Abstract
PurposeThe COVID-19 pandemic has led to over 92 million cases and 1.9 million deaths worldwide since its outbreak. Public health responses have focused on identifying symptomatic individuals to halt spread. However, evidence is accruing that asymptomatic individuals are infectious and contributing to this global pandemic. MethodsObservational data of 320 index cases and their 1289 positive contacts from the National COVID-19 Database in Bahrain were used to analyze symptoms, infectivity rate and PCR Cycle threshold (Ct) values. ResultsNo significant difference (p = 1.0) in proportions of symptomatic (n = 160; 50.0%) and asymptomatic index cases (n = 160; 50.0%) were seen; however, SARS-CoV-2 positive contact cases were predominantly asymptomatic (n = 1127, 87.4%). Individuals aged 0−19 years constituted a larger proportion of positive contact cases (20.8%) than index cases (4.7%; p < 0.001). A total of 22% of the positive contacts were infected by symptomatic male index cases aged between 30−39 years. The total numbers of exposed contacts (p = 0.33), infected contacts (p = 0.81) and hence infectivity rate (p = 0.72) were not different between symptomatic and asymptomatic index cases. PCR Ct values were higher in asymptomatic compared to symptomatic index cases (p < 0.001), and higher in asymptomatic compared to symptomatic positive contacts (p < 0.001). No differences between the infectivity rates of index cases with Ct values <30 and values ≥30 were observed (p = 0.13). ConclusionThese data reveal that the high asymptomatic incidence of SARS-CoV-2 infection in Bahrain and subsequent positive contacts from an index case were more likely to be asymptomatic, showing the high “silent” risk of transmission and need for comprehensive screening for each positive infection to help halt the ongoing pandemic.
Highlights
SARS-CoV-2, the virus causing Coronavirus disease 2019 (COVID-19), has infected more than 92 million people and lead to the death of more than 1.9 million people worldwide since its outbreak in December 2019 (WHO, 2020)
A recent study by Arons et al described a COVID-19 outbreak in a Washington nursing facility: after a symptomatic healthcare worker tested positive for the virus, a facility-wide SARS-CoV-2 screen was carried out, which showed over half (56%) of workers who tested positive for SARSCoV-2 were asymptomatic, of which 71% had viable virus by culture (Arons et al, 2020)
This study demonstrates the need to take this reservoir of asymptomatic infections as a serious threat to the community spread of SARS-CoV-2
Summary
SARS-CoV-2, the virus causing Coronavirus disease 2019 (COVID-19), has infected more than 92 million people and lead to the death of more than 1.9 million people worldwide since its outbreak in December 2019 (WHO, 2020). Pandemic, and management of symptoms is an essential part of treatment Both the World Health Organization (WHO) and the Center for Disease Control and Prevention (CDC) have issued guidance for the identification of COVID-19 based on symptoms (Sohrabi et al, 2020). A recent study by Arons et al described a COVID-19 outbreak in a Washington nursing facility: after a symptomatic healthcare worker tested positive for the virus, a facility-wide SARS-CoV-2 screen was carried out, which showed over half (56%) of workers who tested positive for SARSCoV-2 were asymptomatic, of which 71% had viable virus by culture (Arons et al, 2020). This study demonstrates the need to take this reservoir of asymptomatic infections as a serious threat to the community spread of SARS-CoV-2
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