A German study: T-cell reactivity against COVID-19 found in blood of adults not exposed to the deadly virus!!!

Every day there is some new information about COVID-19 and the immunity against this deadly virus which comes to light. Now, a German study reveals that some people who did not have COVID-19 infection did demonstrate some immunity to the virus. How did these people get an immunity without an exposure? Did this prevent them from developing an active COVID-19 infection?

A German study on immunity against COVID-19 in healthy adults

There is a new study published in Nature last month which revealed that people with no COVID-19 infection still had some immunity against the deadly virus. But from where did these unexposed people get immunity?

T-cells and COVID-19 [Source: The Scientist magazine]
German researchers studied 68 healthy adult people in Germany for immunity against coronavirus. These people wee not exposed to the virus. But despite no exposure, 35% of them showed T-cell reactivity against COVID-19. T-cells play a major role in body immunity against germs. They also are the cells which keep memory to these infections. This implies that the adults had a previous contact with other type of ‘endemic’ and ‘less severe’ coronavirus and acquired this immunity at that time. And it is this T-cell immunity which saves them from a new infection. This is cross-reactivity.

Also, readĀ Is reinfection with COVID-19 real? What does it imply for the world?

More about this new study

The scientists collected blood samples of COVID-19 patients and also of healthy donors. All the study patients were from Germany. 83% of COVID-19 cases had the T-cells reactivity to coronavirus. The healthy donors also had this but in a lesser number of cases. Despite finding these T-cells in the blood of cases of COVID-19 and also in some healthy adults, the researchers are not sure about the benefit and impact of these T-cells on the outcome of the illness.

T-cells and immunity [Source: Technology Networks]
Dr. Amesh Adalja, senior scholar at theĀ Johns Hopkins University Center for Health Security is not a participant in this study. But he opines that more studies are required to confirm the role of T-cells in COVID-19 protection and disease outcome.

The expert opinions

Dr. Amesh said:

“It does appear in this study that there is a significant proportion of individuals that have this cross-reactive T cell immunity from other coronavirus infections that may have some impact on how they fare with the novel coronavirus. I think the big question is trying to jump from the fact that they have these T cells to understanding what the role of those T cells might be,”

Further, he explains:

“We know, for example, children and younger adults are relatively spared from the severe consequences of this disease, and I think that one hypothesis might be that the pre-existing T cells that exist may be much more numerous or more active in younger age cohorts than in older age cohorts,”

T-cells and their role against COVID-19 [Source: TOI]
He adds:

“It’s clear though that the T cell presence doesn’t prevent people from getting infected, but does it modulate the severity of infection? That’s what it appears could be the case.”