Researchers believe that genetic factors have become more important in Covid-19 infections. — AFP
PUBLIC RELATIONS executive Dee (not her real name) was down with Covid -19 again, her third time, after a night of partying for her friend’s 30th birthday last December. She was alone, however, in the infection; the birthday girl and their other three friends tested negative for the SARS-CoV-2 virus. All had received four doses of vaccination, including two booster jabs.
“Am I just unlucky?” Dee lamented.
As many have started to realise, Covid-19 doesn’t always affect people the same way. It has also been noted by the medical fraternity according to a report by CNN: if someone gets sick, not everyone in that person’s close social circle will get infected – even if they recently spent time together. But why?
Researchers believe that genetic factors have become more important, CNN reported, pointing to a paper recently published in peer-reviewed scientific journal Nature Communications: researchers found that at the beginning of the pandemic, environmental factors like social distancing, isolation, hand washing, mask wearing, and vaccination were big factors in whether people got infected, while over time, genetic factors are playing a more important role.
Now, genetics may account for anywhere from 30% to 70% of one’s chance of getting Covid-19, they concluded.
To reach that estimate, the researchers from Columbia University and the Cedars-Sinai Medical Centre delved into the different factors at play, from genetics to public health interventions, all of which affect how a virus spreads from one person to another.
They studied the health records from more than 12,000 people (who came from about 5,600 families total) who tested positive for Covid-19 at a large New York City hospital from February 2020 to October 2021.
They also categorised each person’s potential exposure by weighing factors like who lived in their household, contact with their extended family, and what kind of housing they had. This is to capture the role that non- genetic factors, such as a person’s environment, play in their chance of getting infected with the virus or how severely ill they got if they were infected.
At the beginning of the study, it was reported, the researchers estimated that genetics accounted for about 33% of a person’s likelihood of getting infected, while by the end, genetics accounted for 70%. That’s a huge jump from previous studies, which estimated that a person’s genes only explained about 1% of their likelihood of infection. This indicates that more genes are likely contributing than previously thought.
“We don’t know what the specific genetic variants are yet, but we do know there are other genetic variants that confer some sort of susceptibility, which might explain why some people are reinfected multiple times and others seem resistant even if they are family members living together,” Nicholas Tatonetti, associate professor of computational biomedicine at Cedars-Sinai and senior author of the paper said.
Why did genetics gain a bigger role as the pandemic progressed?
At the beginning of the outbreak, public health measures such as mask mandates, lockdowns, and isolation practices had a bigger influence on who got infected, since nearly everyone was encountering SARS-CoV-2 for the first time and had little immunity to fend off the virus. But as people became infected and vaccinated, those environmental factors became more homogenised, and genetic factors related to people’s different immune responses began to emerge as the more prominent driver of who got infected and to what extent.
It’s not an exact science, but this type of modelling can help public health experts understand when interventions like masks are most impactful, Tatonetti told CNN.
And it seems to be at the start of outbreaks.
“These results show that public health practices really do matter, and they worked,” he was quoted as saying.
That’s important to remember, since genetic factors are out of our control – while behaviour changes can help us tip the balance, at least somewhat, in our favour. — Agencies
