There is still a lot to learn about the risk factors for Long COVID. In addition to the severity of your initial COVID-19 infection, the latest data suggest being a woman, having excess fat tissue, and the presence of a common virus may also be relevant.* 

Long COVID affects millions

Approximately 30% of people infected with SARS-CoV-2, the virus that causes COVID-19, will go on to experience long-term symptoms. According to a study published in the Journal of the American Medical Association, many COVID long-haulers recover in about three months, but some people can experience side effects for a year or more.

Anyone with COVID-19 can develop Long COVID, but it seems to be more common among those with a severe initial infection. As scientists continue studying why some people experience long-term symptoms, emerging evidence suggests certain risk factors may also be relevant.

Possible risk factors for Long COVID

Scientists still don’t know what directly causes Long COVID, but data suggest certain factors may increase your risk of developing ongoing symptoms. 

Being female

Multiple studies suggest that women are more likely to experience Long COVID than men, but it’s still unclear why. Sabra Klein, Ph.D., a microbiologist and professor of molecular biology and immunity at Johns Hopkins School of Public Health, says several factors may be involved:

• Women tend to have stronger reactions to bacteria, viruses, and other pathogens.
• Autoimmune diseases are more common among women, and some scientists believe the SARS-CoV-2 virus could cause the body to mistakenly attack healthy cells. 
• Women typically have more fat tissue than men, which some believe may harbor the virus after infection.
• Women generally seek medical care more often than men and may be more aware of changes they’re experiencing.

Klein says she believes both biological and behavioral factors are important to consider when studying a person’s risk for developing Long COVID. 

The mono virus

Mononucleosis, more commonly called “mono”, is a common infection whose symptoms can mimic a cold or the flu. It is most commonly caused by a virus called the Epstein-Barr virus (EBV). It’s estimated that up to 90% of Americans are infected with EBV at some point in their lives, and once someone is infected, the virus stays in the body, even beyond recovery.

Experts say inflammation caused by Long COVID can reactivate dormant EBV in some people, but not everyone will experience this. Some scientists also believe reactivated EBV can trigger a condition similar to Long COVID known as chronic fatigue syndrome, but more research is needed.

Excess fat tissue

Having excess adipose tissue, or body fat, can increase your risk of developing Long COVID, though scientists don’t fully understand why. 

Lab studies have shown that the SARS-CoV-2 virus reproduces in adipose tissue, and some scientists believe this could lead to ongoing symptoms. Other researchers are studying whether reducing the amount of leptin, an inflammation-promoting hormone produced by fat cells, could lower inflammation caused by Long COVID.

Infectious disease expert Lawrence Purpura, M.D., says uncovering who may be at risk for Long COVID is a complicated problem to solve, but reminds long-haulers that most people do recover.

*Associated Press. (2022, December 31). Long COVID: Could mono virus or fat cells be playing roles? WUSF Public Media. https://wusfnews.wusf.usf.edu/health-news-florida/2022-12-31/long-covid-could-mono-virus-or-fat-cells-be-playing-roles