Analysis of data from 4,700 people recovering from a bout of COVID-19 has revealed more insights into who may be most at risk from lingering chronic illness. Referred to as long COVID, scientists are still not clear on exactly what causes the debilitating symptoms – with possibilities numbering into the hundreds – but this new study does shed more light on who may be affected.

Long COVID describes a chronic condition that is present for at least three months after an infection with SARS-CoV-2. Symptoms may be progressive or may come in relapsing and remitting waves. Some people will recover after a period of time, while some have not seen their symptoms fully resolve since developing the condition in the early days of the pandemic in 2020. 

A huge amount of scientific effort has gone into understanding the causes of long COVID and the search for potential treatments that could make a difference, not just for these patients but potentially those with other post-viral syndromes as well. Many unknowns still remain, however, with some of the biggest questions surrounding who may be most at risk of developing long COVID. A new study, led by a team at Columbia University Irving Medical Center, may just have some answers.

“Our study clearly establishes that long COVID posed a substantial personal and societal burden,” said lead author Professor Elizabeth C. Oelsner in a statement. “By identifying who was likely to have experienced a lengthy recovery, we have a better understanding of who should be involved in ongoing studies of how to lessen or prevent the long-term effects of SARS-CoV-2 infection.”

The 4,700 people included in the study had agreed to be part of the Collaborative Cohort of Cohorts for COVID-19 Research, or C4R, which comprises a total of more than 50,000 individuals from across the US who are engaged in long-term research to help us understand as much as possible about the many facets of the COVID-19 pandemic.

The participants were asked to report how long it took them to recover after they had caught COVID. For infections between 2020 and 2023, the median recovery time was found to be 20 days, with more than one in five adults experiencing symptoms for at least three months.

Of those, women and people with preexisting cardiovascular disease were found to make up the greatest proportion. American Indian and Alaska Native participants also more frequently had severe initial infections and longer recovery times.

Infection with an omicron lineage variant, typically associated with milder disease, was linked to a quicker recovery, as was being vaccinated against the virus. “Our study underscores the important role that vaccination against COVID has played, not just in reducing the severity of an infection but also in reducing the risk of long COVID,” said Oelsner. 

Other preexisting conditions that are typically associated with worse outcomes from COVID, such as diabetes and chronic lung disease, were found to be linked to longer recovery times, but this was no longer a statistically significant finding when sex, cardiovascular disease status, vaccination status, and variant exposure were accounted for. 

Interestingly, the study also found no significant link with mental health disorders. “Although studies have suggested that many patients with long COVID experience mental health challenges, we did not find that depressive symptoms prior to SARS-CoV-2 infection were a major risk factor for long COVID,” Oelsner explained.

The main takeaway is that vaccination continues to be the best way of not only avoiding infection in the first place, but of limiting your risk of having a rougher ride with COVID. The current circulating variants are largely offshoots of omicron, which may also be cause for some optimism as these variants were associated with shorter recovery periods. 

Updated vaccines are currently in development to match the latest variants, and the Centers for Disease Control and Prevention (CDC) publishes detailed guidance about when people in different age groups and risk categories should consider their next booster. Vaccine availability varies in different countries, but your local health authority should be able to advise on whether you’re eligible to get a shot. 

The study is published in JAMA Network Open.