In years past, once the calendar moved into September, there were straightforward recommendations across healthcare settings being provided to all adult patients about the benefits of receiving the annual influenza vaccine. Healthcare providers and patients are no longer in such a simple landscape for fall 2023. Along with the already-available influenza vaccines, two recently approved vaccines to prevent respiratory syncytial virus (RSV) are now available for older individuals, and the new updated COVID-19 boosters are expected to arrive toward the middle or end of September.
The Advisory Committee on Immunization Practices (ACIP) has clear guidance on influenza vaccines and those recommendations have not changed -- everyone is recommended to get a flu shot. ACIP has also released formal guidance around RSV vaccinations in adults 60 and older, but has yet to provide recommendations on use of one of the RSV vaccines, Abrysvo, which has also been approved for use in pregnant women to prevent RSV disease in infants. Guidance on who should receive the upcoming COVID-19 boosters, which will target an XBB strain, is not yet available from ACIP or CDC. Additionally, there are questions about timing of each of these vaccines, and whether they can be administered together or should be separated over time.
So, what are healthcare providers to do when trying to determine who will gain the most benefits from these three vaccines to prevent respiratory infections?
Flu Vaccines
Everyone 6 months of age and older should receive an influenza vaccine. Influenza vaccination not only prevents infection, it also significantly decreases the risk of severe disease, need for hospitalization, and death in those who are vaccinated and then get infected with influenza. People who are ages 65 and older should receive the high-dose influenza vaccine preparations. New this year, people with egg allergies can be vaccinated without special additional safety measures needed. They can receive any influenza vaccine (egg-based or non-egg-based) that is otherwise appropriate for their age.
It is not possible to predict when seasonal influenza will arrive, but it typically peaks in December-January. Getting vaccinated in September or October will still provide protection even if the flu season arrives in February or March.
RSV Vaccines
RSV may cause severe lower respiratory tract infections (LRTIs) in older adults and infants. Two RSV vaccines were approved by the FDA in May for the prevention of LRTIs in adults ages 60 and older. In June, the ACIP formally recommended that people ages 60 and above may receive a single dose of an RSV vaccine, using shared clinical decision-making. This means that the decision to proceed with RSV vaccination should be made between the patient and their healthcare provider after a discussion of the patient's underlying health conditions, their risk of severe RSV-associated LRTI, and the potential benefits, risks, and limitations of vaccination. Patients 60 and over with chronic lung diseases, asthma, congestive heart failure, coronary artery disease, diabetes, chronic kidney or liver diseases, and moderate or severe immunosuppression are among those most likely to benefit from RSV vaccination.
For eligible patients who decide they want to receive an RSV vaccine, the time to get vaccinated is now. Note that RSV vaccination should be offered without regard to seasonality to any unvaccinated adult who is in the target population (based on age and chronic conditions). With respect to severe side effects after an RSV vaccination, a small number of patients in the original vaccine trails did experience serious neurologic conditions including Guillain-Barré syndrome. However, these occurred rarely and it was not clear whether the vaccine caused the events. As part of any shared decision-making discussions, patients should be provided the CDC's RSV Vaccine Information Statement found here to help drive the conversation and decisions.
As noted above, one of the two approved RSV vaccines (Abrysvo, manufactured by Pfizer) was also approved in late August for use in women who are 32 to 36 weeks pregnant, as a tool to protect RSV in infants from birth to age 6 months. The vaccine was generally well tolerated with minimal side effects. There was a slightly increased incidence of preterm birth in the group who received the RSV vaccine, although a causal relationship has not been determined. The ACIP has yet to weigh in on guidance for use of the RSV vaccine in pregnancy, though it is under review and expected in the near future. When the time comes, this information should be provided to pregnant women considering RSV vaccination.
Updated COVID-19 Vaccines
The updated COVID-19 vaccines are expected in late September. They will target the XBB.1.5 strain of Omicron, which has circulated widely throughout the U.S. for much of 2023. These vaccines have not yet been evaluated by the FDA, and CDC and ACIP have not yet provided guidance. However, it is widely expected that once approved, the updated COVID-19 vaccines will be recommended for all adults 65 and older, for adults of any age with chronic medical conditions that make the risk of severe COVID more likely, for anyone with moderate or severe immunocompromising conditions, and for those who are pregnant.
The big questions will be focused on other populations such as healthy adults 50-65, adults under age 50 with chronic conditions, and teens and older children. Shared decision-making will probably be recommended for these groups. Patients who have had a recent COVID-19 infection should wait at least 3 months before getting a fall 2023-updated COVID vaccine. The same goes for patients who received a dose of the current bivalent vaccines any time since July 2023. Patients with severe immunocompromising conditions should discuss timing with their healthcare providers.
With COVID-19 rates on the rise nationally, there have been renewed questions about boosting those who are eligible now. Given that the updated COVID-19 vaccines are expected this month, most experts are advising patients to wait for the updated vaccine.
In terms of timing for getting vaccinated with the upcoming updated COVID-19 vaccines, individuals not in the higher risk groups may also want to consider when they want the highest level of protection, since we know that protective immunity begins to wane after about 2 to 3 months. For example, if someone is planning to spend the winter holidays traveling or with extended families in large indoor gatherings, then they may want to time their updated COVID-19 vaccine for late October or early November.
Timing and Co-Administration of Respiratory Virus Vaccines
Patients can receive an influenza vaccine simultaneously with either the RSV vaccine or the updated COVID-19 vaccines. Whenever multiple vaccines are administered at the same time, the injection sites should be spaced appropriately from one another, or in opposite arms. There are no data around co-administration of the RSV vaccines and COVID-19 vaccines. Most experts are recommending a 2-week period between receiving an RSV vaccine and the updated COVID-19 vaccine, but there are no data to guide these decisions, and patients should be encouraged to do what works best for them and their schedules. Some patients may be unable to make three separate trips to their provider's office or local pharmacy for the injections, and we don't want that to be a barrier to getting immunized. Although the landscape around fall vaccines is more complex this year, the overarching message healthcare providers should be sharing with their patients is how important these immunizations are to staying healthy during winter respiratory virus season.
Judith A. O'Donnell, MD, is chief of infectious diseases, director of infection prevention, and hospital epidemiologist at Penn Presbyterian Medical Center. She is also professor of clinical medicine at the University of Pennsylvania Perelman School of Medicine in Philadelphia.