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Issue 1194: July 15, 2015

Ask the Experts: CDC Experts Answer Your Questions

Most of the questions and answers in this edition of IAC Express first appeared in the May 2015 issues of Needle Tips and Vaccinate Adults.

IAC extends thanks to our experts, medical officer Andrew T. Kroger, MD, MPH, and nurse educator Donna L. Weaver, RN, MN, both from the National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC).

MMR Vaccine

Hepatitis B Vaccine   Meningococcal Vaccine Zoster Vaccine Typhoid Vaccine Asplenia and Vaccines

MMR Vaccine
Q: In regard to the current measles outbreak, some people are saying that children who have not had the vaccine should pose no threat to vaccinated people. It is my understanding that during an outbreak, vaccinated people can still contract it. Am I correct?

A: You are correct that vaccinated people can still be infected with infections against which they are vaccinated. No vaccine is 100% effective. Vaccine effectiveness varies from greater than 95% (for diseases such as measles, rubella, hepatitis B) to much lower (influenza this year 23%, and 60% in years with a good match of wild and vaccine viruses, and the acellular pertussis vaccines after 5 years or so provide only about 70% protection). Therefore, we encourage as many people as possible to be vaccinated, to avoid outbreaks, while working towards the development of better vaccines (such as for influenza and pertussis). More information is available for each vaccine and disease at and

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Q: We received a call from a healthcare provider who inadvertently administered MMR vaccine to a woman who was 2 months pregnant. Please advise as to appropriate action steps.

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 alone is not a reason to terminate the pregnancy. You should consult with the provider to determine if there is a way to avoid such vaccination errors in the future. Detailed information about MMR vaccination in pregnancy is included in the most recent MMR ACIP statement, available at

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Q: If a healthcare worker has a documented positive measles serology as evidence of immunity, do they need to wear an N95 mask when caring for a patient with measles?

A: Regardless of presumptive immunity status, all healthcare staff entering the room of a person with measles should use respiratory protection consistent with airborne infection control precautions (use of an N95 respirator or a respirator with similar effectiveness in preventing airborne transmission). Because of the possibility, albeit low, of a laboratory error (or vaccine failure in a person whose presumptive immunity is based on vaccination alone) all healthcare providers should observe airborne precautions in caring for patients with measles. For more information on measles and measles vaccine for healthcare providers, see

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Hepatitis B Vaccine
Q: If an infant got a dose of the adult formulation of hepatitis B vaccine in error, should the dose be counted? When should the next dose be scheduled for this infant? Do we need to be concerned about a possible adverse event?

A: If an infant received an adult dose of hepatitis B vaccine (contains twice the antigen in a dose of the infant/child formulation), the dose can be counted as valid and does not need to be repeated. Hepatitis B vaccine is a very safe vaccine and no unusual adverse events would be expected because of this administration error. The next (age appropriate) dose should be given on the usual schedule.

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Meningococcal  Vaccine
Q: We have a 65-year-old male seeking vaccination due to international travel. Meningococcal polysaccharide vaccine (MPSV4, Menomune, Sanofi Pasteur) is unavailable, and we aren’t sure when we can get it. How should we proceed? Is this a circumstance in which a conjugate vaccine is appropriate at his age?

A: ACIP recommends off-label use of quadrivalent meningococcal conjugate vaccine (MCV4: Menactra, Sanofi Pasteur; Menveo, GlaxoSmithKline) in adults age 56 years and older who (1) were vaccinated previously with MCV4 and now need revaccination or (2) are recommended to receive multiple doses (e.g., adults with asplenia, microbiologists working with Neisseria meningitidis). Although MPSV4 is recommended in the situation you describe, it is acceptable to use MCV4 if MPSV4 is not available.

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Zoster Vaccine
Q:  My patient is a 66-year-old male with a condition that requires treatment with intravenous immune globulin (IVIG) once a month. Can he receive zoster vaccine?

A: Yes. The concern about interference by circulating antibody (from the IVIG), which we have for varicella vaccine, does not apply to zoster vaccine. The amount of antigen in zoster vaccine is high enough to offset any effect of circulating antibody. Also, studies of zoster vaccine were performed on patients receiving antibody-containing blood products with no appreciable effect on efficacy.

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Typhoid Vaccine
Q: A new typhoid ACIP statement was recently published. Are there new recommendations for the use of typhoid vaccines?

A: A revised typhoid ACIP statement was published in March 2015. The document provides an update of the epidemiology of typhoid fever and an update on typhoid vaccine effectiveness and safety. There are no substantive changes in the recommendations for use of typhoid vaccines. The new document is available at, pages 305–308.
In the previous typhoid ACIP statement (1994) it was recommended to defer the use of live oral typhoid vaccine for 24 hours following a dose of the anti-malarial drug mefloquine. The revised document states that mefloquine and the antimalarial agents chloroquine and the combinations atovaquone/proguanil and pyrimethamine/sulfadoxine can be administered at the same time as oral typhoid vaccine.

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Asplenia and Vaccines
Q: Do any of the bacterial vaccines that are recommended for people with functional or anatomic asplenia need to be given before splenectomy? Do the doses count if they are given during the 2 weeks prior to surgery?

A: Pneumococcal conjugate vaccine (PCV13), Haemophilus influenzae type b vaccine (Hib), meningococcal conjugate vaccine (MCV4), and meningococcal serogroup B vaccine (MenB) should be given 14 days before splenectomy, if possible. Doses given during the 2 weeks (14 days) before surgery can be counted as valid. If the doses cannot be given prior to the splenectomy, they should be given as soon as the patient’s condition has stabilized after surgery.

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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.

You can email your question about vaccines or immunization to IAC at

As we receive hundreds of emails each month, we cannot promise that we will print your specific question in our Ask the Experts feature. However, you will get an answer.

You can also email CDC's immunization experts directly at There is no charge for this service.

If you have a question about IAC materials or services, email

Please forward these Ask the Experts Q&As to your colleagues and ask them to subscribe to IAC Express.

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About IZ Express

IZ Express is supported in part by Grant No. 1NH23IP922654 from CDC’s National Center for Immunization and Respiratory Diseases. Its contents are solely the responsibility of and do not necessarily represent the official views of CDC.

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ISSN 2771-8085

Editorial Information

  • Editor-in-Chief
    Kelly L. Moore, MD, MPH
  • Managing Editor
    John D. Grabenstein, RPh, PhD
  • Associate Editor
    Sharon G. Humiston, MD, MPH
  • Writer/Publication Coordinator
    Taryn Chapman, MS
    Courtnay Londo, MA
  • Style and Copy Editor
    Marian Deegan, JD
  • Web Edition Managers
    Arkady Shakhnovich
    Jermaine Royes
  • Contributing Writer
    Laurel H. Wood, MPA
  • Technical Reviewer
    Kayla Ohlde

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