Long Covid may affect 5.8 million children in the U.S., according to an article published on Wednesday in the journal Pediatrics. That’s a large number. It’s also a number that stands in contrast to other published estimates of pediatric long Covid. So, who’s right?
Let’s begin by exploring how the authors of this article arrived at their number. As with any estimate, they started with a few basic assumptions. They assumed that 20% of Covid-19 cases occur in children and that the prevalence of long Covid, or postacute sequelae of SARS-CoV-2, in children is 10-20%.
According to data provided by KFF, the cumulative number of Covid-19 cases in the U.S. at the end of January 2024 was approximately 105 million. If 20% of those cases occurred in children and 20% of those children developed long Covid, then about 4.2 million children in the U.S. should be affected. That’s reasonably close to the number cited by the authors.
However, it’s unclear how the authors determined that 10-20% of children with Covid-19 will develop long Covid. They state that experts, “reviewed the literature for relevant pediatric studies and summarized the findings.” That’s all we really know. They list 98 articles that were reviewed. Presumably, their careful review of these articles led the authors to determine that the prevalence is 10-20%. But we don’t have any information about why these articles were selected and, conversely, why other articles may not have been selected.
So, what have other researchers concluded? The numbers vary wildly. Dr. Suchitra Rao, the corresponding author of the current report, noted that these disparate estimates can arise from “different populations being evaluated, different definitions of PASC/long Covid, and variability in study design.”
Indeed, several studies have estimated that the prevalence of long Covid in children is relatively low. For example, data published by the CDC suggests that the prevalence of long Covid in children is 1.3%. This figure was obtained from a survey of roughly 7,500 people and differs substantially from the 10-20% rate used by the authors of the present article. If the prevalence is 1.3%, then the number of children affected by long Covid may be closer to half a million, a much smaller number. Interestingly, even some authors of the current paper previously concluded in an article published in JAMA Pediatrics that, “PASC in children appears to be low.”
When asked about the CDC data, Dr. Rao commented that the CDC study, “used a more specific definition,” of long Covid, which probably led to their lower prevalence estimate. That’s a valid point. Without a standard definition, it’s hard to compare the results.
It’s worth noting that the article in Pediatrics is a review and not a study. According to the journal website, review articles provide an overview of a topic. The article also is not a systematic review or a meta-analysis. For these types of publications, authors must clearly state criteria for including and excluding literature being evaluated. The reader, then, can more critically evaluate the information.
Long Covid remains one of the more vexing aspects of Covid-19. Numerous symptoms affecting various organ systems have been reported. Researchers still can’t predict who is at risk of developing these debilitating sequelae. And clinicians still cannot provide relief. The presence of long Covid in children is a significant public health problem that must be addressed. The extent of the problem, however, remains unknown.