Note: Happy July 4th weekend (almost)!  Q&A will be on pause until July 6th.

Question: Got any good news?

Answer: Yes!  Yesterday, New England Journal of Medicine published two studies with promising results showing that: a) Novavax vaccine has high efficacy, including against the Alpha variant; and b) mRNA vaccines (Pfizer, Moderna) are highly effective in real-life conditions, and even the very few study participants who experienced breakthrough infections were well protected from severe disease.

1. Safety and Efficacy of NVX-CoV2373 Covid-19 Vaccine: Results from a phase 3 randomized control trial of Novavax safety and efficacy among ~15K adult trial participants in the UK show that the vaccine has 100% efficacy at preventing severe disease.  Novavax has”86.3% (95% CI, 71.3 to 93.5) against the B.1.1.7 (or alpha) variant and 96.4% (95% CI, 73.8 to 99.5) against non-B.1.1.7 variants.”  Most common reported side effects among vaccinated participants were pain at the injection site, headache, muscle pain, and fatigue (Figure 1).  
2. Prevention and Attenuation of Covid-19 with the BNT162b2 and mRNA-1273 Vaccines: This prospective cohort study followed ~4,000 health care professionals working in high COVID exposure risk settings between December 2020 and April 2021.  Participants completed weekly testing.  Over the course of the study, 204 participants (5%) became infected, of whom 5 were fully vaccinated, 11 partially vaccinated, and 156 unvaccinated. “Adjusted vaccine effectiveness was 91% (95% confidence interval [CI], 76 to 97) with full vaccination and 81% (95% CI, 64 to 90) with partial vaccination.”  Among the participants who became infected, mean viral load was 40% lower among participants who were at least partially vaccinated.  Additionally, “only 25% of those who were partially or fully vaccinated reported febrile symptoms, as compared with 63% of those who were unvaccinated; the risk of febrile symptoms was 58% lower with at least partial vaccination. Vaccinated participants also reported 6.4 fewer total days of symptoms (95% CI, 0.4 to 12.3) and 2.3 fewer days spent sick in bed with Covid-19 (95% CI, 0.8 to 3.7) than unvaccinated participants.”  

Figure 1. Reported Side Effects (Novavax and Placebo) After 1st and 2nd Doses (from NEJM)