Differential COVID-19 infection rates in children, adults, and elderly: Systematic review and meta-analysis of 38 pre-vaccination national seroprevalence studies

Abstract

Background Debate exists about whether extra protection of elderly and other vulnerable individuals is feasible in COVID-19. We aimed to assess the relative infection rates in the elderly vs the non-elderly and, secondarily, in children vs adults. Methods We performed a systematic review and meta-analysis of seroprevalence studies conducted in the pre-vaccination era. We identified representative national studies without high risk of bias through SeroTracker and PubMed searches (last updated May 17, 2022). We noted seroprevalence estimates for children, non-elderly adults, and elderly adults, using cut-offs of 20 and 60 years (or as close to these ages, if they were unavailable) and compared them between different age groups. Results We included 38 national seroprevalence studies from 36 different countries comprising 826 963 participants. Twenty-six of these studies also included pediatric populations and twenty-five were from high-income countries. The median ratio of seroprevalence in elderly vs non-elderly adults (or non-elderly in general, if pediatric and adult population data were not offered separately) was 0.90-0.95 in different analyses, with large variability across studies. In five studies (all in high-income countries), we observed significant protection of the elderly with a ratio of <0.40, with a median of 0.83 in high-income countries and 1.02 elsewhere. The median ratio of seroprevalence in children vs adults was 0.89 and only one study showed a significant ratio of <0.40. The main limitation of our study is the inaccuracies and biases in seroprevalence studies. Conclusions Precision shielding of elderly community-dwelling populations before the availability of vaccines was indicated in some high-income countries, but most countries failed to achieve any substantial focused protection. Registration Open Science Framework (available at: https://osf.io/xvupr )

Coronavirus disease 2019 vaccine in pediatric post‐kidney transplantation

“…Unlike for the adult transplant population 45,54–56 adding a third dose for the pediatric kidney transplant recipients may not be necessary to improve seroconversion rates (i.e., S antibody titer). Despite the limitation of the small sample size, it is noteworthy that the seroconversion after a two‐dose series was significantly better in younger age groups than that in the adult population, supporting the argument that pediatric SOT recipients can mount a more robust measured antibody response to vaccination than adult patients, as is consistent with prior reports 21,42,57,58 …”

“…better in younger age groups than that in the adult population, supporting the argument that pediatric SOT recipients can mount a more robust measured antibody response to vaccination than adult patients, as is consistent with prior reports. 21,42,57,58 Immunosuppression management in SOT recipients is characterized by balancing the risk of rejection with the risk of infection. Our pediatric solid organ transplant protocol stratifies patient based on their immunological risk in to high immunological and low immunological risk.…”

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“…The ability to selectively protect the elderly population is also uncertain. Evidence from seroprevalence studies from the first two COVID‐19 waves suggests that some countries managed to offer substantial precision shielding to the elderly, but most countries had relatively similar infection rates among the elderly and non‐elderly 21 . With far greater sensitization about the extremely steep age risk gradient of IFR and with the past lessons of extremely high fatalities in LTCFs 22 elsewhere, including prominently in Hong Kong, one hopes that China avoids the past mistakes of other countries.…”

“…Evidence from seroprevalence studies from the first two COVID-19 waves suggests that some countries managed to offer substantial precision shielding to the elderly, but most countries had relatively similar infection rates among the elderly and non-elderly. 21 With far greater sensitization about the extremely steep age risk gradient of IFR and with the past lessons of extremely high fatalities in LTCFs 22 elsewhere, including prominently in Hong Kong, one hopes that China avoids the past mistakes of other countries. Even though China has a smaller share of its population residing in LTCFs than Hong Kong and South Korea, a large share of avoidable deaths depends on whether these facilities can be effectively protected.…”

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