Older adults can receive respiratory syncytial virus (RSV) and COVID-19 vaccines at the same appointment without reducing their effectiveness, according to a new clinical trial published in Clinical Infectious Diseases. The finding could simplify vaccination schedules and help more people stay protected against two serious respiratory viruses that pose particular risks to people aged 50 and older.

Why Do Older Adults Need Both Vaccines?

Both RSV and COVID-19 can cause severe illness in older adults and people with chronic health conditions. RSV, a virus many people catch in childhood, can cause serious pneumonia and other complications later in life. Because vaccination against both pathogens is often recommended for similar populations, researchers wanted to know whether getting them on the same day would affect how well they work.

The study included 833 participants aged 50 and older, with a mean age of approximately 64 years. About 92% of participants had at least one chronic medical condition, such as metabolic disorders, vascular disease, or musculoskeletal problems. Researchers randomly assigned participants to receive both vaccines during the same visit or approximately one month apart, then tracked their immune responses and any side effects for up to six months.

What Did the Study Find About Immune Response?

The results were reassuring. When participants received both vaccines together, their bodies produced strong antibody responses against both RSV subtypes (RSV-A and RSV-B) that were comparable to those who received the vaccines separately. For RSV-A, antibody levels increased more than eightfold from baseline, and for RSV-B, they increased nearly sevenfold in both groups.

For COVID-19 protection, antibody levels also increased more than fourfold in both groups. While one measure of COVID-19 immune response narrowly missed the study's prespecified threshold, a sensitivity analysis in the larger population confirmed that giving both vaccines together did not meaningfully reduce COVID-19 protection.

Were There More Side Effects When Getting Both Vaccines?

Participants who received both vaccines during the same visit reported more side effects than those who received them separately, but the reactions remained mild to moderate and resolved within a few days. The most common local reaction was injection-site pain, while muscle aches and fatigue were the most frequent systemic side effects.

Serious adverse events were rare in both groups. Within 30 days after vaccination, unsolicited side effects occurred in about 21% of people who received both vaccines and 26% of those who received them separately. Severe side effects through six months occurred in fewer than 4% of participants in either group, and no deaths were reported during the study.

How to Prepare for a Dual Vaccination Appointment

• Schedule in advance: Contact your healthcare provider to arrange an appointment where both RSV and COVID-19 vaccines are available, ensuring you don't need to make multiple trips.
• Plan for mild side effects: Expect possible injection-site soreness, muscle aches, or fatigue that typically resolve within a few days; over-the-counter pain relievers can help manage discomfort.
• Stay hydrated and rest: Drink plenty of water and allow yourself time to rest after vaccination, as fatigue is a common but temporary reaction.
• Bring your vaccination record: Have documentation of any previous COVID-19 vaccines so your provider can ensure you receive the most appropriate updated formulation.

The researchers concluded that "co-administration of the vaccines may streamline vaccination efforts and support higher vaccine uptake." This is particularly important because many older adults struggle to keep up with multiple vaccination appointments, and simplifying the process could help more people get the protection they need.

What About Different COVID-19 Vaccine Options?

While the RSV and COVID-19 co-vaccination study focused on one vaccine combination, recent real-world data also sheds light on which COVID-19 vaccines may offer the strongest protection. Among insured adults in the United States during the 2024 to 2025 respiratory virus season, those who received the mRNA-1273 vaccine (Moderna's updated formulation) experienced a 31.7% lower risk for medically-attended COVID-19 compared with recipients of the protein-based NVX-CoV2705 vaccine (Novavax's formulation).

The difference was even more pronounced for hospitalization. Adults who received mRNA-1273 had a 40.7% lower risk for COVID-19-related hospitalization compared with those who received NVX-CoV2705. Among adults aged 65 and older specifically, mRNA-1273 was associated with a 25.7% lower risk for medically-attended COVID-19 and a 41.7% lower risk for hospitalization.

The study included nearly 70,000 mRNA-1273 recipients and about 34,500 NVX-CoV2705 recipients, with a mean age of 66 years and approximately 75% having at least one high-risk condition for severe COVID-19. Protection from both vaccines remained consistent throughout the approximately six-month follow-up period.

What's the Bottom Line for Older Adults?

The evidence supports getting both RSV and COVID-19 vaccines, and doing so at the same appointment is both safe and effective. The convenience of a single visit may encourage more older adults to stay current with these important protections. When choosing a COVID-19 vaccine, discuss with your healthcare provider which formulation may be best for your individual health situation, as real-world data suggests some differences in effectiveness between available options.

Study limitations include the lack of immunocompromised individuals in the RSV and COVID-19 trial, enrollment primarily from high-income countries, and reduced racial diversity among participants. The researchers noted that cellular immune responses, which are another important part of immunity, were not evaluated in the study.