Long COVID in Children and Youth After Infection or Reinfection with the Omicron Variant: A Prospective Observational Study, 2023 CLoCK consortium

Abstract
To describe the prevalence of long COVID in children infected for the first time (n=332) or reinfected (n=243) with Omicron variant SARS-CoV-2, compared with test-negative children (n=311). 12-16% infected with Omicron met the research definition of long COVID at 3 and 6 months after infection, with no evidence of difference between cases of first-positive and reinfection (pchi-square=0.17).

The emergence of the Omicron (B.1.1.529) variant of SARS-CoV-2 in November 2021 was a major change in the pandemic[[1]]. The variant spread rapidly across the globe, with cases during December 2021 and March 2022 exceeding all previously reported cases[[2]]. Although Omicron caused less severe acute illness in vaccinated populations compared with previous variants, including in children and youth [[3]] its longer-term impact is still relatively unknown. A large case-control study in adults using NICE’s long COVID criterion (i.e. having symptoms for 4+ weeks after the start of acute COVID-19[[4]]), found lower odds of long COVID with Omicron than the Delta variant in the region of 0·24–0·50 depending on age (older adults had greater odds of long COVID) and time since vaccination, corresponding to 4·5% of adults having long COVID after Omicron infection compared to 10·8% after Delta[[2]]. When considering symptoms 12 to 16 weeks after infection, between 4-5% of triple-vaccinated adults self-reported long COVID after infection with either Omicron or Delta variants [[5]].
There is little comparable research regarding the impact of the Omicron variant on long COVID in CYP. The original CLoCk study, the largest national, matched longitudinal study of long COVID in CYP, recruited participants aged 11-17 years, who had PCR tests between September 2020 and March 2021 in England. These non-hospitalised CYP self-report on post-COVID-19 health, and PCR-confirmed SARS-CoV-2 positive CYP are compared to SARS-CoV-2 PCR-negative CYP. Findings from CLoCk and other studies on earlier variants indicates that although most CYP recover well, a minority continue to have impairing symptoms three-months post-infection[[6],[7]]. However, the original CLoCk study was limited by retrospective recall of symptoms at testing and did not include CYP infected with the Omicron variant.
Given that over 90% of CYP have now been exposed to SARs-CoV-2, with large numbers of primary infections and reinfections with Omicron[[8]], it is critical to understand the long-term impact of infection: even if a low proportion of CYP develop long COVID, the scale of Omicron infections and reinfections indicates there could be an unprecedented impact and demand for services. Therefore, our primary objective was to describe the impact of Omicron infection on long COVID in CYP. Specifically, we aimed to (1) determine the proportion of CYP meeting the research definition of long COVID at 3- and 6-months across three infection-status groups: always tested negative (test-negative), first SARS-CoV-2 infection during the period when Omicron was dominant (first-positive) and previous confirmed SARS-CoV-2 infection with reinfection when Omicron was dominant (reinfected); (2) compare symptom profiles across the three groups; and (3) examine differences in long COVID prevalence by age.

https://www.jpeds.com/article/S0022-3476(23)00311-6/fulltext

 

https://threadreaderapp.com/thread/1657887764850040832.html

 

A critical take from epidemiologist and data sleuth Gideon Meyerowitz-Katz:

https://twitter.com/user/status/1657947056118575105


Edited to add: a counter-argument from epidemiologist Deepti Gurdasani:

https://twitter.com/user/status/1658034999919284225