Universal Flu Vaccine Candidate Shows Protection in New Trial

The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), has shared promising results from an efficacy trial investigating an experimental universal flu vaccine.

The experimental vaccine, FLU-v, decreased the chance that participants would develop flu symptoms and viral shedding.

The trial was conducted by administering either a placebo injection or 1 or 2 doses of the experimental vaccine to healthy volunteers. Volunteers were then exposed to a seasonal influenza strain under controlled conditions.

Traditional flu vaccines only work against the strains in seasonal circulation. They also tend to have moderate effectiveness, though they also seem to reduce the severity of flu if a person becomes infected.

FLU-v is a universal flu vaccine candidate that is designed to provide long-lasting protection against most or all strains of influenza.

While traditional flu vaccines work via antibodies, FLU-v works through stimulating cellular immunity.

“Cellular immune responses include activity by white blood cells called cytotoxic T lymphocytes (CTLs). Recent research has shown that influenza-specific CTLs can seek out and remove virus-infected cells before and after flu symptoms arise,” according to the NIAID press release.

FLU-v catalyzes production of these CTLs by targeting proteins inside the virus that do not vary substantially from strain to strain.

In the trial, volunteers were randomly assigned to 1 of 3 blinded groups. The first group received 2 doses of FLU-v, the second received 1 dose of FLU-v followed by a saline placebo, and the third group received 2 placebo injections.

Either 22 or 43 days after the second injection, all volunteers were exposed to live influenza virus via a nasal spray.

The volunteers who received 1 to 2 doses of FLU-v were significantly less likely to develop mild to moderate influenza than volunteers who received both placebo doses.

In the placebo group, 23 of 42 volunteers (54.8%) experienced viral shedding and clinical influenza symptoms.

In the 2 dose group, 15 of 41 volunteers (36.6%) developed influenza. In the 1 dose group, 13 of 40 volunteers (32.5%) developed influenza.

“…cellular immunity may be a very important and necessary component of future broadly protective universal influenza vaccines,” Matthew J. Memoli, MD, lead investigator of the study said in the statement.

While current seasonal influenza vaccines aren’t perfect, there is still a sizable personal and public health advantage to vaccination. But perhaps a universal flu vaccine is now a step closer to reality.