Scientists from around the world are looking at those lucky people that never tested positive for COVID-19 or were asymptomatic despite repeated exposure to the virus. The COVID Human Genetic Effort is an international consortium seeking genetic and immunological causes of the disease. This international group of researchers has three aims: recruit patients with critical COVID-19 pneumonia and their family members that never tested positive or were asymptomatic; search for genetic variants from the patients and family members participating in the study; and study the genetic variants biochemically and the patients’ cells immunologically.

The consortium has recruited approximately 1,000 subjects worldwide. If the researchers can identify a protective genetic factor, it is possible that they could develop drugs to prevent infection and limit the spread of the virus.

At least 20 percent of COVID-19 patients that tested positive were asymptomatic. Researchers at the University of California, San Francisco, conducted research as to why they were able to rapidly clear the virus. They found that of the more than 13,000 people in the study with the human leukocyte antigen (HLA) that tested positive for COVID-19, 10 percent were totally asymptomatic, not even experiencing a scratchy throat. Those with a specific genetic version of HLA were more than twice as likely to have an asymptomatic infection and eight times as likely if they had two copies of the gene.