8. Is there evidence that Covid can mess up people’s immune system so that it doesn’t work properly, over and above the fact that all types of viral infections can lead to bacterial infections in some people?

Yes, there is. For example, a 6-months long study of immune responses identified in the blood of 69 people, most of them suffering from Long Covid, showed significant falling away of immune responses throughout that period. These changes were most marked in those with Long Covid. 

The US-based Autoimmunity Registry has included Long Covid on its list of autoimmune diseases based on “biomarkers of immune system activity”. 

But in addition significant negative changes to people’s immune system following Covid infection, at least temporarily, have also been found in blood taken from people who did not consider themselves to have Long Covid. 

Frequent, including recurrent infections, worse than usual symptoms from a common cold virus, and secondary bacterial infections, are typical signs of an immune system that is not functioning as it should. This makes it all the more important to pay attention to the anecdotal evidence of families reporting “almost constant colds” discussed under Question 3.