Medical researchers say the China coronavirus may be present in patients displaying no outward signs of illness
A new study conducted by Chinese experts found Covid-19 antibodies may start to diminish within two or three months in most asymptomatic and symptomatic patients after they are initially infected, raising doubts over whether antibodies could serve as “immunity passports” for people who have recovered from the illness.
The study published by Nature Medicine on June 18, performed by a team from Chongqing Medical University, also found that asymptomatic people had a weaker immune response to Covid-19 infections than those who had symptoms.
The researchers compared the immune responses of 37 asymptomatic individuals and 37 symptomatic patients and found 40% of the asymptomatic group gave a negative result in a test of blood serum for immunoglobulin G antibodies eight weeks after being discharged from the hospital, while the number for symptomatic group only stood at 12.9%.
The authors said in the paper, “Together, these data might indicate the risks of using COVID-19 ‘immunity passports’ and support the prolongation of public health interventions, including social distancing, hygiene, isolation of high-risk groups and widespread testing.”
No consensus has been made on how long and to what extent antibodies can protect people. The World Health Organization released a scientific briefing in April warning that “there is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection.”
