It happens all the time. Someone has COVID, but other people in their household don’t get infected with the virus. Scientists are investigating the “never COVID” phenomenon, especially as high infectious variants circulate, like Omicron.

Research from the Imperial College London published by Nature Communications in January suggests that people that have a higher T cell count are less likely to contract COVID-19. T cells are cells within the immune system.

Dr. Rhia Kundu, the first author of the study from the Imperial College London’s National Heart & Lung Institute, said in a statement that “we 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.”

However, Kundu maintained that the “best way to protect yourself against COVID-19 is to be fully vaccinated, including getting your booster dose.”

While high levels of T cells are an important discovery, other experts believe that these so-called “never COVID” individuals have a natural immunity to the virus that has been built up from other infections.

Lawrence Young, a professor of molecular oncology at Warwick University, told CNBC that around 20% of common cold infections are the result of common cold coronavirus, which “never COVID” people have naturally acquired immunity to from previous infectious. But he warned that “why some individuals maintain levels of cross-reactive immunity remains unknown.”

Genes may also play an important part in whether or not a person will become infected with the virus, some infectious disease scientists believe.

Research being conducted on the relationship between genetics, the immune system and COVID-19 by Danny Altmann, professor of immunology at Imperial College London, and a team of researchers has shown that there are differences in people’s immune systems. He told CNBC it “makes a difference, at least to whether or not you get symptomatic disease.”

Scientists also agree that the widespread use of vaccination is helping some people avoid COVID infections. While vaccinations and booster shots are not a 100% bet that a person will not get COVID, they do play a role in reducing infections, hospitalizations and deaths from the virus.

Andrew Freedman, an academic in infectious diseases at Cardiff University Medical School, told CNBC that “vaccination does still reduce the chance of catching Omicron and responses do vary from person to person. So some people catch it and others don’t despite very significant exposure.”

Representation. A mask. Pixabay