Understanding how some people naturally resist Covid infection, despite clearly being exposed to the virus, could lead to better vaccines, say researchers.  A team at University College London said some people had a degree of Covid-immunity before the pandemic started. Upgrading vaccines to copy this protection, could make the jabs even more effective, the team said.

The scientists were closely monitoring hospital staff during the first wave of the pandemic - including by taking regular blood samples. The results, published in the journal Nature, showed some people just managed to avoid the virus.  But around one-in-10 had signs of being exposed, but never had symptoms, never tested positive and never developed Covid-fighting antibodies in their blood. Part of their immune system was able to get on top of the virus before it managed to take hold - what’s known as an “abortive infection”.
Source : BBC