IDSA updates flu and RSV vaccine guidelines, urging extra caution for immunocompromised patients

The Infectious Diseases Society of America updated its flu and respiratory syncytial virus (RSV) vaccine guidelines today, noting that live-attenuated flu vaccines should not be used in immunocompromised patients and should be avoided by those in close contact with those who are severely immunosuppressed.

These updates are part of a rapid guideline effort the society launched on October 17, when it first released recommendations focused solely on COVID-19 vaccination for the 2025 to 2026 respiratory infection season. The society expanded the guidelines on November 4 to include flu and RSV vaccines for adults and children who are immunocompromised, reflecting the growing need for clear, evidence-based direction as respiratory viruses circulate.

Immunocompromised folks, including patients with hematologic cancers, primary immunodeficiencies, HIV with severe immunosuppression, or those receiving organ transplants, stem cell transplants, CAR-T therapy, or chemotherapy, face higher risks from these infections and depend heavily on well-timed and appropriate vaccinations.

Today’s update gives more specific guidance on live-attenuated flu vaccines and urges extra caution for households with someone who is severely immunosuppressed.

“We are in the midst of respiratory virus season, and vaccines are an effective tool to protect people with compromised immunity,” Lindsey Robert Baden, M.D., vice president of clinical research at Mass General Brigham, and chair of IDSA’s guideline panel, said in a press release. “IDSA’s guidelines for vaccination protect people who are often undergoing treatment for serious health conditions against preventable illness.”

The IDSA guideline was developed by a panel of experts—like Baden—in infectious diseases, oncology, transplantation, immunology, pediatrics and HIV. The group focused on one main question for each vaccine: whether it should be used in immunocompromised patients. They then identified key outcomes such as hospitalization, death, severe illness and serious side effects.

The panel reviewed evidence published between 2023 and mid-2025, using a systematic review from the Vaccine Integrity Project and additional searches. They applied the GRADE (grading of recommendations assessment, development and evaluation) framework to judge the quality of the evidence and the strength of each recommendation, using pooled vaccine effectiveness data and assessing study bias with standard tools.

For COVID-19, the panel advised administering an FDA-approved vaccine as soon as possible, with a second dose likely to extend protection, and encouraged household members to stay up to date.

Vaccine effectiveness in immunocompromised patients has been shown to reduce hospitalizations, critical illness and death, with few serious outcomes reported, according to authors.

Flu vaccination is recommended every year, and high-dose or adjuvanted vaccines give stronger immune responses for those with weakened immune systems. The guidelines note that live-attenuated flu vaccines such as FluMist should not be given to immunocompromised patients and should be avoided in households with people who are severely immunosuppressed.

RSV vaccination is recommended for adults and adolescents. It was noted that solid organ transplant candidates should ideally be vaccinated before a transplant.

For children under 18 years, vaccination should be guided by shared decision-making. It’s safe to give COVID-19, flu and RSV vaccines at the same time, though timing should be considered when under immunosuppressive therapy, a transplant, chemotherapy and biologics.

The panel also stressed the importance of reducing risk through antivirals, other preventive measures and quick access to treatment. In addition, vaccination plans should be personalized with shared decision-making, close coordination with doctors and attention to household vaccination. Research is still needed on immune responses, best dosing schedules, long-term effectiveness and rare side effects.

These guidelines offer clear strategies to protect immunocompromised patients from serious illness while helping doctors and patients make informed vaccination decisions.