The government will start testing 10,000 people in Tokyo, Osaka and Miyagi prefectures for coronavirus antibodies next month as part of efforts to better understand how it spreads, health minister Katsunobu Kato said Friday.
Authorities hope to get a rough grasp of how many people were infected — including those without symptoms — and to gain insight into infection numbers should there be a resurgence.
The data will also help the government estimate how many people need to be vaccinated.
"We will confirm how much immunity the entire community has acquired and utilize the data to prevent the virus spreading in the future," Kato said at a news conference.
The government selected the three because Tokyo and Osaka have high infection rates in terms of positive tests per 100,000 people, and Miyagi has a relatively low rate.
The blood tests look for specific proteins made by the immune system in response to infection and will be conducted on roughly 3,000 adults randomly selected in each of the prefectures who agree to take part.
Local authorities will conduct the tests and send the blood samples to the central government for analysis. The state will leave it up to the municipalities on whether to inform participants of their results.
The Health, Labor and Welfare Ministry plans to use several methods to detect the antibodies and figure out the amount in the specimens, ministry officials said.
It typically takes one to three weeks to develop coronavirus antibodies once infected, according to the U.S. Centers for Disease Control and Prevention.