How some people naturally resist Covid infection, despite clearly being exposed to the virus? Understanding this could lead to better vaccines, BBC reports.

A degree of Covid-immunity before the pandemic started
 

A team at University College London said some people had a degree of Covid-immunity before the pandemic started. This likely came from the body learning how to fight viruses that are related to the one which has swept the world.

The British researchers said that they have identified proteins in the coronavirus that are recognised by T-cells of people who are exposed to the virus but resist infection, possibly providing a new target for vaccine developers.

They found that, while a subset of the workers did not generate antibodies or test positive with PCR tests, they had still generated a large and broad T-cell response following possible exposure.

To spot a different part of the virus
 

These T-cells were able to spot a different part of the virus ...