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Issue 1428: May 30, 2019
Ask the Experts: CDC Experts Answer Your Questions
As a thank-you to our loyal IAC Express readers, we periodically publish extra editions such as this one, with new and updated "Ask the Experts" Q&As answered by CDC experts. The Q&As in this issue all relate to measles and MMR vaccination, in light of the current measles outbreaks.
IAC extends thanks to our experts: Andrew T. Kroger, MD, MPH; Mark S. Freedman, DVM, MPH, DACVPM; Tina S. Objio, MSN, MHA, RN; Candice L. Robinson, MD, MPH; Raymond A. Strikas, MD, MPH, FACP, FIDSA; and JoEllen Wolicki, BSN, RN, all from the National Center for Immunization and Respiratory Diseases, CDC.
Measles and MMR Vaccination
Measles and MMR Vaccination
Q: What is the current situation with measles in the U.S.?
A: From January 1–May 24, 2019, 940 cases of measles from 26 states have been reported to CDC. CDC measles surveillance updates can be found at www.cdc.gov/measles/cases-outbreaks.html. The 940 cases of measles is the largest number of cases reported in the U.S. in a single year since 1994.
Among reported cases through May 17, 90% were unvaccinated or their vaccination status was unknown. Fifty-five (6%) cases were acquired outside of the U.S. (international importations) and 825 (94%) were acquired in the U.S. Most cases (94%) were related to outbreaks and 75% were related to outbreaks in New York City and New York State.
During the same time period, the median age among people with measles was 6 years old. Thirteen percent were younger than 12 months old, 10% were 12–15 months, 23% were 16 months–4 years, 28% were 5–17 years, 10% were 18–29 years, 12% were 30–49 years, and 4% were 50 years and older. Overall, 9% of patients with measles were hospitalized.
Information on the measles outbreak situation through May 17 can be found at www.emergency.cdc.gov/coca/ppt/2019/slides_052119_Measles.pdf.
Among 44 imported cases described in an MMWR article published May 3, 40 (91%) were in unvaccinated people and people whose vaccination status was unknown; 34 of the 44 imported measles cases were among U.S. citizens. Source countries included Philippines (14 cases), Ukraine (8), Israel (5), Thailand (3), Vietnam (2), Germany (2), and one each from Algeria, France, India, Lithuania, Russia, and the United Kingdom. The number of different source countries highlights the global increase in measles worldwide.
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Q: What are the current recommendations for the use of MMR vaccine?
A: 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. 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 (evidence of immunity is defined as documented receipt of 1 dose [2 doses 4 weeks apart if high risk] of live measles virus-containing vaccine, laboratory evidence of immunity or laboratory confirmation of disease, or birth before 1957) should get 1 dose of MMR vaccine unless the adult is in a high-risk group. High-risk people need 2 doses and include healthcare personnel, international travelers, and students attending post-high school educational institutions.
Live attenuated measles vaccine became available in the U.S. in 1963. An ineffective, inactivated measles vaccine was also available in the U.S. in 1963–1967. Combined MMR vaccine (MMRII, Merck) was licensed in 1971. 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. At the discretion of the state public health department, anyone exposed to measles in an outbreak setting can receive an additional dose of MMR vaccine even if they are considered completely vaccinated for their age or risk status.
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Q: What are the signs and symptoms healthcare providers should look for in diagnosing measles?
A: Healthcare providers should suspect measles in patients with a febrile rash illness and the clinically compatible symptoms of cough, coryza (runny nose), and/or conjunctivitis (red, watery eyes).
A clinical case of measles is defined as an illness characterized by
- a generalized rash lasting 3 or more days, and
- a temperature of 101°F or higher (38.3°C or higher), and
- cough, coryza, and/or conjunctivitis.
Koplik spots, a rash present on mucous membranes, are considered pathognomonic for measles. Koplik spots occur from 1 to 2 days before the measles rash appears to 1 to 2 days afterward. They appear as punctate blue-white spots on the bright red background of the buccal mucosa. Pictures of measles rash and Koplik spots can be found at www.cdc.gov/measles/about/photos.html.
Providers should be especially aware of the possibility of measles in people with fever and rash who have recently traveled abroad or who have had contact with international travelers or who live in an area with reported cases.
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Q: What should our clinic do if we suspect a patient has measles?
A: Measles is highly contagious. Patients with suspected measles should be isolated for 4 days after they develop a rash. Airborne precautions should be followed in healthcare settings by all healthcare personnel. The preferred placement for patients who require airborne precautions is in a single-patient airborne infection isolation room.
Providers should immediately isolate and report suspected measles cases to their local health department and obtain specimens for measles testing, including serum sample for measles serologic testing and a throat swab (or nasopharyngeal swab) for viral confirmation.
Measles is a nationally notifiable disease in the U.S.; healthcare providers should report all cases of suspected measles to public health authorities within 24 hours to help reduce the number of secondary cases.
More information on measles disease, diagnostic testing, and infection control can be found at www.cdc.gov/measles/hcp/index.html.
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Q: When is it appropriate to use MMR vaccine for post-exposure prophylaxis?
A: MMR vaccine given within 72 hours of initial measles exposure can reduce the risk of getting sick or reduce the severity of symptoms. Another option is giving exposed, measles-susceptible people immunoglobulin (IG) within six days of exposure. Do not administer MMR vaccine and IG simultaneously, as this practice invalidates the vaccine.
Information on post-exposure prophylaxis for measles can be found in the 2013 ACIP guidance at www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm.
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Q: What is considered acceptable evidence of immunity?
A: Acceptable presumptive evidence of immunity against measles includes at least one of the following:
- written documentation of adequate vaccination:
- one or more doses of a measles-containing vaccine administered on or after the first birthday for preschool-age children and adults not at high risk
- two doses of measles-containing vaccine for school-age children, adolescents, and adults at high risk, including college students, healthcare personnel, and international travelers
- laboratory evidence of immunity
- laboratory confirmation of measles (verbal history of measles does not count)
- birth before 1957
Although birth before 1957 is considered acceptable evidence of measles immunity, healthcare facilities should consider vaccinating unvaccinated personnel born before 1957 who do not have other evidence of immunity with 2 doses of MMR vaccine (minimum interval 28 days).
During an outbreak of measles or mumps, healthcare facilities should recommend 2 doses of MMR vaccine at the appropriate interval for unvaccinated healthcare personnel regardless of birth year if they lack laboratory evidence of measles immunity.
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Q: For which adults are 0, 1, or 2 doses of MMR vaccine recommended to prevent measles?
A: Zero, 1, or 2 doses of MMR vaccine are needed for the adults described below.
Zero doses:
- adults born before 1957 except healthcare personnel*
- adults born 1957 or later who are at low risk (i.e., not an international traveler or healthcare worker) and who have received one or more documented doses of live measles vaccine
- adults with laboratory evidence of immunity or laboratory confirmation of measles
One dose of MMR vaccine:
- adults born 1957 or later who are at low risk (i.e., not an international traveler, healthcare worker, or person attending college or other post-high school educational institution) and have no documented vaccination with live measles vaccine and no laboratory evidence of immunity or prior measles infection
Two doses of MMR vaccine:
- high-risk adults without any prior documented live measles vaccination and no laboratory evidence of immunity or prior measles infection, including:
- healthcare personnel*
- international travelers born in 1957 or later
- persons attending colleges and other post-high school educational institutions
Persons 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, should be revaccinated with either one (if low-risk) or two (if high-risk) doses of MMR vaccine.
* Healthcare personnel born before 1957 should be considered for MMR vaccination in the absence of an outbreak, but are recommended for MMR vaccination during outbreaks.
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Q: Given the outbreaks of measles in the U.S., should all healthcare personnel, including those born before 1957, have 2 doses of MMR vaccine?
A: Although birth before 1957 is considered acceptable evidence of measles immunity for routine vaccination, healthcare facilities should consider vaccinating unvaccinated healthcare personnel (HCP) born before 1957 who do not have laboratory evidence of measles immunity, laboratory confirmation of disease, or vaccination with 2 appropriately spaced doses of MMR vaccine.
However, during an outbreak of measles, all healthcare personnel, including those born before 1957, are recommended to have 2 doses of MMR vaccine at the appropriate interval if they lack laboratory evidence of measles.
Healthcare facilities should check with their state or local health department’s immunization program for guidance. Access contact information from the Association of Immunization Manager's website.
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Q: Would you consider healthcare personnel with 2 documented doses of MMR vaccine to be immune even if their serology for 1 or more of the antigens comes back negative?
A: Yes. Healthcare personnel (HCP) with 2 documented doses of MMR vaccine are considered to be immune regardless of the results of a subsequent serologic test for measles, mumps, or rubella. Documented age-appropriate vaccination supersedes the results of subsequent serologic testing. In contrast, HCP who do not have documentation of MMR vaccination and whose serologic test is interpreted as "indeterminate" or "equivocal" should be considered not immune and should receive 2 doses of MMR vaccine (minimum interval 28 days). ACIP does not recommend serologic testing after vaccination. For more information, see ACIP's recommendations on the use of MMR vaccine at www.cdc.gov/mmwr/pdf/rr/rr6204.pdf, page 22.
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Q: Have recommendations for MMR vaccination of children or adults changed in light of the current outbreak?
A: No. The most recent CDC recommendations for MMR vaccination were published in 2013 and can be found at www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm.
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Q: How soon can we give the second dose of MMR vaccine to a child vaccinated at 12 months old?
A: For routine vaccination, children without contraindications to MMR vaccine should receive 2 doses of MMR vaccine with the first dose at age 12–15 months old and the second dose at age 4–6 years old. The minimum interval is 28 days for dose 2. If you have an outbreak in your community or a child is traveling internationally, then consider using the minimum interval instead of waiting until age 4–6 years old for dose 2.
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Q: If there is an outbreak in my area, can we vaccinate children younger than 12 months?
A: MMR can be given to children as young as 6 months of age who are at high risk of exposure such as during international travel or a community outbreak. However, doses given BEFORE 12 months of age cannot be counted toward the 2-dose series for MMR.
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Q: If we give a child a dose of MMR vaccine at 6 months of age because they are in a community with cases of measles, when should we give the next dose?
A: The next dose should be given at 12 months of age. The child will also need another dose at least 28 days later. For the child to be fully vaccinated, they need to have 2 doses of MMR vaccine given when the child is 12 months of age and older. A dose given at less than 12 months of age does not count as part of the MMR vaccine two-dose series.
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Q: Do any adults need “booster” doses of MMR vaccine to prevent measles?
A: No. Adults with evidence of immunity do not need any further vaccines. No “booster” doses of MMR vaccine are recommended for either adults or children. They are considered to have life-long immunity once they have received the recommended number of MMR vaccine doses or have other evidence of immunity.
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Q: A patient who was born before 1957 and is not a healthcare worker wants to get the MMR vaccine before international travel. Does he need a dose of MMR?
A: No. Before implementation of the national measles vaccination program in 1963, virtually every person acquired measles before adulthood. So, this patient is considered immune based on their birth year.
Routine testing of patients born before 1957 for measles-specific antibody is not recommended by CDC.
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Q: Under what circumstances should adults be considered for testing for measles-specific antibody prior to getting vaccinated?
A: Adults without evidence of immunity and no contraindications to MMR vaccine can be vaccinated without testing. Only adults without evidence of immunity might be considered for testing for measles-specific IgG antibody, but testing is not needed prior to vaccination.
CDC does not recommend measles antibody testing after MMR vaccination to verify the patient’s immune response to vaccination.
Two documented doses of MMR vaccine given on or after the first birthday and separated by at least 28 days is considered proof of measles immunity, according to ACIP. Documentation of appropriate vaccination supersedes the results of serologic testing for measles, mumps, rubella, and varicella.
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Q: What are the contraindications and precautions for MMR vaccine?
A: Contraindications:
- history of a severe (anaphylactic) reaction to any vaccine component (e.g., neomycin) or following a previous dose of MMR
- pregnancy
- severe immunosuppression from either disease or therapy
Precautions:
- receipt of an antibody-containing blood product in the previous 3–11 months, depending on the type of blood product received. See www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html, Table 3–5 for more information on this issue
- moderate or severe acute illness with or without fever
- history of thrombocytopenia or thrombocytopenic purpura
Important details about the contraindications and precautions for MMR vaccine are in the current MMR ACIP statement, available at www.cdc.gov/mmwr/pdf/rr/rr6204.pdf.
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Q: We have many patients who are immunocompromised and cannot get the MMR vaccine. How should we advise our patients?
A: People with medical conditions that contraindicate measles immunization depend on high MMR vaccination coverage among those around them. To help prevent the spread of measles virus, make sure all your staff and patients who can be vaccinated are fully vaccinated according to the U.S. immunization schedule. Also, encourage patients to remind their family members and other close contacts to get vaccinated if they are not immune.
If patients who cannot get MMR vaccine are exposed to measles, CDC has guidelines for immune globulin for post-exposure prophylaxis which can be found at www.cdc.gov/mmwr/preview/mmwrhtml/rr6204a1.htm.
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Q: What is the recommended length of time a woman should wait after receiving rubella (MMR) vaccine before becoming pregnant?
A: Although the MMR vaccine package insert recommends a 3-month deferral of pregnancy after MMR vaccination, ACIP recommends deferral of pregnancy for 4 weeks. For details on this issue, see ACIP's Control and Prevention of Rubella: Evaluation and Management of Suspected Outbreaks, Rubella in Pregnant Women, and Surveillance for Congenital Rubella Syndrome.
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Q: How soon after delivery can MMR be given to the mother?
A: MMR can be administered any time after delivery. The vaccine should be administered to a woman who is susceptible to either measles, mumps, or rubella before hospital discharge, even if she has received RhoGam during the hospital stay, leaves in less than 24 hours, or is breastfeeding.
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Q: How should teenage girls and women of child-bearing age be screened for pregnancy before MMR vaccination?
A: ACIP recommends that women of childbearing age be asked if they are currently pregnant or attempting to become pregnant. Vaccination should be deferred for those who answer "yes." Those who answer "no" should be advised to avoid pregnancy for 4 weeks following vaccination. Pregnancy testing is not necessary.
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Q: If a pregnant woman inadvertently receives MMR vaccine, how should she be advised?
A: No specific action needs to be taken other than to reassure the woman that no adverse outcomes are expected as a result of this vaccination. MMR vaccination during pregnancy is not a reason to terminate the pregnancy. You should consult with others in your healthcare setting to identify ways to prevent such vaccination errors in the future. Detailed information about MMR vaccination in pregnancy is included in the most recent MMR ACIP statement, available at www.cdc.gov/mmwr/pdf/rr/rr6204.pdf.
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How to submit a question to Ask the Experts
IAC works with CDC to compile new Ask the Experts Q&As for our publications based on commonly asked questions. We also consider the need to provide information about new vaccines and recommendations. Most of the questions are thus a composite of several inquiries.
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