After testing donated blood in the US, it was found that about 50 percent of the samples had immune T cells that react to the novel Coronavirus. This finding has suggested that the blood donors' bodies might have the natural ability to fight against the SARS-CoV-2. Researchers found similar results in the UK and Sweden.
As per the British Medical Journal associate editor Dr. Peter Dosh, evidence has been found which suggests that many people may have possessed some protection against the novel Coronavirus.
As reported, in March members of a Skagit County, Washington choir went to their usual practice, unaware of the fact that they had novel Coronavirus. Within a week they tested positive for the virus and another 25 members of the choir also showed symptoms. Later, more people who attended the practice also developed COVID-19 symptoms.
Scientists took this incident as an opportunity to study how Coronavirus infection spreads and why some members did not show any signs earlier. Researchers found that people are more likely to catch the virus, becoming severely ill, if they are exposed repeatedly. But the March incident showed another side of Coronavirus infection. As per the experts, one unexplored explanation would be that some individuals have pre-existing immunity to the virus.
In most affected cities like New York, the proportion of people who have antibodies that would protect them from re-infection is still fairly low, about 23 percent of people tested for antibodies have them, says the report.
As per the researchers, they found the presence of T cells in people from the Netherlands, Germany, and Singapore—these are small studies but they pointed in the same direction. It led the scientists to think that some people may have already developed T cells for other Coronaviruses, which are cross-reactive with SARS-CoV-2 due to sufficient similarities. But still, more research is needed to come to a conclusion.