. Occasionally, ACIP may use different data to formulate its recommendations, or try to add flexibility to its recommendations, which results in wording different that in the package insert. ACIP has sometimes made recommendations based on expert opinion and public health considerations. Traditionally, published recommendations of ACIP have been considered equally as authoritative as those on the package insert.
The accelerated schedule should be used when the child is more than a month behind schedule, until you get them caught up. An accelerated schedule is acceptable as long as minimum ages and minimum intervals are observed for each dose. Once you have the child back on schedule, use the recommended ages and intervals on the childhood schedule. In this case you can give the child the first set of recommended vaccines at age 3 months and then bring him back at age 4 months and give the second set of vaccinations. At this point the child will be caught up and can return to the usual schedule. Be sure to educate the parents and talk to them about the importance of bringing the child back on time.
No. If you turn off the freezer portion of a household-style combination refrigerator/freezer, the refrigerated compartment will not maintain the proper temperature.
CDC recommends that all travelers to countries affected by wild (WPV) or circulating vaccine-derived poliovirus (cVDPV) be vaccinated fully against polio. Adults who were fully vaccinated during childhood may receive an additional (single) lifetime booster dose of polio vaccine.
WHO recommends that countries affected by wild poliovirus or cVDPV outbreaks require residents and long-term (4 weeks or more) visitors show proof of polio vaccination before leaving the country. These recommendations are regularly reviewed and updated. Visit CDC’s Travelers’ Health site for current details about country-specific requirements (wwwnc.cdc.gov/travel/).
MenB is routinely recommended for these groups:
For adolescents and young adults not otherwise at increased risk for meningococcal B disease, ACIP recommends that a MenB series may be administered to people 16 through 23 years of age (preferred age 16 through 18 years) on the basis of shared clinical decision-making. The shared clinical decision-making recommendation allows the clinician and patient to decide together based upon the risks and benefits of vaccination for the individual patient.
Ideally, you can arrange to have the cast cut to administer vaccines in the anterolateral thighs. If that option is not available, the gluteal region can be used if not covered by the cast. There are no other sites recommended for vaccination; however, the inactivated polio vaccine could be given subcutaneously in either arm, if the child is large enough. Rotavirus vaccine is given orally and should be administered. If vaccines cannot be given for the 10 weeks, please advise the family to keep people with any illness away from the child until she has been vaccinated. For more information see the vaccine administration section of CDC’s “General Best Practices for Immunization”, available at www.cdc.gov/vaccines/hcp/imz-best-practices/vaccine-administration.html.
Three monovalent Hib vaccines are available in the United States: PedvaxHIB (PRP-OMP, Merck), ActHIB (PRP-T, Sanofi) and Hiberix (PRP-T, GSK). These vaccines are composed of Hib purified polyribosylribitol phosphate (PRP) capsular polysaccharide chemically bound (conjugated) to a protein to enhance the quality of the immune response to PRP. All three vaccines are approved for infants in a 3- or 4-dose series (depending on brand).
Two combination vaccines containing Hib are currently available in the United States: Pentacel (DTaP-IPV/Hib, Sanofi) and Vaxelis (DTaP-IPV-Hib-HepB, MSP Company). Pentacel is licensed for use in children younger than age 5 years and contains Hib conjugate, DTaP, and inactivated polio vaccines; it is approved as a 4-dose series for infants at age 2, 4, 6, and 15 through 18 months, but it is not approved for use as the DTaP/IPV booster dose recommended at age 4 to 6 years. Vaxelis (DTaP-IPV-Hib-HepB) is licensed for use in children younger than age 5 years and is FDA-approved and recommended by CDC as a 3-dose primary series of Hib for infants at age 2, 4, and 6 months. Vaxelis is not approved for use as a Hib booster (4th) dose. Vaxelis contains the same PRP-OMP Hib antigen as PedvaxHIB, but in a reduced amount; like PedvaxHIB, it is an ACIP-preferred option for administration to American Indian and Alaska Native infants (who are at increased risk of early-onset invasive Hib disease) because it induces protective antibody levels after the first dose.
In May 2022, CDC published updated ACIP recommendations for rabies PrEP based on risk categories. All people in categories 1-4 should receive a 2-dose primary PrEP rabies vaccine series. People in categories 1-3 require additional long-term follow-up with periodic antibody titer checks and/or booster doses, depending on the category. See the table on pages 622-623 of the MMWR publication for details: www.cdc.gov/mmwr/volumes/71/wr/pdfs/mm7118a2-H.pdf.
In brief, the risk categories are as follows:
A “moderate or severe acute illness” is a precaution for administering any vaccine. A mild acute illness (e.g., diarrhea or mild upper-respiratory tract infection) with or without fever is not a precaution, and vaccines may be given. The concern in vaccinating someone with moderate or severe illness is that a fever following the vaccine could complicate management of the concurrent illness – it could be difficult to determine if the fever was from the vaccine or due to the concurrent illness. In deciding whether to vaccinate a patient with moderate or severe illness, the clinician needs to determine if deferring vaccination will increase the patient’s risk of vaccine-preventable diseases, as is the case if the patient is unlikely to return for vaccination or to seek vaccination elsewhere.
No, Dengvaxia does not protect the recipient against yellow fever.
The most recent comprehensive ACIP recommendations for the use of MMR vaccine were published in 2013 and are available at www.cdc.gov/mmwr/pdf/rr/rr6204.pdf. CDC published the ACIP recommendations for the use of Priorix (GSK) brand of MMR vaccine on November 18, 2022, and they are available here: www.cdc.gov/mmwr/volumes/71/wr/pdfs/mm7146a1-H.pdf.
There is no difference in recommendations between Priorix and MMRII (Merck) brands of MMR vaccine. Priorix may be used in any situation where MMR vaccination is recommended. Despite minor differences in manufacturing (MMRII contains gelatin; Priorix does not) and approved route of administration (MMRII is approved for subcutaneous or intramuscular injection; Priorix is approved for subcutaneous injection only), the two vaccines may be considered functionally identical and interchangeable.
MMR vaccine is recommended routinely for all children at age 12 through 15 months, with a second dose at age 4 through 6 years. The second dose of MMR can be given as early as 4 weeks (28 days) after the first dose and be counted as a valid dose if both doses were given after the child’s first birthday. The second dose is not a booster, but rather is intended to produce immunity in the small number of people who fail to respond to the first dose.
Adults with no evidence of immunity should get 1 dose of MMR vaccine (evidence of immunity is defined as documented receipt of 1 dose of live measles virus-containing vaccine [or 2 doses, if high risk], laboratory evidence of immunity or laboratory confirmation of disease, or birth before 1957), unless the adult is in a high-risk group.
Susceptible high-risk people need 2 doses of MMR vaccine, given 4 weeks apart. High-risk people include school-age children, healthcare personnel, international travelers, students attending post-high school educational institutions, people with HIV infection (vaccinate only if CD4 percentages are at least 15% and CD4 count is at least 200 cells/mm3), and close contacts of immunocompromised people.
Live measles vaccine became available in the United States in 1963. An ineffective, inactivated measles vaccine was also available in the United States in 1963–1967 and administered to fewer than 1 million people during that time. Combined MMR vaccine (MMRII, Merck) was licensed in 1971; Priorix (GSK) MMR vaccine was licensed and recommended in 2022. For people who previously received a dose of measles vaccine in 1963–1967 and are unsure which type of vaccine it was, or are sure it was inactivated measles vaccine, that dose should be considered invalid and the patient revaccinated as age- and risk-appropriate with MMR vaccine. If the person can confirm they received a live vaccine during that era, the dose is considered valid and does not need to be repeated.
At the discretion of the state public health department, anyone exposed to measles in an outbreak setting may receive an additional dose of MMR vaccine, even if they meet the routine criteria for acceptable evidence of immunity for their age or risk status, such as being unvaccinated but born before 1957, or being a low-risk adult with a history of only one MMR vaccine.
Janssen (Johnson & Johnson) COVID-19 vaccine is no longer produced. The last remaining doses expired May 7, 2023. The history of Janssen vaccine use is relevant only to evaluation of an adult with moderate or severe immunocompromise because such individuals are recommended to receive an initial series of COVID-19 vaccine. History of a single dose of Janssen COVID-19 vaccine constitutes a complete initial series. A person with this history should follow the vaccination schedule recommended for an immunocompromised person who has already completed an initial vaccination series.
All commercial insurance plans compliant with the Affordable Care Act (ACA) should cover vaccines listed on the CDC’s recommended schedules for vaccines for children and adults without any cost-sharing (e.g., no deductible or copay) when given by in-network providers.
The Inflation Reduction Act (IRA) of 2022, which was fully enacted during 2023, substantially reduced cost-related barriers to vaccination for adults. The law eliminated cost-sharing for ACIP-recommended vaccination of all adults covered by traditional Medicaid and Medicaid expansion plans, as well as adults with Medicare Part D. More information about the ACA and IRA legislation impact on vaccine payment is available in this pdf report published by Avalere on October 2, 2023: https://avalere.com/wp-content/uploads/2023/10/Guide-to-Vaccine-Coverage-Policies.pdf.
The National Adult and Influenza Immunization Summit (NAIIS) has created a web section with resources on billing and coding for adult vaccinations at www.izsummitpartners.org/naiis-workgroups/access-provider-workgroup/coding-and-billing.
There are three RSV vaccines licensed and recommended in the United States. Each is listed below, along with their FDA-licensed indications:
All three may be used as recommended by CDC and ACIP as a single dose for all adults age 75 years or older and for adults age 50 through 74 years with high-risk conditions for severe RSV disease. Only Abrysvo is licensed for use during pregnancy (during 32 through 36 weeks and 6 days’ gestation) for the prevention of RSV disease in infants.
Arexvy and Abrysvo are recombinant protein vaccines that contain the prefusion form of the F protein found on the surface of the RSV virus. The mResvia mRNA vaccine contains mRNA that encodes the prefusion form of the RSV F glycoprotein. The mRNA vaccine temporarily enables some of the vaccine recipient’s own cells to produce the prefusion form of the RSV F protein, causing the immune system to respond by generating antibodies to it. Because none of these vaccines contain live virus, they cannot cause RSV illness.
The GSK vaccine, Arexvy, includes an AS01adjuvant, a chemical designed to enhance the immune response to vaccination. AS01 is the same adjuvant used in GSK’s recombinant zoster vaccine (Shingrix), but Arexvy contains half the amount of adjuvant as a dose of Shingrix. Abrysvo and mResvia vaccines do not contain an adjuvant.
The incidence of hepatitis A in the US increased more than 10-fold from 2015 to 2019, with over 18,800 cases reported to CDC in 2019. The number of reported cases declined by 47% to 9,952 in 2020. This number is an underestimate of the actual number of infections: CDC estimates that about 19,900 cases actually occurred in 2020.
Between 2012 and 2015 the number of reported hepatitis A infections ranged from approximately 1200 to 1800 cases every year. Beginning in 2016, large foodborne outbreaks led to an increase in the number of cases and sustained, large person-to-person outbreaks began, primarily driven by infections among unvaccinated people who use drugs and people experiencing homelessness and their contacts. Since then, persistent person-to-person outbreaks have led to substantial increases in hepatitis A infection, with 37 states reporting almost 45,000 cases over the 7 years between the beginning of the outbreaks in 2016 and June 2023. The rate of new cases has declined substantially since the peak in 2019. More information regarding ongoing multistate outbreaks can be found here: www.cdc.gov/hepatitis/outbreaks/.
A polysaccharide vaccine is a type of vaccine that is composed of long chains of sugar molecules, called polysaccharides, that resemble the surface of certain serotypes of pneumococcal bacteria in order to help the immune system mount a response.
A conjugate vaccine is a type of vaccine that joins a protein to an antigen (in the case of pneumococcal vaccines, the protein is connected to unique polysaccharides from the surface of each of the pneumococcal serotypes). The protein helps improve the quality of the immune system response to the vaccine compared to the response to an unconjugated polysaccharide.
Pediarix contains the vaccine components DTaP, IPV, and HepB. The primary series is 3 doses (0.5 mL) given intramuscularly at 2, 4, and 6 months of age. Pediarix is licensed by the Food and Drug Administration (FDA) for only the first 3 doses of the DTaP series. It should not be given to infants younger than 6 weeks of age or to children 7 years or older.
Generally speaking, no. A person with laboratory evidence of resolved hepatitis B infection is considered immune. Vaccination of such individuals is not harmful but is not necessary.
All children, beginning at age 12 months, as well as adults without evidence of immunity (see this question) should be vaccinated with 2 doses of varicella vaccine. Special consideration should be given to vaccinating adults who (1) have close contact with people at high risk for severe disease (e.g., healthcare workers and family contacts of immunocompromised people), or (2) are at high risk for exposure or transmission (e.g., teachers of young children; child care employees; residents and staff members of institutional settings, including correctional institutions; college students; military personnel; adolescents and adults living in households with children; non-pregnant women of childbearing age; and international travelers).
Shingrix was studied in immunocompetent adults in 2 pre-licensure clinical trials. Efficacy against shingles was 97% for people 50–59 years of age, 97% for people 60–69 years of age, and 91% for people 70 years and older. Among people 70 years and older vaccine efficacy was 85% four years after vaccination.
Vaccine effectiveness (VE) has been evaluated for a limited number of specific immunocompromising conditions. VE estimates vary depending upon the underlying cause of immunocompromise. Studies have estimated VE of 68.2% for autologous hematopoietic cell transplant recipients, and 87.2% and 90.5% for patients with hematologic malignancies and potential immune-mediated diseases, respectively.
CDC considers evidence of immunity to varicella to be:
*Note: Although there is only a very small chance of susceptibility, due to the potential for severe consequences from varicella infection, year of birth is not accepted as evidence of varicella immunity for healthcare personnel, immunosuppressed people, and pregnant people.
The terminology change from “Category B” to “shared clinical decision-making” was done to describe more clearly the intent of the recommendation that the patient should be informed of the option to be vaccinated against meningococcal serogroup B disease and that the decision to vaccinate against MenB should be made by the provider and patient together. ACA requires coverage of vaccines as indicated on the recommended immunization schedule, including vaccines with shared clinical decision-making recommendations. The Vaccines for Children (VFC) program also covers vaccines recommended for shared clinical decision-making.
Tick-borne encephalitis (TBE) is a disease caused by a flavivirus transmitted by tick bite in certain areas of Europe and Asia. It may also be transmitted through the consumption of unpasteurized milk or cheese from infected cows, goats, or sheep. CDC provides details of TBE-endemic areas, but notes that the risk of TBE in endemic areas is variable within risk areas and from year-to-year. Additional geographic information is available from CDC: www.cdc.gov/tick-borne-encephalitis/data-maps/.
Travelers moving or traveling to a TBE-endemic area and likely to have extensive exposure to ticks based on their planned outdoor activities and itinerary should be vaccinated for TBE. TBE vaccination may be considered for other travelers to TBE-endemic areas based on their likely exposure to ticks during their activities, their risk of a poor health outcome, and their personal perception and tolerance of risk.
The polysaccharide vaccine includes the different polysaccharides (chains of complex sugars) from different serotypes as the antigen. The conjugate vaccines have the polysaccharides for different serotypes attached (or conjugated) to a carrier protein. The immune response to the PPSV23 vaccine is a T-cell independent immune response, while the immune response to PCV vaccination is a T-cell dependent response that produces memory B-cells and reduces carriage of the bacteria in the respiratory track. The PPSV23 does not reduce bacterial carriage.
Yes. Death as a result of fulminant hepatic failure is rare, however, older age (over 40 years) and preexisting chronic liver disease increases the risk of severe disease and death from hepatitis A. The person-to-person U.S. multistate outbreaks that began in 2016 have disproportionately affected adults with chronic liver disease and other health problems related to drug use and unstable housing. From 2016 through June 2023, CDC received reports of nearly 45,000 cases of acute HAV infection. Of these, approximately 61% have been hospitalized and nearly 1% (more than 420 people) have died.
Treatment with antibiotics is not a valid reason to defer vaccination. If the child or adult is otherwise well, or has only a minor illness, vaccines should be administered. But if the person has a moderate or severe acute illness (regardless of antibiotic use) vaccination may be deferred until the person’s condition has improved.
ACIP recommendations and package inserts do not always match. Occasionally, ACIP may use different data to formulate its recommendations, or try to add flexibility to its recommendations (as was the case in this situation), which results in a recommendation different than the package insert. Published recommendations of national advisory groups (such as ACIP or AAP’s Committee on Infectious Diseases) should be considered equally as authoritative as those on the package insert. You should consider 8 months 0 days as the maximum age for a dose of rotavirus vaccine.
In June 2021, ACIP voted to recommend Dengvaxia for routine use in children age 9 through 16 years with laboratory-confirmed previous dengue virus infection and living in areas where CDC has classified dengue as endemic. The recommendation is only for persons with confirmed previous DENV infection because Dengvaxia is associated with an increased risk for severe dengue in those who experience their first natural infection (i.e., primary infection) after vaccination.
The vaccine is not approved for use in U.S. travelers who are visiting but not living in an area where dengue is common.
The most current ACIP recommendations for Dengvaxia are available at www.cdc.gov/mmwr/volumes/70/rr/pdfs/rr7006a1-H.pdf.
CDC has developed a pre-vaccination checklist for evaluating whether a child should receive Dengvaxia: www.cdc.gov/dengue/resources/DVBD_FS_Vaccination_Checklist-508.pdf.
Fainting is most commonly reported in adolescents, according to the Vaccine Adverse Event Reporting System. One study showed that 62% of all fainting reports to VAERS were among adolescents 11 to 18 years old; however, due to the limitations of VAERS, we cannot use this system to determine how frequently fainting occurs after vaccination.
