1/ Basics (for non-immunologists) of important new results in COVID-19 immunity. The new finding helps explain how our immune system responds to COVID-19, perhaps why men are more prone to severe COVID-19, and may help make future vaccines more effective. https://jamanetwork.com/journals/jama/fullarticle/2768926

2/ Researchers in the Netherlands studied two families that each had two brothers who developed severe COVID-19 at a young age. Since this usually happens in older people, they wanted to understand whether these patients had something wrong with their immune response...

3/ ...that led to them having severe disease. They found, when they sequenced their genome, that they shared a rare mutation in the innate immune system that specifically targets the COVID-19 type of virus...

4/ The innate immune system isn’t the specific one that focuses on T cells and B cells, but produces a more primitive and general immunity. Receptors in the innate immune system can target specific kinds of viruses...

5/ ..and this mutation eliminates the response to the very type of virus that COVID-19 is. This finding is strong evidence that the normal TLR7 gene plays an important role in preventing COVID-19 patients from developing severe respiratory disease...

6/ Since it is a rare mutation, it probably isn’t the cause of severe COVID-19 in many people. However, it can tell us something about how the normal version of the TLR7 gene works, and what that means. And...

7/ The gene is located on the X chromosome, and women have two copies of the X chromosome while men only have one. So, the authors of this study wonder whether this difference could explain why men are more prone to severe COVID-19.

8 and end/ Finally, some have suggested that boosting TLR7 function might be helpful in producing vaccines to human diseases where TLR7 plays a role. COVID-19 might be the perfect candidate.

For more technical aspects and links to papers see: https://twitter.com/pbleic/status/1287002569324150785