Universal Influenza Vaccine Targeting Hemagglutinin Stalk Shows Early Promise

A new vaccine that targets the evolutionarily conserved hemagglutinin 1 (H1) stalk instead of the commonly targeted head protein has shown promising results in a phase 1 clinical trial. Interim results show that the cross-reactive antibodies are produced in response to vaccination

The study used 3 different treatment groups: one containing an unadjuvanted H8/1 live attenuated vaccine followed by unadjuvanted H5/1 inactivated vaccine, another with unadjuvanted H8/1 followed by H5/1 adjuvanted with AS03, and a third with both H8/1 and H5/1 adjuvanted with AS03. The study also had 2 placebo groups, one receiving phosphate-buffered saline placebo and another receiving sterile saline, but the group did not report results of the sterile saline group due to low starting numbers and high dropout. All participants had pre-existing anti-stalk antibody titres. An initial vaccine or placebo was given on day 1 of the study and a booster shot was given at day 85

After the first vaccination, the third (double adjuvant) treatment group showed a significant increase in H1 anti-stalk titres, with 80% achieving 4-fold higher titre levels. Similarly, patients in this group exhibited 8.9 fold increases in H2 anti-stalk titres, demonstrating cross reactivity between different families of hemagglutinin stalks. The other two treatment groups exhibited no increase in titres after the initial vaccination, but a 5.8 fold increase after the booster vaccination in the single adjuvant group, and a 2.2 increase in the non-adjuvanted group over baseline. No increases were seen in the placebo group.

Jacob Thoenen

Sources:
1. Hemagglutinin-Based Universal Flu Vaccine Shows Early Promise
2. Immunogenicity of chimeric haemagglutinin-based, universal influenza virus vaccine candidates: interim results of a randomised, placebo-controlled, phase 1 clinical trial