Beijing, June 18 (RHC)-- A new study conducted by Chinese and American scientists said that humans may never develop immunity against the coronavirus, the South China Morning Post reported.

The conclusion was based on a non-peer reviewed study looking at whether hospital workers in Wuhan, where the infection was first reported, developed antibodies, after being exposed to the disease.

The report said only 4 percent of the samples studied had developed antibodies as of April. This was based on the assumption that at least a quarter of the more than 23,000 samples tested were infected.

Beijing confirmed 21 new COVID-19 cases as of June 17, China's health authority said on Thursday, down from 31 a day earlier.  Beijing logged its first case in the current outbreak, the worst in the city since early February, on June 11.  The total number of infections has risen to 158 over the past week, according to Reuters news agency.