COMMENTARY

New Mid-Year Vaccine Recommendations From ACIP

Sandra Adamson Fryhofer, MD

DISCLOSURES

This transcript has been edited for clarity. 

ACIP, the CDC's Advisory Committee on Immunization Practices, met for 3 days in June. New vaccines and new recommendations for respiratory syncytial virus (RSV), flu, COVID, and a new pneumococcal vaccine were revealed. 

RSV Protection

We'll begin with RSV vaccines for adults aged 60 or older. For this group, shared clinical decision-making is out; it no longer applies. New, more specific recommendations from ACIP for RSV vaccines are both age based and risk based. The age-based recommendation applies to those aged 75 or older, who should receive a single RSV vaccine dose. If they have already received a dose under the old recommendation, they don't need another one, at least for now. 

The risk-based recommendation applies to adults from age 60 up to 75, but only for those with risk factors for severe RSV. These risk factors include lung disease, heart disease, immunocompromise, diabetes, obesity with a BMI of 40 or more, neurologic conditions, neuromuscular conditions, chronic kidney disease, liver disorders, hematologic disorders, frailty, and living in a nursing home or other long-term care facility. Those aged 60-75 with these risk factors should receive the RSV vaccine, and those without them should not receive it. The best time to get the RSV vaccine is late summer, but early fall administration with other adult vaccines is allowed and is acceptable. 

Vaccine safety concerns were top of mind as ACIP members began their deliberations. Possible safety concerns for RSV vaccines have been detected for Guillain-Barré syndrome, atrial fibrillation, and idiopathic thrombocytopenic purpura. Safety surveillance updates are still interim and inconclusive. These signals still need further study and clarification. 

Two RSV vaccines have been on the market: one by Pfizer, called Abrysvo, which does not contain an adjuvant; and another one by GSK, called Arexvy, which does contain an adjuvant. With the recent FDA approval of Moderna's new mRNA RSV vaccine, mRESVIA, there are now three RSV vaccines licensed for those 60 or older. Arexvy is now FDA approved for adults in their 50s. That just happened in early June, but ACIP doesn't currently recommend it for this fiftysomething age group, even for those at high risk for severe RSV disease. This may change with greater clarification of potential vaccine safety concerns. 

There is also news about protecting babies from RSV. RSV is the most common cause of hospitalization for infants in the United States, and most hospitalizations for RSV are in healthy, full-term infants. We now have two ways to protect babies: a dose of RSV vaccine given to mom, or a dose of the long-acting monoclonal antibody nirsevimab given to the baby. ACIP clarified that those who received a dose of maternal RSV vaccine during a previous pregnancy are not recommended to receive additional doses during future pregnancies, but infants born to those who were vaccinated for RSV during a prior pregnancy can receive nirsevimab, which is recommended for infants up to 8 months of age during their first RSV season, and for high-risk infants and toddlers aged 8-19 months during their second RSV season. 

Last RSV season, supplies of nirsevimab were limited and doses had to be prioritized. No supply problems are anticipated for the upcoming season. A study published in March showed that nirsevimab was 90% effective at preventing RSV-associated hospitalization for infants in their first RSV season. 

COVID

Here's what's new for COVID vaccines. A new-formula COVID vaccine will be ready for fall. ACIP voted unanimously to recommend a dose of the updated 2024-2025 COVID vaccine for everyone aged 6 months or older. This is a universal recommendation, just like the one we have for flu. But understand that even though COVID has waned, it's still more deadly than flu. Most Americans now have some immunity against COVID, but this immunity wanes with time, and it also wanes as the virus keeps changing. These updated vaccines provide an incremental boost to our immunity for the new formula for fall. FDA has directed manufacturers to use a monovalent JN.1 lineage formula, with a preference for the KP.2 strain. 

Older adults (aged 75 or older) and children under 6 months old are hit hardest by COVID. The littlest ones are too young to be vaccinated, but they can get protection from maternal vaccination. The uptake for last year's COVID vaccine has been disappointing. Only 22.5% of adults and 14% of children received a dose of the updated shot. Focus-group discussions highlight the importance of a physician recommendation. Adults and children who receive a healthcare provider's recommendation to get the COVID vaccine are more likely to get vaccinated. 

Pneumococcal Vaccines

On June 17, 2024, a new pneumococcal vaccine, PCV21, was FDA approved for those aged 18 or older under an accelerated-approval pathway. ACIP voted to keep it simple and recommends PCV21 as an option for adults aged 19 or older who currently have an indication to receive a dose of PCV. This new PCV21 vaccine is indicated for prevention of both invasive pneumococcal disease (IPD) and pneumococcal pneumonia. Its brand name is Capvaxive and it's made by Merck. IPD includes bacteremia, pneumonia, pneumococcal bacteremia, and meningitis.

There are two basic types of pneumococcal vaccines: polysaccharide vaccines (PPSV), which do not produce memory B cells; and PCV conjugate vaccines, which do trigger memory B-cell production and therefore induce greater long-term immunity. PCV21 covers 11 unique serotypes not in PCV20. This is important because many cases of adult disease are caused by subtypes not covered by other FDA-approved pneumococcal vaccines. PCV21 has greater coverage of the serotypes that cause invasive disease in adults as compared with PCV20. PCV20 covers up to 58% of those strains, while PCV21 covers up to 84% of strains responsible for invasive disease in adults. But there's one serotype missing in PCV21, which may limit the groups who receive it. PCV21 does not cover serotype 4, a major cause of IPD in certain populations. Adults experiencing homelessness are 100-300 times more likely to develop IPD due to serotype 4. So are adults in Alaska, especially Alaska Natives. They have an 88-fold increase in serotype 4 invasive disease. Serotype 4 is covered by other pneumococcal vaccines, so for these patients, PCV20 is likely a better high-valent conjugate vaccine option than PCV21. 

Flu Vaccines

What's new for flu? Everyone aged 6 months or older needs a seasonal flu vaccination every year. That's not new, but there are two new things coming this fall: (1)The seasonal flu vaccine is going trivalent. FDA has removed the Yamagata flu B strain because it no longer appears to be circulating. (2) ACIP made a special off-label recommendation to boost flu protection for solid organ transplant recipients age 18 through 64 who are on immunosuppressive medications. These high-risk patients now have the off-label option of receiving one of the higher-dose flu vaccines, including high-dose and adjuvanted flu vaccines, which are FDA approved only for those 65 or older.

 

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