Issue 1,710: August 29, 2023
Ask the Experts: Answers Questions
about Vaccine Storage and Handling, Polio, and
Meningococcal Vaccines 

As an additional service to IZ Express readers, we periodically publish special editions such as this one, providing you with new and updated Ask the Experts questions and answers from’s experts. This issue includes 4 Q&As about vaccine storage and handling, 3 Q&As about polio vaccination, and 4 Q&As about meningococcal vaccination.  

You can find all of these questions and answers, plus more than a thousand others about vaccines and vaccine administration, on our "Ask the Experts" gateway page at's team of experts includes Kelly L. Moore, MD, MPH (team lead), Carolyn B. Bridges, MD, FACP, and Iyabode Beysolow, MD, MPH.

Storage and Handling Questions

Storage and Handling Questions

Q: Where can I get the most up-to-date information about vaccine storage and handling?

A: CDC publishes and routinely updates a comprehensive Vaccine Storage and Handling Toolkit covering topics such as vaccine storage units, temperature monitoring devices, inventory management, vaccine transport, and emergency vaccine storage and handling. The toolkit also contains troubleshooting guides to assist with vaccine storage unit issues or temperature excursions. This terrific resource, along with other vaccine storage and handling resources from CDC, is available online at
In addition, maintains many free, downloadable materials at

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Q: When the expiration date of a vaccine indicates a month and year, does the vaccine expire on the first or last day of the month?

A: Vaccine may be used through the last day of the month indicated on the expiration date. After that, do not use it. Monitor your vaccine supply carefully so that vaccines do not expire. The CDC encourages providers to monitor and rotate vaccine supply routinely in storage units so that vaccines with the earliest expiration dates are placed in front of and used ahead of those with later expiration dates to avoid wastage.

Q: What is a temperature excursion?

A: Any temperature reading outside the recommended range for vaccine storage is a temperature excursion. However, it is generally the total amount of time, or cumulative time, out of range that affects the viability of vaccine. Any time appropriate vaccine storage temperatures are in question, stop giving vaccinations and contact your state immunization program and/or the vaccine manufacturer for further guidance about whether or not a vaccine may be used. The CDC Vaccine Storage and Handling Toolkit contains detailed guidance on the management of a temperature excursion.

See, pages 15–17. Additional information for COVID-19 and mpox vaccine temperature excursions is available in the addendum at the end of the toolkit.

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Q: What is NSF/ANSI 456 certification?

A: A refrigerator or freezer that is NSF-certified for vaccine storage means the units have been tested and certified to meet the NSF/American National Standards Institute (ANSI) 456 standard. The NSF/ANSI 456 standard (or simply "NSF 456" standard) defines the criteria for construction and performance of vaccine refrigerators and freezers used in healthcare settings where vaccines are given. These criteria were developed through a collaboration with NSF, CDC, healthcare providers, public health agencies, equipment manufacturers, and vaccine manufacturers, including experts from 
The NSF 456 certification is a voluntary standard. CDC does not require NSF-certified units for vaccine storage in the Vaccines for Children program or any other federal program. Not all storage units capable of reliably storing vaccines have this certification; however, all storage unit models with this certification have been designed and proven to properly store vaccines under a range of normal clinic conditions. NSF-certified units would be good options for clinic staff to consider when purchasing vaccine storage units.

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Q: We have a small office with limited space for a vaccine storage unit. If dormitory-style refrigerators are not an option, what can we use?

A: A "dormitory-style" refrigerator is a small combination refrigerator/freezer unit that is outfitted with one exterior door and an evaporator plate (cooling coil), which is usually located inside an icemaker compartment (freezer) within the refrigerator. This type of unit has severe temperature control and stability issues. However, there are compact refrigerators or freezers noted as "pharmaceutical grade" or "purpose-built for vaccine storage" that have been engineered to maintain even temperatures throughout the unit, and these may meet the needs of a small office. In general, the unit you select must be large enough to store the year's largest vaccine inventory without crowding and to store water bottles (in a refrigerator) and frozen coolant packs (in a freezer) to minimize temperature fluctuations. One way to assure that the unit you purchase will reliably maintain proper vaccine storage temperatures is to look for a unit labeled as meeting the NSF/ANSI 456 certification standard for vaccine storage. This voluntary certification indicates that the model has been tested and certified to maintain proper storage conditions under a range of normal clinic conditions.

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Polio Questions

Q: How did ACIP alter its recommendations for polio (IPV) vaccination of unvaccinated or incompletely vaccinated adults in June 2023?

A: 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.

Q: Do adults 19 years and older who completed a IPV vaccine primary series as children need to get a booster dose?

A: 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:

  • Travelers who are going to countries where polio is epidemic or endemic (see polio information for travelers at
  • Laboratory and healthcare workers who handle specimens that might contain polioviruses
  • Healthcare workers or other caregivers who have close contact with a person who could be infected with poliovirus

Q: How do I determine if doses of oral polio vaccine (OPV) administered outside the United States were trivalent OPV?

A: Use the date of administration to make a presumptive determination of what type of OPV was received. Only trivalent doses count as valid for the U.S. polio vaccination schedule.
Trivalent OPV was used throughout the world before April 2016. In April 2016, all countries using tOPV switched to bivalent OPV (bOPV). In addition, some countries also use monovalent OPV (mOPV) during special vaccination campaigns. Doses recorded as bOPV or mOPV, and unspecified OPV doses noted on an immunization record as given during a vaccination campaign, do not count as valid doses for the U.S. polio vaccination schedule.
You may count a record of an “OPV” dose as valid if the dose was administered before April 1, 2016, and was not noted as being administered as part of a mass vaccination campaign. OPV doses administered on or after April 1, 2016, should not be counted as a valid dose for the U.S. polio vaccination schedule.

Meningococcal ACWY Questions

Q: What is the schedule for MenACWY vaccine?

A: All adolescents should receive a dose of MenACWY at age 11 or 12 years. A second (booster) dose is recommended at age 16 years. Adolescents who receive their first dose at age 13 through 15 years should receive a booster dose at age 16 years. The minimum interval between MenACWY doses is 8 weeks. Adolescents who receive a first dose after their 16th birthday do not need a booster dose unless they become at increased risk for meningococcal disease. Colleges may not consider a second dose given even a few days before age 16 years as valid, so keep that in mind when scheduling patients. People age 19 through 21 years are not recommended routinely to receive MenACWY. However, MenACWY may be administered to people age 19 through 21 years as catch-up vaccination for those who have not received a dose after their 16th birthday.

Q: I have a patient with paroxysmal nocturnal hemoglobinuria who is being treated with Soliris (eculizumab). Should he receive meningococcal vaccine?

A: Eculizumab (Soliris) and the related long-acting compound ravulizumab (Ultomiris) bind to C5 and inhibit the terminal complement pathway. People with persistent complement component deficiency due to an immune system disorder or use of a complement inhibitor are at increased risk for meningococcal disease even if fully vaccinated. This patient should be given a series of MenACWY vaccine, MenACWY (2 doses separated by at least 8 weeks) and a 2- or 3-dose series (depending on brand) of MenB vaccine. The patient should receive regular booster doses of MenACWY and MenB as long as he remains at risk: a booster dose of MenACWY every 5 years and a booster dose of MenB one year after completion of the primary series, followed by a booster dose of MenB every 2–3 years thereafter.
Because patients treated with complement inhibitors can develop invasive meningococcal disease despite vaccination, clinicians using Soliris or Ultomiris also may consider antimicrobial prophylaxis for the duration of complement inhibitor therapy.

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Meningococcal B Questions

Q: Who is recommended to be vaccinated against meningococcal B disease?

A: MenB is routinely recommended for these groups:

  • People age 10 years and older who have functional or anatomic asplenia (including sickle cell disease)
  • People age 10 years and older who have persistent complement component deficiency (an immune system disorder) or who take a complement inhibitor such as eculizumab (Soliris, Alexion Pharmaceuticals) or ravulizumab (Ultomiris, Alexion Pharmaceuticals)
  • People age 10 years and older who are exposed during an outbreak caused by serogroup B
  • Microbiologists who work with meningococcal isolates in a laboratory

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 age 16 through 23 years (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.

Q: Are the two MenB vaccines interchangeable?

A: No. The ACIP meningococcal serogroup B vaccine recommendations state that the same vaccine must be used for all doses in the MenB series, including booster doses. If the brand of a previous dose is unavailable or cannot be determined, restart the primary series with the available brand.

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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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