A fourth coronavirus vaccine is making its way to the United States. Health experts say the vaccine, Covavax, is the most effective to date showing protection against the original COVID-19 strain, but also against variants of concern. Covavax is the Indian brand name for Novavax, the American Company that developed the vaccine.Researchers from 113 sites across the country assessed 29,000 infected patients. Results of the study showed it was 100% effective against the original SARs-CoV-2 and 93% against the alpha and delta strains, both of which are on the World Health Organization’s list of variants of concern. But what’s so...