Scientists remain concerned about virus variants, some of which have mutations that limit but do not completely block the protective effects of vaccines. On May 1 the CDC halted its effort to monitor post-vaccination “breakthrough infections” that do not results in hospitalization or death. Continuing to show the public the rarity of breakthrough cases will buttress faith in the vaccines, she said. Monitoring the impact of breakthrough cases among school staff also will be important, she said. “The breakthrough infection number is not particularly relevant as long as they don’t spread the infection to anybody else,” he said.
