Asymptomatic infection and transmission of COVID-19 among clusters: systematic review and meta-analysis

Abstract

Objectives Countries throughout the world are experiencing COVID-19 viral load in their populations, leading to potential transmission and infectivity of asymptomatic COVID-19 cases. The current systematic review and meta-analysis aims to investigate the role of asymptomatic infection and transmission reported in family clusters, adults, children and healthcare workers, globally. Study design Systematic review and meta-analysis. Methods An online literature search of PubMed, Google Scholar, medRixv and BioRixv was performed using standard Boolean operators, and included studies published up to 17 August 2021. For the systematic review, case reports, short communications and retrospective studies were included to ensure sufficient asymptomatic COVID-19 transmission data were reported. For the quantitative synthesis (meta-analysis), participant data from a collection of cohort studies focusing on groups of familial clusters, adults, children and healthcare workers were included. Inconsistency among studies was assessed using I 2 statistics. The data synthesis was computed using the STATA 16.0 software. Results This study showed asymptomatic transmission among familial clusters, adults, children and healthcare workers of 15.72%, 29.48%, 24.09% and 0%, respectively. Overall, asymptomatic transmission was 24.51% (95% confidence interval [CI]: 14.38, 36.02) among all studied population groups, with a heterogeneity of I 2 = 95.30% (p <0.001). No heterogeneity was seen in the population subgroups of children and healthcare workers. The risk of bias in all included studies was assessed using the Newcastle Ottawa Scale. Conclusions To minimise the spread of COVID-19 within the community, this study found that following screening of asymptomatic cases and their close contacts for chest CT scan (for symptomatic patients), even after negative nucleic acid testing, it is essential to perform a rigorous epidemiological history, early isolation, social distancing and an increased quarantine period (a minimum of 14–28 days). This systematic review and meta-analysis supports the notion of asymptomatic COVID-19 infection and person-to-person transmission, and suggests that this is dependent on the varying viral incubation period among individuals. Children, especially those of school age (i.e. <18 years), need to be monitored carefully and follow mitigation strategies (e.g. social distancing, hand hygiene, wearing face masks) to prevent asymptomatic community transmission of COVID-19.

Clinical and Genetic Characteristics of Coronaviruses with Particular Emphasis on SARS-CoV-2 Virus

“…SARS-CoV-2 is transmitted mainly by droplets during face-to-face exposure (by sneezing or coughing); however, transmission is possible through direct contact with the infected person or with contaminated surfaces, although it is a marginal transmission route ( Wiersinga et al 2020 ; Ravindra et al 2022 ). In addition, the possibility of fecal-oral transmission has been suggested, which may be evidenced by the presence of SARS-CoV-2 RNA in rectal swabs or stools (assayed by RT-PCR) ( Cheung et al 2020 ; Bwire et al 2021 ).…”

Modelling patterns of SARS-CoV-2 circulation in the Netherlands, August 2020-February 2022, revealed by a nationwide sewage surveillance program

“…The virus can cause the respiratory and systemic disease COVID-19, but in general severity and progression of the disease are variable [1], depending on host risk factors [2] and pathogen variants [3]. It is known that transmission can also occur via asymptomatic or pre-symptomatic individuals [4]. These characteristics hamper effective epidemiological surveillance for the infection dynamics, as case notifications are biased, depending on strain-dependent severity of disease, willingness to get tested, testing capacity, and public health policies.…”

SARS-CoV-2 testing in patients with low COVID-19 suspicion at admission to a tertiary care hospital, Stockholm, Sweden, March to September 2020

“…Symptom-based testing for COVID-19 has shown to be specific but not sensitive, since absence of clinical symptoms does not rule out infections [ 5 ]. Furthermore, during the early pandemic, findings emerged suggesting that the virus may spread from asymptomatic or pre-symptomatic individuals [ 6 , 7 ]. SARS-CoV-2 testing approaches focussed solely on the presence of symptoms are therefore unlikely to be adequate to prevent nosocomial spread if there is a sustained community transmission risk [ 5 ].…”