A new study by Weill Cornell Medicine-Qatar researchers reveals how the SARS-CoV-2 virus evolved from prioritizing increased transmissibility to enhanced immune evasion after the Omicron variant emerged. The study, published in Nature, analyzed over 1.5 million people and found that natural immunity gained from a previous infection provided robust protection against reinfection before Omicron, with an estimated effectiveness of around 80%. However, after Omicron became dominant, immune protection declined rapidly to negligible levels within a year.
The study suggests that the emergence of Omicron marked a turning point in the pandemic. The virus evolved by genetic mutations that increased its ability to spread from person to person before Omicron, but after the variant emerged, it developed mechanisms to escape the immune system. This led to highly genetically diverse subvariants of Omicron.
The researchers emphasize that the virus will continue to reinfect people and highlights the importance of regular vaccine updates in renewing immunity and protecting vulnerable populations. While the virus has shown remarkable adaptability, it will no longer pose the same severe threat as it did when it first emerged.
Source: https://news.weill.cornell.edu/news/2025/02/how-sars-cov-2-evolved-through-the-covid-pandemic