Study: Vaccination reduces children’s long COVID risk by 57%
Key takeaways:
- Children were around half as likely to develop one or more long COVID symptoms if they were vaccinated.
- Vaccinated children were 75% less likely to experience long COVID symptoms that affected daily function.
Children vaccinated against COVID-19 were more than 50% less likely to develop at least one long COVID symptom compared with unvaccinated children, according to findings published in JAMA Network Open.
“An estimated 1% to 3% of children infected with SARS-CoV-2 will develop” long COVID, Anna R. Yousaf, MD, a medical officer in the CDC’s National Center for Immunization and Respiratory Diseases, and colleagues wrote. “Although children typically experience mild symptoms from SARS-CoV-2 infection, [long COVID] can develop following mild or severe COVID-19 illness and [long COVID] symptoms can be prolonged, debilitating and contribute to school absenteeism.”
Their case-control study included 622 children aged 5 to 17 years (mean age, 10 years) who tested positive for SARS-CoV-2 from Dec. 20, 2021, through March 7, 2023, and were eligible to receive a COVID-19 messenger RNA vaccine. The researchers compared a group of 28 participants (46% girls) with at least one long COVID symptom with 594 people (48% girls) who did not experience long COVID.
A larger proportion of children in the control group were vaccinated against COVID-19, compared with those who had long COVID (77% vs. 57%; P = .05), according to the researchers. At baseline, more participants with long COVID reported good, fair or poor baseline health, rather than excellent or very good, than controls (25% vs. 9%), “suggesting that participants with poorer baseline health may be more likely to report” long COVID, the authors wrote.
More than half of participants with long COVID (57%) reported at least one symptom that impacted their day-to-day function.
In an adjusted analysis, children who were vaccinated were 57% less likely to have at least one long COVID symptom (adjusted OR = 0.43; 95% CI, 0.19-0.98) and 73% less likely to experience two or more symptoms (aOR = 0.27; 95% CI, 0.1-0.69), Yousaf and colleagues reported. Additionally, vaccinated children were 72% less likely to report respiratory long COVID symptoms (aOR = 0.28; 95% CI, 0.1-0.75) and 75% less likely to have symptoms that impacted their daily function (aOR = 0.25; 95% CI, 0.08-0.74).
The researchers noted that several children in the study who developed long COVID had mild symptoms or no symptoms at the time they tested positive for SARS-CoV-2 infection.
“Surveys have shown that one reason behind parental COVID-19 vaccine hesitancy is the idea that COVID-19 in children is usually a mild illness and therefore vaccination is not necessary,” they wrote. “However, even mild or asymptomatic SARS-CoV-2 infection can result in postinfectious sequelae.”
“Because both case and control participants had SARS-CoV-2 infection, the overall protection from post-COVID-19 condition is likely even higher, as these estimates do not account for prevention of SARS-CoV-2 infection by vaccination,” Yousaf and colleagues wrote.
Perspective
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The findings are consistent with the body of evidence showing that in 2021-2022 vaccines reduced the risk of long COVID in children and in adults.
The major knowledge gap is whether vaccines in 2025 or 2026 or later will still offer protection. The virus is evolving, and people have been exposed to multiple infections; the effectiveness of vaccines in reducing risk of adverse events in the acute and post-acute phase should be continuously evaluated.
This study included a cohort of kids in 2021-2022. We cannot rely on evidence from 2021 and 2022 to make decisions in 2025. In my view, the evidence base is outdated. We cannot assume what worked then will still work in the same way and to the same extent in 2025. Many things have changed, including SARS-CoV-2 itself and population-level immunity.
We need updated evidence. I would like to know whether vaccines still offer protection in 2025 and in whom. In other words, who would benefit from vaccines in 2025?
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