Scientist aims to find out why some people are 'unaffected by Covid'

A scientist is hoping to fully understand why some people do not develop Covid despite living in close proximity to others with the virus.

Professor Neil Mabbott, an expert in immunopathology at the University of Edinburgh, is hoping a major international study will answer why some people dodge Covid – and believes the answers could lead to new treatments.

He said many factors could contribute to an individual’s own risk of developing the virus, including a person’s age, and how exposed they were to the host when they were at their most infectious.

Prof Mabbott said: “If we can understand why these people never become infected, we might be able to develop new treatments.

“It could be due to genetic differences in genes that affect our susceptibility to the disease. We know how mutations in some genes are linked to developing serious Covid-19 disease.

“It is equally likely that mutations in other genes may influence whether you develop symptoms or not.

“Perhaps they were only exposed to a small amount of virus.

“It is equally possible that the person did become infected, but didn’t develop Covid-19 symptoms, or if they did they were very mild.

“Unknown to themselves, they may even have already had an infection and developed some natural immunity. They may have responded more strongly to the vaccines, or have had more boosters, a different type of vaccine etc.”

Professor Mabbott said that while the same reasons were likely to apply to the Omnicron variant, more studies are required.

He continued: “This variant is much more transmissible. So further studies are necessary to determine whether these individuals have a similar level of protection against Omicron.

“None of this is coronavirus-specific. The same is true for other infections. Some people seem to dodge them or develop only mild symptoms, while others do not.”

A study published last month in Nature Magazine suggested some people develop natural immunity to Covid-19 after having the common cold – a case that Professor Mabbott found “interesting and important”.

He added: “They noted that some health care workers that did not become infected had pre-existing memory T cells that could recognise a core component of the coronavirus that causes Covid-19.

“These cross-protective T cells were probably generated in response to previous infections with the seasonal coronavirus that cause the common cold.

“Since these T cells recognise features of the coronavirus other than the spike protein, it is possible that they may also be effective against Omicron.”