Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections

Abstract

The clinical features and immune responses of asymptomatic individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well described. We studied 37 asymptomatic individuals in the Wanzhou District who were diagnosed with RT-PCR-confirmed SARS-CoV-2 infections but without any relevant clinical symptoms in the preceding 14 d and during hospitalization. Asymptomatic individuals were admitted to the government-designated Wanzhou People's Hospital for centralized isolation in accordance with policy 1 . The median duration of viral shedding in the asymptomatic group was 19 d (interquartile range (IQR), 15-26 d). The asymptomatic group had a significantly longer duration of viral shedding than the symptomatic group (log-rank P = 0.028). The virus-specific IgG levels in the asymptomatic group (median S/CO, 3.4; IQR, 1.6-10.7) were significantly lower (P = 0.005) relative to the symptomatic group (median S/CO, 20.5; IQR, 5.8-38.2) in the acute phase. Of asymptomatic individuals, 93.3% (28/30) and 81.1% (30/37) had reduction in IgG and neutralizing antibody levels, respectively, during the early convalescent phase, as compared to 96.8% (30/31) and 62.2% (23/37) of symptomatic patients. Forty percent of asymptomatic individuals became seronegative and 12.9% of the symptomatic group became negative for IgG in the early convalescent phase. In addition, asymptomatic individuals exhibited lower levels of 18 proand anti-inflammatory cytokines. These data suggest that asymptomatic individuals had a weaker immune response to SARS-CoV-2 infection. The reduction in IgG and neutralizing antibody levels in the early convalescent phase might have implications for immunity strategy and serological surveys.As of May 24, 2020, the coronavirus disease 2019 (COVID-19) pandemic, caused by SARS-CoV-2, has affected more than 5 million people around the world. Most patients with SARS-CoV-2 infections have reportedly had mild to severe respiratory illness with symptoms such as fever, cough and shortness of breath, which might appear 2-14 d after exposure. However, there are other patients who are diagnosed by a positive RT-PCR test but are either asymptomatic or minimally symptomatic 2-6 . Increasing evidence has shown that asymptomatic individuals can spread the virus efficiently, and the emergence of these silent spreaders of SARS-CoV-2 has caused difficulties in the control of the epidemic 2,5 . However, our

Viral dynamic modeling of SARS-CoV-2 in non-human primates

“…As pointed out above, this may be due to the fact that we only relied on data in the URT but may also re ect the fact that the infection in NHPs was mild. This is consistent with data obtained in patients with an asymptomatic infection, in which the immune response and the cytokine response remained low throughout the infection period 20 .…”

“…Indeed, we found that the viral load measured on nasopharyngeal swabs peaked at day 4 (CI 95% = [2.2-8.7]) post infection, which is similar to results found in prospective cohorts of asymptomatic or mild infections 24 . Interestingly, the predicted duration of viral shedding was 10.4 days (CI 95% = [8.9-16.6]), remarkably in line with estimates of 9 days 25 and 12 days 9 , but lower than other estimates of about 20 days 20,24 . Moreover, we could use the model to predict the course of infectious virus.…”

The Trans-omics Landscape of COVID-19

“…2a and 4e). However, consistent with a recent report 44 , secretion of in ammatory cytokines such as IL-6, IL-8, IL-2R, and IL-10 was extremely low in sera from the asymptomatic population ( Fig. 4f).…”

“…Asymptomatic patients have drawn great attention as these silent spreaders are hard to identify and cause di culties in epidemic control 44 . Through our study, we observed an unexpected expression discordance exist with extreme transcriptional activation but low in ammatory cytokines secretion in asymptomatic patients.…”

Age is not the only risk factor in COVID-19: the role of comorbidities and of long staying in residential care homes.

“…Moreover they demonstrated that replication of SARS CoV is enhanced in aged mice compared to younger and enhanced viral replication is accompanied by evidence of clinical illness, alveolar damage, and interstitial pneumonitis 22 . Besides to be stroked by a more severe disease, median duration of viral shedding in our very elderly patients is higher compared to that recently reported in younger and symptomatic (14 days) or asymptomatic patients (19 days) 23 and there is a statistically difference between the two groups. This also affects the length of the stay (LOS) in the hospital which result higher in Very Elderly.…”