Asymptomatic SARS-CoV-2 infection by age: A systematic review and meta-analysis

Abstract

Objectives: This systematic review and meta-analysis aimed to estimate the age-specific proportion of asymptomatic SARS-CoV-2 infected persons by year of age. Methods: We searched PubMed, Embase, medRxiv and Google Scholar on 10 September 2020 and 1 March 2021. We included studies conducted during January to October 2020, prior to routine vaccination against COVID-19. Since we expected the relationship between the asymptomatic proportion and age to be non-linear, multilevel mixed-effects logistic regression (QR decomposition) with a restricted cubic spline was used to model asymptomatic proportions as a function of age. Results: A total of 38 studies were included in the meta-analysis. In total, 6556 out of 14850 cases were reported as asymptomatic. The overall estimate of the proportion of people who became infected with SARS-CoV-2 and remained asymptomatic throughout infection was 44.1% (6556/14850, 95%CI 43.3%-45.0%). The asymptomatic proportion peaked in adolescents (36.2%, 95%CI 26.0%-46.5%) at 13.5 years, gradually decreased by age and was lowest at 90.5 years of age (8.1%, 95%CI 3.4%-12.7%). Conclusions: Given the high rates of asymptomatic carriage in adolescents and young adults and their active role in virus transmission in the community, heightened vigilance and public health strategies are needed among these individuals to prevent disease transmission.

Population-based estimates of COVID-19 period prevalence and cumulative monthly incidence in New York City: A comparison of estimates from three surveys, July–August 2020

“…The weighted Healthy NYC population had a significantly higher proportion of low-income respondents than the weighted CHS population, and point estimates suggest a weighted older age distribution in Healthy NYC than CHS, as well. Given that older persons are more likely to have Population-based estimates of COVID-19 period prevalence and cumulative monthly incidence in New York City: A comparis… Survey Practice symptomatic COVID-19 than younger persons (Wang et al 2023) and that low-income persons were at higher risk of SARS-CoV-2 infection (Kim et al 2021;Masterson et al 2023), it is possible that these differences in the weighted populations may have contributed to observed differences in CLI period prevalence between CHS and Healthy NYC. Future analyses may consider alternative weighting approaches that include demographic characteristics associated with SARS-CoV-2 risk and symptoms when using data collected from multiple surveys.…”

Protection against symptomatic disease with the delta and omicron BA.1/BA.2 variants of SARS-CoV-2 after infection and vaccination in adolescents: national observational test-negative case control study, August 2021 to March 2022, England

“…24,33 We and others have demonstrated vaccination offering significant protection against hospitalisation in previously-uninfected adolescents. [14][15][16] Given the high prevalence of asymptomatic infection, 34 and the low risk of severe COVID-19, 1 along with milder disease associated with omicron, 10 it will become more difficult to compare differences in protection from prior infection with different variants alongside different vaccine brands and number of vaccine doses. Using hospitalisations as a marker of severe COVID-19 will also be difficult because of disproportionately higher hospitalisation rates among those with underlying comorbidities compared to healthy adolescents, and high rates of incidental infections among the hospitalised during periods of high community infection rates.…”