A new analysis of data from the long-term COVID-19 influenza vaccine trial indicates that people with weakened immune systems may be more susceptible to a potentially serious complication of flu vaccination than had been known.
The study, which is to be published in the International Journal of Infectious Diseases, found that one booster dose of COVID-19 was needed in individual patients to prevent a prolonged illness. However, some patients with highly immunocompromised immune systems who were initially not protected by COVID-19 may need a fourth booster dose.
“As this meta-analysis confirms, these patients are at risk for serious complications from this vaccine,” says the research team led by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, in a statement.
The COVID-19 vaccine has been reported to be effective against the flu for more than ten years, yet the vaccine has not been recommended in all U.S. flu clinics, according to the statement. This is particularly true of people who are considered high-risk.
Lack of face masks and regular influenza-prevention efforts may not be sufficient to protect patients with compromised immune systems, the study authors say.
Coordinators of the highly protected COVID-19 group say that they and other researchers continue to study whether COVID-19 can be used in patients who were not originally adequately protected by the vaccine.
But the authors note that according to NIAID’s positive phase III trial, the current protocol for future trials of COVID-19 may need to be modified to protect even more patients with weakened immune systems. This could include limiting the use of dose-specific vaccines and modifying the use of “herd immunity” to improve effectiveness.