A laboratory-developed pseudovirus containing the mutations found in the SARS-CoV-2 501Y.V2 variant (first detected in South Africa) was resistant to neutralization when exposed to three types of COVID-19 therapeutic antibodies or convalescent plasma, according to a paper published in Nature Medicine. These findings raise the possibility of reinfection and suggest that vaccines that target the SARS-CoV-2 spike may not be as effective against emerging variants of the virus.