...now read the linked NEJM study in the paragraph after the India piece:
A national database study including almost 22,000 people in Qatar published in the New England Journal of Medicine showed that previous infection was "robust" - approximately 90% - in preventing reinfection with the Alpha, Beta, and Delta variants of SARS-CoV-2, and approximately 60% "but still considerable" against Omicron. None of the re-infections progressed to critical or fatal outcomes and the effectiveness against severe, critical, or fatal COVID-19 was estimated to be 69.4% against Alpha, 88.0% against Beta, 100% against Delta, and 87.8% against Omicron variants.
