COVID shots still work but researchers hunt new improvements

COVID-19 vaccinations are at a critical juncture as companies test whether new approaches like combination shots or nasal drops can keep up with a mutating coronavirus—even though it's not clear if changes are needed.
COVID-19 vaccinations are at a critical juncture as companies test whether new approaches like combination shots or nasal drops can keep up with a mutating coronavirus—even though it’s not clear if changes are needed.