Photo/Illutration A computer rendering of the COVID-19 virus by the U.S. Centers for Disease Control and Prevention (CDC/ Alissa Eckert, MS; Dan Higgins, MAMS)

Eight individuals who tested positive for coronavirus antibodies developed immunity against the virus, the first such confirmation in Japan, the health ministry said July 14.

Health authorities will now try to assess how long immunity will last and how to use the antibody testing results in the coming months.

Antibodies are protective proteins made in response to an infection and act against it.

The antibody testing was done in Tokyo, Osaka and Miyagi prefectures in June, and involved about 8,000 people.

Only eight people produced positive readings for coronavirus antibodies twice when the 8,000 were tested using two kits produced by separate manufacturers. The kits not only detect the existence of antibodies, but also determine the amount in a person’s body.

The tests confirmed the eight people have antibodies that can neutralize the virus and prevent reinfection, according to the ministry.

Some people only tested positive under one of the testing regimes, suggesting they were false positives. Others were found to have levels of antibodies just below the threshold for a positive diagnosis.

In all, the number of those people came to 300 or so. But health technicians could not confirm that one person among them had developed immunity.