New COVID-19 vaccine authorized; reviews analyze myocarditis, drug treatments

The Novavax COVID-19 vaccine received an emergency use authorization from the FDA on July 13. The adjuvanted vaccine is administered as two doses three weeks apart and is authorized for patients 18 years of age and older. Authorization was based on a placebo-controlled study conducted in the U.S. and Mexico before the emergence of the delta and omicron variants. It found that the vaccine was 90.4% effective in preventing mild, moderate, or severe COVID-19 in the overall study population and 78.6% effective in those 65 years of age and older. The most commonly reported side effects included pain/tenderness, redness and swelling at the injection site, fatigue, muscle pain, headache, joint pain, nausea/vomiting, and fever.

A new review looked at the risk of myocarditis or pericarditis after vaccination with either of the mRNA COVID-19 vaccines. The living evidence synthesis, published by The BMJ on July 13, included 46 studies and found that incidence of myocarditis after vaccination was highest in teenage and young men (50 to 139 cases per million [low certainty] in those ages 12 to 17 years and 28 to 147 per million [moderate certainty] in those ages 18 to 29 years). Fewer than 20 cases per million were found in girls and boys ages 5 to 11 years and women ages 18 to 29 years. With moderate certainty, the review found higher incidence of myocarditis with the Moderna vaccine than the Pfizer-BioNTech vaccine. Low-certainty evidence supported reduced risk of myocarditis with a dosing interval of more than 30 days, but data specific to men ages 18 to 29 years indicated that the dosing interval might need to increase to 56 days or more to substantially drop myocarditis or pericarditis incidence. “A clinical course of mRNA related myocarditis appeared to be benign, although longer term follow-up data were limited,” the authors observed.

Another living systematic review related to COVID-19 was updated and published by The BMJ on July 13. This latest analysis of drugs for COVID-19 included 463 treatment trials with 166,581 patients, slightly more than half of whom were not included in the last update. The new review found (with moderate certainty) that three drug classes reduced COVID-19 mortality, mostly in patients with severe disease: systemic corticosteroids, interleukin-6 receptor antagonists when given with corticosteroids, and Janus kinase inhibitors. Nirmatrelvir/ritonavir and molnupiravir probably reduce risk of hospital admission compared to standard care, and remdesivir may reduce hospitalization risk, the review showed. Only molnupiravir had moderate-quality evidence supporting a reduction in time to symptom resolution, but other drugs showed a possible benefit for that outcome. Several drugs were tied to increased adverse effects, including hydroxychloroquine, which probably increased the risk of mechanical ventilation.