Initial evidence that the Oxford/AstraZeneca vaccine offered only “minimal” protection against mild to moderate cases of the Covid-19 variant first identified in South Africa has focused global attention on the threat posed by mutations.
Variants have become increasingly prevalent as the Sars-Cov-2 virus has spread around the world infecting more than 100m people. Some of the mutations have made the virus more contagious and better able to escape the immune protection provided by vaccines and prior infection.
The South African study was relatively small and did not assess the effect of vaccination on severe disease or mortality, but the results have already persuaded its government to halt the roll-out of the Oxford/AstraZeneca shot.
您已閱讀13%（741字），剩余87%（4803字）包含更多重要信息，訂閱以繼續(xù)探索完整內(nèi)容，并享受更多專屬服務。