Issue 980: February 22, 2012

Ask the Experts: CDC Experts Answer Your Questions

All the Ask the Experts questions and answers in this edition of IAC Express pertain to new ACIP recommendations or they are frequently asked questions. Almost all of them were included in the February 2012 issue of Needle Tips.

IAC extends thanks to our experts, medical epidemiologist Andrew T. Kroger, MD, MPH; nurse educator Donna L. Weaver, RN, MN; medical officer Iyabode Akinsanya-Beysolow, MD, MPH; and medical epidemiologist William L. Atkinson, MD, MPH. All are with the National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC).

Questions and Answers
Q: Is it true that ACIP no longer specifies a time interval between administering doses of Td and Tdap to teens and adults?

A: In January 2011, CDC issued updated ACIP recommendations on the use of Tdap vaccine. They clearly state that pertussis vaccination, when indicated, should not be delayed and that Tdap should be administered regardless of the interval since the last tetanus- or diphtheria-toxoid-containing vaccine was given. This means that if Td was administered inadvertently when Tdap was indicated, the dose of Tdap can be given on the same day the dose of Td was given.

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Q: If a teen or adult patient received a dose of Td vaccine 2 years ago, should I wait approximately 8 more years before administering a dose of Tdap to the patient?

A: No. ACIP recommends that people age 11 through 64 who have not yet received Tdap receive their one-time Tdap dose now. ACIP specifies no waiting interval between administering Td and Tdap to anyone in this age group. Adults age 65 years and older do not need to delay Tdap vaccination following Td either.

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Q: If a teen or adult mistakenly received a dose of Td when they should have received Tdap, what is the optimal time to give the missing Tdap dose?

A: As soon as possible, even if it is the same day.

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Q: Is there any reason not to administer Tdap vaccine to adults age 65 and older who want the vaccine but are not in contact with an infant? It seems like it would be a good idea to vaccinate them to protect them, their family, and their community from pertussis.

A: No medical reason exists for withholding Tdap from adults age 65 and older unless they have a medical contraindication.

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Q: We intend to start vaccinating family contacts of pregnant women with Tdap to protect the newborn. Can you tell me how long it takes for the Tdap vaccine to provide protection?

A: To best protect infants, CDC recommends that teens and adults who haven't been vaccinated receive Tdap 2 weeks or more before having contact with an infant.

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Q: Since we know that children with functional or anatomic asplenia are at high risk for contracting Neisseria meningitidis, why aren’t they included in the latest recommendations to vaccinate certain high-risk children against meningococcal disease beginning at age 9 months?

A: Though what you say is true, these children are also at higher risk of Streptococcus pneumoniae. Data show that the MCV4-D vaccine (Menactra; sanofi pasteur) may interfere with the immunologic response to PCV13 if these two vaccines are given too close together. Therefore, ACIP recommends that MCV4 vaccination be delayed until age 2 years to ensure that these children get age-appropriate vaccination with PCV13, and to improve the likelihood that these children are not vaccinated simultaneously with PCV13 and MCV4.

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Q: Can we vaccinate a 2-year-old boy with functional or anatomic asplenia against meningococcal disease if he has not completed a series of PCV13?

A: You should first be certain that he is up to date with PCV13 vaccine before you vaccinate him with MCV4. If you are going to give him MCV4-D (Menactra; sanofi pasteur), you need to wait at least 4 weeks after he completes the PCV13 series before giving him the MCV4-D. There is no similar space consideration if MCV4-CRM (Menveo; Novartis) is used; it may be given simultaneously with PCV13 or at any interval since receipt of PCV13.

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Q: When people are in their 80s, is it still recommended for them to get the shingles vaccine? I've heard it doesn't work as well in the elderly.

A: ACIP recommends the vaccine for everyone age 60 and older, even though the vaccine's efficacy decreases with the recipient's age. The clinical trials found approximately an 18% efficacy rate in people age 80 and older as compared with 64% efficacy in people age 60 through 69 years (see pages 13–14 of the ACIP recommendations on herpes zoster). In general, with increasing age at vaccination, the vaccine was more effective in reducing the severity of zoster and post-herpetic neuralgia than in reducing the occurrence of zoster itself.

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Q: Occasionally we have asplenic adult patients who want to get the Hib vaccine. We know it’s given only to infants and young children, but what about using it in this situation?

A: Although the vaccine is not routinely recommended for adults, CDC states in the General Recommendations on Immunization: “No efficacy data are available on which to base a recommendation for use of Hib vaccine for older children and adults with the chronic conditions that are associated with an increased risk for Hib disease. Administering 1 dose of Hib vaccine to these patients who have not previously received Hib vaccine is not contraindicated.” For additional information, consult page 22 of the General Recommendations, published January 2011.

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Q: ACIP and CDC’s Vaccine Storage and Handling Guide say that refrigerated vaccines should be stored between 35°–46°F, but some vaccine package inserts list 36°–46°F as the proper range. Should I use 35°F or 36°F as the low boundary of the range?

A: On the Celsius scale, the appropriate storage range for refrigerated vaccines is 2°C–8°C. Because 2°C converts to 35.6°F, some manufacturers have rounded the Fahrenheit reading to 36°F. However, 35°F is still considered acceptable for storage of any refrigerated vaccine. Providers should make an effort to store vaccines toward the midpoint of the range (approximately 40°F or 5°C) rather than at either end of the scale.

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Q: What should I do if my thermometer indicates my refrigerated vaccine has been stored between 32°–34°F? Since the vaccine wasn’t “frozen,” will it be OK to use? And what about people who received the vaccine before we discovered the temperature excursion—will we need to revaccinate them?

A: This is a complex question that requires case-by-case review. First, while you’re assessing the situation, return the vaccine to proper storage temperatures and mark it “Do Not Use.” Then, contact your state or local immunization program or the appropriate vaccine manufacturer(s) to discuss the potential usability of the vaccine. They will need to consider several variables related to vaccine storage conditions. For example, their guidance will be affected by the accuracy of the thermometer, whether the thermometer probe was in a liquid or was reading the temperature of the air, the type of vaccine involved, the length of time of the excursion, etc.

In general, if it can be reliably determined that the vaccine in question was not stored below 32°F and the manufacturer’s stability data concurs, most immunization programs and vaccine manufacturers would not recommend wasting the vaccine or revaccinating recipients.

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Q: Does the federal law that requires providing patients with VISs apply when administering influenza vaccine to employees and volunteers in hospitals or other workplaces?

A: If a vaccine is covered under the National Childhood Vaccine Injury Act—and almost all vaccines routinely administered to adults are (with the exception of PPSV and zoster)–it is mandatory under federal law to give the VIS for that vaccine to the vaccinee. Therefore, when you give influenza vaccine to employees and staff, you are required by law to provide them with a VIS.
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Q: If you place a needle on a pre-filled syringe and then don't administer the vaccine, how long can you store the pre-filled syringe with the needle attached?

A: In general, a vaccine should not be prepared until the provider is ready to administer it to a patient. This is because once the syringe cap is removed or a needle is attached, the sterile seal is broken. However, if a sterile seal has been broken, staff should be sure to maintain the syringe at the appropriate temperature and either use it or discard it at the end of the clinic day.

CDC's Pink Book has a new chapter about vaccine storage and handling.

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Q: I have a child patient traveling to a country for which Japanese Encephalitis (JE) vaccine is recommended. What can I do to protect her now that JE-Vax is no longer available?

A: No licensed JE vaccine is available for children younger than 17 years now that the current supply of JE-Vax has expired. Three options exist for U.S. healthcare providers interested in obtaining JE vaccine for pediatric patients they judge to be at risk: (1) enroll children in the ongoing clinical trial, (2) administer JE-VC (Ixiaro) off-label, or (3) advise the child's parents to have the child receive JE vaccine at an international travelers' health clinic in Asia. For more information, see the MMWR article Update on Japanese Encephalitis Vaccine for Children–United States, May 2011.

Travelers, including children, should also use personal protective measures to avoid mosquito bites and reduce the risk for JE and other vector-borne infectious diseases. Such measures include using insect repellent, permethrin-impregnated clothing and bed nets, and staying in accommodations with screened or air-conditioned rooms. For details, refer page 17 of the ACIP statement Japanese Encephalitis Vaccines published in March 2010.

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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 guarantee that we will print your specific question in the 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 co-workers and suggest they 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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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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