Nurse Roy Christian receives the Covid-19 vaccine at John Sealy Hospital at the University of Texas Medical Branch in Galveston, Texas on December 15, 2020.Coronavirus variants threaten to upend pandemic progress. Here's how 4 top vaccine makers are fighting back.
The emergence of coronavirus variants threatens to lower the efficacy of COVID-19 vaccines and extend the pandemic's trajectory. A barrage of data released in January showed a variant widely circulating in South Africa is particularly troubling.