Abstract
Over 40% of the coronavirus disease 2019 (COVID-19) COVID-19 patients were asymptomatically infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the immune responses of these asymptomatic individuals is a critical factor for developing the strategy to contain the COVID-19 pandemic. Here, we determined the viral dynamics and antibody responses among 143 asymptomatic individuals identified in a massive screening of more than 5 million people in eight districts of Wuhan in May 2020. Asymptomatic individuals were admitted to the government-designated centralized sites in accordance with policy. The incidence rate of asymptomatic infection is ~2.92/100,000. These individuals had low viral copy numbers (peaked at 315 copies/mL) and short-lived antibody responses with the estimated diminish time of 69 days. The antibody responses in individuals with persistent SARS-CoV-2 infection is much longer with the estimated diminish time of 257 days. These results imply that the immune responses in the asymptomatic individuals are not potent enough for preventing SARS-CoV-2 re-infection, which has recently been reported in recovered COVID-19 patients. This casts doubt on the efficacy of forming “herd-immunity” through natural SARS-CoV-2 infection and urges for the development of safe and effective vaccines.
Highlights
As of December 23, 2020, the coronavirus disease 2019 (COVID-19)pandemic, caused by SARS-CoV-2 infection, has affected more than 78 million people leading to over 1.7 million death cases around the world
It was recently reported that the breadth and magnitude of T cell responses were significantly higher in severe as compared with mild cases, while higher proportions of SARS-CoV-2-specific CD8+ T cells were observed in mild cases.[16]
The duration of anti-SARS-CoV-2 immune responses among COVID-19 patients appear to be correlated with the duration of virus infection
Summary
Pandemic, caused by SARS-CoV-2 infection, has affected more than 78 million people leading to over 1.7 million death cases around the world. It is estimated that to reach the herd immunity, about 60–75% of the population need to be infected for attaining the population immunity This would lead to millions of extra COVID-19 deaths and long-term complications that are difficult to be estimated. Another critical factor for consideration when discussing application of “herd immunity” is the duration of protective immune responses in people infected by SARS-CoV-2. Results from this study Dynamic profiles of anti-SARS-COV-2 antibody in the cohort of indicate that antibody responses among asymptomatic individuals asymptomatic SARS-CoV-2 infection may not be potent and persistent enough to prevent these people The anti-SARS-CoV-2 IgG antibody level was plotted for the Cohort from SARS-CoV-2 re-infection This argues against application of 1 of asymptomatic SARS-CoV-2 infection every 3 days (Fig. 2a). The the strategy of “herd immunity” and urges development of positive rate started at 86.4% (95% CI 62.6–95.3%) for the first effective vaccines and anti-viral drugs
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