So how can their immune system have reactive T cells if they’ve never had Covid-19? They were “probably acquired in previous infections by endemic” coronaviruses, wrote researchers from various institutions in Germany and the United Kingdom in a new study. The use of this T-cell memory from another similar infection to respond to a new infection is called “cross-reactivity”;.
“The main issue is understanding what the role of these T cells may be.”
The new study included blood samples from 18 Covid-19 patients aged 21 to 81 and healthy donors aged 20 to 64 based in Germany. The study showed that coronavirus-reactive T cells were found in 83% of Covid-19 patients.
Although the researchers also found cross-reactive T cells in healthy donors, they wrote in their study that the effect of these cells on the outcome of Covid-19 disease remains unknown.
“This study finds that a significant proportion of people who have this interactive T-cell immunity to other coronavirus infections may have some influence on how they match the new coronavirus. I think the big question is trying to move away from they have these T cells to understand what the role of these T cells may be, ”Adalya said.
“We know, for example, that children and young people are relatively deprived of the serious consequences of this disease, and I think one hypothesis may be that existing T cells may be much more numerous or active at a younger age in the cohort than in older cohorts, “Adalya said.
“And if you can compare people to possibly severe and mild disease, try looking at those people’s T cells and saying, ‘Are people who have serious illnesses less likely to cross-react with T cells than people?’ who have mild disease may have more cross-responsive T cells? “I think there is biological plausibility in this hypothesis,” he said. That seems to be the case. “
So far, during the coronavirus pandemic, much attention has been paid to antibodies to covidor-19 and their role in the formation of immunity against the disease.
“Here’s a study that says there may actually be some cross-reaction – some pump refueling, if you will – with the usual coronaviruses that cause colds in humans, and there may be some cross-reaction with the Covid virus that causes so much damage. This in itself is intriguing, because we thought in terms of antibodies that there weren’t many intersections at all, “Schaffner said.
“It’s not very strange, because it’s all family members. It’s like they are cousins in the same family,” he said. “Now we need to understand whether this has an effect in clinical practice … Does it make it more or less likely that a person infected with Kovid will actually develop the disease? And does it have the consequences of vaccination? Development?”
“Almost everyone in the world has been exposed to the coronavirus”
Adalia added that he was not surprised to see this T-cell cross-reactivity in study participants who were not exposed to a new coronavirus called SARS-CoV-2.
“SARS-CoV-2 is the seventh human coronavirus to be detected. The four human coronaviruses are what we call community-acquired coronaviruses, and these four together account for 25% of our colds,” Adala said. “Virtually everyone in the world has been exposed to the coronavirus, and because they are all in the same family, some cross-reactive immunity develops.”
The new science is not the only document that suggests a certain level of immunity among some people to the new coronavirus.
Seth and Crotty wrote that “it has now been established that the previous immune reactivity of SARS-CoV-2 in the general population exists to some extent. This is a hypothesis, but has not yet been shown to be related to immunity to the common cold coronavirus.”