New Delhi: Children reinfected with SARS-CoV-2, the virus that causes COVID-19, are twice as likely to develop long COVID compared with those infected only once, according to a large US study published in 'The Lancet Infectious Diseases'.

The study, which examined the health records of more than 4,60,000 children and adolescents across 40 paediatric hospitals, found that after an initial infection, about 904 children per million developed long COVID within six months. Following a reinfection, that figure rose sharply to around 1,884 per million.

Researchers noted that affected children were more likely to experience rare but persistent, and sometimes serious, complications, including heart inflammation (myocarditis), blood clots, kidney injury, fatigue, cognitive difficulties and respiratory problems.

“These findings add to previous evidence linking paediatric long COVID to multisystem effects and highlight the need to promote vaccination in younger populations and support ongoing research to better understand post-acute sequelae of SARS-CoV-2 Infection (long COVID), identify high-risk subgroups, and improve prevention and care strategies,” researchers from the universities of Pennsylvania, Iowa and California said. They stressed the need for continued research to identify high-risk groups and improve strategies for prevention and care.

The team analysed records from January 2022 to October 2023, when the highly transmissible Omicron variant was dominant. By comparing health outcomes following children’s first and second documented infections, they were able to isolate the risks linked to reinfection.

While vaccines and other measures cannot fully prevent COVID-19, the researchers said they remain the most effective way to reduce both primary infections and reinfections and, in turn, lower the likelihood of long-lasting symptoms in children.

They concluded that the findings reinforce the urgency of increasing COVID-19 vaccination coverage among children and adolescents to limit long-term health risks.

IANS