Presence of antibodies in nasal mucosa suggest vaccine-induced immune protection at source of infection
IgA antibodies against RSV observed in both serum and mucosa of vaccinated individuals
Bavarian Nordic A/S (OMX: BAVA, OTC: BVNRY) today announced additional positive data from its 421 patient, Phase 2 study investigating the safety and immune effects of its universal RSV vaccine, MVA-BN RSV in an older adult population.
In a planned follow-up analysis, nasal swabs demonstrated, on average, an approximately 1.5-fold increase in IgA antibodies over baseline levels, with peak increases seen in the weeks immediately following vaccination. The boosting effect was more pronounced in individuals with a lower baseline mucosal IgA at the time of vaccination. This observation suggests that the vaccine has the desired effect of boosting memory responses against RSV in patients with a poor underlying immunity.
Previous published studies have shown that in RSV human challenge studies, the presence of IgA antibodies in the mucosa is highly correlated with immune protection in subjects who do not develop symptoms of RSV. In those studies, the level of IgA expression seen was similar to the levels of expression detected post-vaccination with MVA-BN RSV.
“The presence of mucosal IgA in vaccinated subjects is a truly encouraging, demonstrating that our vaccine is performing as intended. The ability to fight off a severe RSV infection wanes as individuals get older. Observing a booster effect in this elderly population gives us additional confidence that protection against RSV may be possible in this at-risk population using our vaccine. With a mortality rate on par with influenza, the need for an RSV vaccine remains significant,” said Paul Chaplin, President and CEO of Bavarian Nordic.
MVA-BN RSV has been specifically designed to mimic a natural RSV infection, and can boost the body’s memory response against RSV. The vaccine has been shown to elicit T-cells and humoral antibodies against each of the 5 targets encoded in the vaccine, as well as the whole virus. Previously reported data demonstrated that the vaccine induced sustained protection levels for up to 6 months, the duration of an RSV season, against all 5 encoded targets when compared to a placebo.