New%20SARS-CoV-2%20Variants%20%u2014%20Clinical%2C%20Public%20Health%2C%20and%20Vaccine%20Implications%20%7C%20NEJM

New%20SARS-CoV-2%20Variants%20%u2014%20Clinical%2C%20Public%20Health%2C%20and%20Vaccine%20Implications%20%7C%20NEJM The clinical relevance of the lower neutralization activity for either mild or severe Covid-19 is not clear, but efficacy in clinical trials was lower for all three vaccines tested in the midst of transmission of the 501Y.V2 variant in South Africa than efficacy in trials conducted in countries with preexisting variants. Efficacy was higher by a factor of 3.2 with the AZD1222 vaccine in the United Kingdom and Brazil than in South Africa (70% vs. 22%), higher by a factor of 1.8 with the NVX-CoV237 vaccine in the United Kingdom than in South Africa (89% vs. 49%), and higher by a factor of 1.3 with the Ad26.COV2.S vaccine in the United States than in South Africa (72% vs. 57%).