“What we are looking for is potentially very rare genetic variants with a very big impact on the individual,” said András Spaan, a clinical microbiologist and fellow at the Rockefeller University in New York who is spearheading a search for genetic material responsible for coronavirus resistance.
Neither of Strickland’s parents have had the virus, nor has her twin sister who works as a primary care doctor. When both she and one of her twin sons managed to evade illness even after her other son endured a covid infection inside their 1,200-square-foot house, Strickland began to suspect she may have a natural immunity to the virus. So she sought out the scientific study looking at the genetic makeup of people like her who never contracted the coronavirus despite repeated exposures.
Studying the genes and other biological traits of people who never catch the coronavirus could shed light on how the virus develops, or how it infects the human body and makes people sick, said Jennifer Nuzzo, a professor of epidemiology at the Brown University School of Public Health. The findings could lead to better drugs and more targeted public health advice.
Scientists don’t know why some people might be impervious to the coronavirus, but Nuzzo said one hypothesis could be that some individuals have fewer receptors in their noses, throats and lungs for the virus to bind to. Other possible explanations could be prior exposure to a related virus or simply being born with an immune system better suited to fighting SARS-CoV-2.
But finding individuals who have truly never had a coronavirus infection — not just those who had an asymptomatic infection or less severe case of covid-19 and did not know they had contracted the virus — is tricky.
“Those people should be exceedingly rare in the United States at this point,” said Christopher Murray, director of the Institute for Health Metrics and Evaluation at the University of Washington and who helps develop models that estimate how far the virus has spread.
Antibody tests can rule out people who have an immune response to the virus, but some of those tests cannot distinguish between people who have antibodies because of vaccines and those who have had the coronavirus, Murray said. The accuracy of many antibody tests wanes over time, so they may not identify someone who had been infected months ago, he added.
On a recent afternoon, the 52-year-old was one of the few people wearing a mask in the District’s bustling Union Market, where he works at Banana Blossom Bistro. Taking precautions such as masking and getting vaccinated are part of the reason McClellan thinks he has managed to avoid testing positive. But he also thinks it may be his naturally strong immune system.
People who always wear masks in indoor public spaces, stay up to date on vaccines and boosters, test frequently, and avoid high-risk gatherings or travel may have had fewer chances to catch the virus, Wachter said. Low levels of community spread in certain regions or the ability to work from home may also have protected some individuals better than others, he said.
Lanae Erickson, an executive at a D.C. think tank, has taken a lot of steps over the pandemic to reduce her exposure risks. She used to ride Amtrak three times a week to Richmond, where her partner lives with her two children. When the pandemic hit, Erickson bought a car to avoid traveling with people who might have covid. She worked virtually and only recently has returned to the office for occasional meetings. When she goes into work, she masks up. She’s fully vaccinated.
This past Christmas, when the omicron variant was raging, her partner’s 12- and 14-year-old children both tested positive. But Erickson and her partner remained coronavirus-free and never felt sick. They spent Christmas socially distanced — presents wiped down with disinfectant and left on doorsteps.
During the worst of the covid surges, James Park was seeing 12 to 18 covid patients a day at the University of Pennsylvania hospital in Philadelphia where he works as a doctor and associate professor of clinical medicine. The anxiety was full-throttle, particularly in the early days when so little about the coronavirus was known. There was an eight-step protocol for leaving a patient’s room and changing out of protective gear.
Park would test another half-dozen times or so during the pandemic’s first 18 months and never had a positive test, despite some of his colleagues falling ill with the virus. At-home tests have also all been negative. Park said he trusted the precautions his employer had in place to keep front-line workers safe.
At home, he and his family took safety seriously, as well. They always masked in public indoor places and ate in restaurants only two or three times. They occasionally had friends over for outdoor gatherings. Like many Americans, they bought a fire pit for backyard get-togethers. The schools Park’s children attend have ended mask mandates, but his kids continue to wear masks indoors. Everyone in the family is vaccinated.