In your family or friend circles, you’ve likely found yourselves asking why some people can’t stop getting infected with Covid-19 and why some have somehow entirely avoided the infection all together.
Now, thanks to a collaborative study from University College London, the Wellcome Sanger Institute and Imperial College London, we may finally have an answer to what makes some people more susceptible.
The team worked with unvaccinated volunteers who had no history of COVID and exposed them via nasal spray to a very low dose of the original strain of SARS-CoV-2.
Writing in The Conversation, the researchers explained: “We collected samples from tissue located midway between the nose and the throat as well as blood samples from 16 volunteers.
“These samples were taken before the participants were exposed to the virus, to give us a baseline measurement, and afterwards at regular intervals.”
The researchers were then able to track the evolution of Covid, from pre-infection to recovery in the volunteers.
They said: “To our surprise, we found that, despite all the volunteers being carefully exposed to the exact same dose of the virus in the same manner, not everyone ended up testing positive for COVID.”
Thanks to this revelation, volunteers were divided into three distinct infection groups:
- Sustained infection with cold-like symptoms
- Transient infection with very few symptoms
- Abortive infection with no symptoms
Why some people never get Covid
When the researchers compared the timings of the cellular responses between the three infection groups, they identified distinct patterns. One example they highlighted was that the transiently infected volunteers who only briefly had to virus, there was a “strong and immediate accumulation of immune cells in the nose one day after infection.”
As well as identifying that there was a fast immune response, the researchers identified a specific gene called HLA-DQA2.
They explained: ”[The gene] was expressed (activated to produce a protein) at a much higher level in the volunteers who did not go on to develop a sustained infection and could hence be used as a marker of protection.
“Therefore, we might be able to use this information and identify those who are probably going to be protected from severe COVID.”
Researchers concluded saying: “In essence, our research is a step towards better preparedness for the next pandemic.”
