Why some people get COVID-19 infection, while others are healthy

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In a new study from Imperial College London, researchers found that people with higher levels of T cells (a type of cell in the immune system) from common cold coronaviruses were less likely to become infected with SARS-CoV-2, the virus that causes Covid-19.

They found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against Covid-19 infection.

The team cautions that while this is an important discovery, it is only one form of protection.

No one should rely on this alone. Instead, the best way to protect against Covid-19 is to be fully vaccinated, including getting the booster dose.

Previous research suggests these individuals have naturally acquired immunity from previous infections with common cold coronaviruses.

Around 20% of common cold infections are due to common cold coronaviruses, but why some individuals maintain levels of cross-reactive immunity remains unknown.

Researchers say that as well as a degree of immunity provided by prior exposure to coronaviruses, one’s Covid vaccination status is also likely to be a factor as to whether some people are more susceptible to Covid than others.

Covid vaccines have been proven to reduce severe infections, hospitalizations, and deaths, and remain largely effective against known variants of the virus.

However, they are not 100% effective in preventing infection and the immunity they provide wanes over time and has been somewhat compromised by the omicron variant.

Another important factor is genes. Studies have found that variations between people’s immune systems make a difference, at least to whether or not people get a symptomatic disease.

Researchers say that future studies into so-called never Covid individuals will help in developing a better understanding of the immune response to SARS-CoV-2.

If you care about COVID, please read studies about why people with blood Type O less likely to get COVID-19, and a new drug that could prevent COVID-19.

For more information about health, please see recent studies that vitamin D can be cheap treatments for COVID-19, and results showing why smokers have a lower risk of COVID-19.

The study was conducted by Dr. Rhia Kundu et al.

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