HALF Americans Might Have Some Protection Against COVID-19: Studies Show Many People Have Immune T cells to Other Coronaviruses Responding to New Virus
- A study of donated blood in the US found that half of the samples had immune T cells that responded to SARS-CoV-2
- Likewise, high rates were found in smaller studies of human blood in the UK, Singapore, Germany and the Netherlands
- T cells engineered to fight other coronaviruses may be ‘cross-reactive’ with the new virus that causes COVID-19
As many as half of the world’s population may be somewhat immune to the coronavirus, a small but growing body of research suggests.
Tests of donated blood in the US found that about 50 percent of the samples had immune T cells that responded to the coronavirus, suggesting that the donors’ bodies have the natural ability to fight the deadly virus.
Similar results have been found in the UK and Sweden.
COVID-19 is thought to be so deadly in part because it is an entirely new virus against which humans have no natural immunity.
And while that is clearly the case for many people, British Medical Journal associate editor Dr. Peter Dosh wrote on Thursday that the evidence is beginning to suggest that some people may have some protection against the virus.
Some people have immune T cells to other coronaviruses that can fight SARS-CoV-2, recent research suggests
In March, a member of a choir in Skagit County, Washington, went to their usual practice, feeling a little ill, but unaware they had coronavirus.
Within a week, that person and another had tested positive for the virus that causes COVID-19. Another 25 members of the 122-piece choir had symptoms of coronavirus.
In the weeks that followed, 52 of the 60 other participants in the practice developed COVID-19.
The choral practice was called a superspreader event and became an early indicator that certain activities, such as singing, could facilitate the transmission of coronavirus.
Scientists saw the practice as a unique opportunity to investigate how contagious coronavirus can be.
But less controversial were the eight attendees who did not become ill, or why.
Research has shown that people are more likely to contract the coronavirus and become seriously ill from it if they are repeatedly exposed, but this group shared a distinctly common exposure.
An unexplored explanation could be that some people already have immunity to the coronavirus.
Most research on coronavirus immunity has focused on antibodies, immune cells that develop after the body is exposed to a new pathogen. They are tailor-made to fight that specific virus or bacteria.
In badly affected cities, such as New York, the percentage of people with antibodies that could protect them from reinfection is still quite low. In New York City, about 23 percent of people tested for antibodies have these.
Now scientists are beginning to look more closely at T cells, which, like antibodies, are part of the adaptive immune system and learn to identify and fight specific pathogens.
In addition to the US study, two out of ten people had T cells in their blood that responded to SARS-CoV-2 in the Netherlands, as well as about a third of the samples tested in Germany and most of those in Singapore.
They are all small studies but point in the same direction.
Although SARS-CoV-2 itself is new, it belongs to a family of many related coronaviruses.
Scientists think some people may have developed T cells for other coronaviruses that are “cross-reactive” with SARS-CoV-2 because they are sufficiently similar.
If so, the world may be closer to herd immunity to the deadly infection than we think, but there is still a lot of research to be done before we can know if that’s the case.