Why some don’t get Covid-19 even if they live with someone who is infected

A new study published on Monday in the prestigious journal Nature sheds new light on why some people do not get Covid-19, even if they live with someone infected with the coronavirus. The subjects were found to have increased numbers of T cells – immune cells that are part of our immunity – presumably due to a previous infection with a common cold virus.

The study tracked a number of families in London who had someone tested positive for the coronavirus (using a PCR test). “We then looked to see whether the other family members were infected or not,” said one of the study’s authors, infectiologist Ajit Lalvani from Imperial College London, told Sky News. “We found that people with high levels of T cells continued to test negative. These T cells were caused by previous infection with another coronavirus, such as a cold virus. Our discovery therefore suggests that our T cells are effective in protecting us from Covid-19 infection. “

The study began in September 2020 when only a minority of Britons contracted the coronavirus. 52 people who lived together with a person who tested positive were followed. Participants had to undergo multiple PCR tests to see if they became infected: at the start of the study, and then again four and seven days later.

Blood samples

Blood samples were also taken within six days of exposure to the virus. This made it possible to analyze the number of T cells in the blood that had previously been formed by other coronaviruses, such as the common cold. The researchers found that the 26 people who did not become infected with the virus had significantly higher T-cell counts than the 26 people who did eventually become infected.

According to the authors of the study, the T cells attack proteins inside the coronavirus, not the spike protein outside, which allows the virus to invade our cells. The latter tactic is used by current vaccines to protect us from Covid-19.

The study has already been reviewed by other scientists. The scientists involved call it “an important discovery”, but at the same time warn that “no one should rely on it alone”. Vaccination is still the best protection against Covid-19.


According to the researchers, the discovery could help provide a blueprint for developing new vaccines that will induce longer immunity and protect us from both current and future variants of the coronavirus.

Note * Always consult your doctor or other qualified healthcare professional with any questions about your health or condition. Never disregard or delay a doctor’s advice based on what you read on this website.

This post first appeared on Afrinik.com

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