Experts Highlight RSV Vaccination Strategies: Maternal Immunization, Infant Protection, and Clinical Considerations for 2025

In an interview with Pharmacy Times®, Anita Siu, PharmD, BCPPS, vice chair of teaching and learning, clinical professor, and director of faculty mentoring at the Ernest Mario School of Pharmacy, Rutgers, and Mary Bridgeman, PharmD, BCPS, BCGP, FASCP, FCCP, FNAP, clinical professor at the Ernest Mario School of Pharmacy, Rutgers, discussed respiratory syncytial virus (RSV) vaccination strategies, including storage, handling, and administration guidelines for different vaccine types like Abrysvo (Pfizer), mRESVIA (ModernaTX), and Nirsevimab (AstraZeneca). Siu and Bridgeman highlighted specific considerations for older adults and pregnant women, noting increased risks for those with chronic conditions and the importance of timing vaccine administration during the RSV season. Bridgeman emphasized a safety alert from the FDA regarding a potential increased risk of Guillain-Barré Syndrome with certain RSV vaccines. Siu also provided detailed insights into maternal vaccination and infant protection, stressing the need to follow CDC guidelines for proper immunization.

Pharmacy Times: Are there any specific considerations for the preparation, storage, and handling of RSV vaccines according to the 2025 immunization guidelines?

Mary Bridgeman, PharmD, BCPS, BCGP, FASCP, FCCP, FNAP: I'm not sure if these are reflected in the immunization guidelines, but certainly the manufacturers of the RSV vaccines have recommendations for product handling that pharmacists who are administering these vaccines should be familiar with. It's the prefusion F protein vaccines, which are Abrysvo and Arexvy, that need to be stored under refrigeration and require reconstitution with the supplied diluent prior to administration. The prefusion mRNA vaccine, which goes by the brand name mRESVIA, is stored frozen and then needs to be thawed prior to administration. That one is available as a prefilled syringe. A little bit different handling and a little bit different storage considerations based on the type of vaccine we're talking about.

Anita Siu, PharmD, BCPPS: I also wanted to comment on the Nirsevimab, which is actually not a vaccine itself. It's actually considered an immunization. The reason for that is that it's a recombinant human immunoglobulin. It works by IgG1 kappa, its monoclonal antibody, so it is very different from our other vaccines that are currently available. This one is currently a passive immunization. It can be administered simultaneously with other childhood vaccines, and just like vaccines, it's not used for treatment. It's used for prophylaxis of RSV, specifically in neonates and infants born during the first RSV season. It can be used in children up to 24 months who remain vulnerable or at high risk during their second RSV season. Now very interesting, how that is particularly stored is that they're readily available as prefilled syringes, and they're actually required to be stored under refrigeration between 2 to 8 degrees. I agree with Mary as well; always refer to the manufacturer recommendations and how to store these vaccines or immunizations, because we want to make sure that the cold chain remains intact.

Pharmacy Times: According to the 2025 guidelines, are there any specific older adult populations with unique considerations or contraindications for RSV vaccination?

Bridgeman: I think that older adults really are at an increased risk for experiencing complications associated with RSV infection caused by a common respiratory virus. Really, those individuals, especially with chronic lung diseases like COPD and asthma, with chronic heart disease, and who are immunocompromised, are particularly vulnerable and at a high risk of complications should they contract this viral illness. Regarding contraindications, I think it's important to recall that universal vaccine contraindication, we don't immunize with the RSV vaccines for those with a history of anaphylaxis to a previous dose of an RSV vaccine or to a vaccine component, and that really applies in this setting. Fortunately, the current recommendation is that individuals need just 1 dose of the RSV vaccine. It is not a seasonal vaccine right now; the recommendation is just a single dose at some point in their lives. I will point out that the FDA issued a safety alert in January of 2025 regarding an increased risk of Guillain-Barré Syndrome within 42 days of administration of the prefusion F protein-based RSV vaccines. That was based on some post-marketing observational data. As pharmacists, I think we need to keep an eye on these warnings accordingly. This is a particularly significant safety concern, so it's something that we will certainly keep an eye on.

Pharmacy Times: What are the implications for a maternal RSV vaccine? How does this protect the infant from RSV infection?

Siu: That's an excellent question. The maternal RSV vaccine, and I'm going to use the brand name, particularly in this, because we use RSV vaccines, but there's actually only one that is currently recommended during pregnancy, and that's known as Abrysvo. Abrysvo, in particular, is given during the RSV season to people who are between 32 and 36 weeks pregnant. The nice thing about giving the RSV vaccine in pregnant women is that if the mother does receive the vaccine and it's less than 14 days prior to their delivery, they then have to administer 1 dose of Nirsevimab, which we talked about earlier, within one week of birth in the hospital or the outpatient setting. However, if the mother does receive the RSV vaccine at least 14 days prior to delivery, the Nirsevimab is not needed, but can be considered in rare consensus at the discretion of the health care provider. Which is important to note, because if mothers are receiving the RSV vaccine, and we all know that vaccines usually take about 2 weeks to actually effectively work. With that being said, antibodies do get into the newborn for the baby, and they do not need Nirsevimab, particularly RSV immunization. The key thing is really timing. So timing of RSV immunization for infants and pregnant people can be a bit confusing, but it doesn't have to be confusing. The CDC actually has a very nice flow diagram. When we recommend the RSV vaccine in pregnant women, it is recommended, like I mentioned earlier, during the weeks of 32 to 36 weeks of pregnancy, starting in September, because we know right now these RSV vaccines are only recommended during the RSV season. It begins in September, and it ends in January for pregnant women. Some of these things are important because with Nirsevimab for infants, it's actually not recommended until October to the end of March, which is a little different than when we recommend the RSV vaccines for pregnant women. I would recommend that health care providers and individuals double-check. The CDC has a beautiful flow diagram. There are other variations of this, but just keep in mind, they're not interchangeable. They do have some overlap, but the time they start, and end are different between infants and also maternal pregnancy.