Long COVID Risk In Kids Found To Double After Their Second COVID-19 Infection

In a study taking data from across the USA, children and adolescents were found to have double the risk of developing long COVID after their second infection with SARS-CoV-2, the virus behind COVID-19. This goes against what many people assumed to be true – that your second run-in with the virus is generally less severe than the first – and provides more evidence that COVID is not necessarily always a “mild” disease in children.

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The data for the study were taken from the RECOVER database, and included patients aged under 21 who were treated at one of 40 different institutions across the United States. The researchers started with over 465,000 medical records.

All eligible patients had a documented COVID infection after January 1, 2022, when the omicron variants were considered the primary circulating variants. The cohort was split into two groups: those on their first COVID-19 infection and those on their second (the first could have been earlier in the pandemic with a different variant).

According to the authors, the study is the first and largest study of this kind to look at long COVID following reinfection in young people. In the final “first infection” group, there were 123,644 children and young people; in the “second infection” group, there were 40,200. The mean age was 8.17 years. 

“Reinfection was associated with a significantly increased risk of an overall PASC [post-acute sequelae of SARS-CoV-2 infection] diagnosis […] and a range of symptoms and conditions potentially related to PASC,” the authors concluded.

We know from previous research that long COVID or post-COVID syndrome can have numerous different symptoms, and these can look different in kids compared with adults. 

In this study, the most common complication observed after infection was myocarditis – inflammation of the heart muscle – the risk of which was found to triple after a second bout of COVID. Blood clots were found to be twice as likely after a second infection.

Other complications that were found to occur at higher rates after reinfection included kidney damage, irregular heartbeat, severe fatigue, mental health issues, skin conditions, and cognitive impairment. 

“These findings emphasize the ongoing risk of PASC with reinfection, regardless of severity, and suggest that the risk of PASC might be cumulative with each successive infection,” write the authors.

This goes against the assumption that reinfection with SARS-CoV-2 tends to be milder than the first infection. Previous research in adults has painted a mixed picture, but there are studies that have drawn similar conclusions. 

One unreviewed preprint posted earlier this year suggested that reinfection “resulted in a roughly 35 percent increase in the incidence of long COVID”, using similar methods to those in the current study. A 2024 study found that reinfections tended to be of similar severity to a first infection, rather than milder, but did find that long COVID was less likely to occur after a second infection. 

One thing that has come up time and again in research is the idea that vaccination can not only prevent infections but can also lessen the risk of post-COVID complications.

“The results of this study further support one of the strongest reasons I give patients, families and physicians about getting vaccinated: More vaccines should lead to fewer infections, which should lead to less long COVID,” said co-author Dr Ravi Jhaveri in a statement.

The Advisory Committee on Immunization Practices (ACIP), which advises the US Centers for Disease Control and Prevention (CDC) on vaccine policy, met recently to vote on its recommendations for COVID-19 vaccines. The upshot was a change in the guidance around vaccination for kids – previously, there was a blanket recommendation for everyone over 6 months. 

At time of writing, the CDC now says, “Parents of children ages 6 months to 17 years should discuss the benefits of vaccination with a healthcare provider.”

The study is published in The Lancet Infectious Diseases.