As some people fear a second wave, and the toll of novel coronavirus infections is increasing in Beijing, China, searchers keep on working on this virus that keeps on spreading. Many wishes to know more about immunity. On June 18, several Asian searchers disclosed the background of a new study released in Nature Medicine. According to it, cases infected by Covid-19 that are asymptomatic may show a lower antibody rate than people who developed symptoms.
To confirm these hypotheses, searchers work on 37 asymptomatic cases which infection has been confirmed by a virologic test before April 10, 2020 in the Wanzhou district. Among these 37 asymptomatic cases, the study included 22 females and 15 males with ages ranking from 8 to 75 years.
When being isolated at the hospital, searchers noticed that patients had a median 19-day virus shedding, against 14 days in the 37 patients showing symptoms (fever, cough, shortness of breath…). Then, eight weeks after being discharged from the hospital, neutralizing antibody levels – said to enable immunity against the virus – dropped down by 81.1% in asymptomatic cases, against 62.2% in symptomatic cases.
“In this study, we observed that IgG levels and neutralizing antibodies in a high proportion of individuals who recovered from SARS-CoV-2 infection start to decrease within 2–3 months after infection.” they write.