TOKYO — Japan’s health ministry started blood tests Monday in three areas including Tokyo in an effort to check what percentage of its people have developed antibodies, a sign of their coronavirus infections in recent past.

The tests will be conducted on 10,000 randomly selected people at age 20 or older from Tokyo and Osaka to represent Japan’s two most-infected prefectures, while Miyagi in the north is one of least infected in the country.

Some 3,000 people will be tested in each area and results will be expected at the end of June.

Japan, due to its lack of testing capability and resources, has until recently begun carefully limiting access to testing mainly to reduce the number of severe cases and fatalities. The strategy, however, has prompted doubts that many people may have been undetected.

Experts say Japan needs to bolster testing to find and isolate patients quickly as it gradually resumes businesses after its seven-week state of emergency ended last week.

Japan has almost 17,000 confirmed cases and nearly 900 deaths, significantly fewer than the U.S. and Europe.

Unlike the nasal swab tests that determine a current infection, an antibody test may show if one had been infected with the coronavirus in the recent past, possibly acquiring some immunity from the virus.

Experts say accuracy levels of antibody tests often vary, while it is still unknown how long any immunity may last. Experts hope results will help the to track how virus spreads in communities.

Yoshiko Nakanishi, a physician at the Japan Anti-Tuberculosis Association that helps in the antibody tests, said it will be useful to find coronavirus infection rates among the Japanese and how results compare within the country and internationally.