TOKYO >> Japan on Sunday formally approved its first COVID-19 vaccine and said it would start nationwide inoculations within days, but months behind the U.S. and many other countries.

Japan’s health ministry said it had approved the vaccine co-developed and supplied by Pfizer Inc.

The announcement comes after a government panel on Friday confirmed that final results of clinical testing done in Japan showed that the vaccine had an efficacy similar to what overseas tests showed.

Many countries began vaccinating their citizens late last year, and Pfizer’s vaccine has been used elsewhere since December.

Under the current plan, about 20,000 front-line medical workers at hospitals in Japan will get their first shots beginning around Wednesday. About 3.7 million other medical workers will be next, followed by elderly people, who are expected to get their shots in April. By June, it’s expected that all others will be eligible.

Health ministry official Yuta Yamashita said inoculations can start as soon as a ministry panel on vaccination logistics gives the go-ahead.

The approval was granted in a special fast-track process for emergency use. It took two months compared to the usual one year in a country known for cautious and slow-moving approval processes.

Still, the rollout in Japan is months behind many other countries because the government had asked for clinical testing at home in addition to the multinational tests Pfizer conducted on more than 40,000 people from July to November. Many countries accepted Pfizer’s results and moved ahead.

In a country where many people are skeptical about vaccines, Japan sought additional tests to address safety concerns. But the tests were conducted on only 160 people, and some question whether it was worth it to delay the rollout.

Vaccines are considered key to holding the delayed Tokyo Olympics this summer. Japan is expected to receive 144 million doses from Pfizer, 120 million from AstraZeneca and about 50 million from Moderna before the end of this year, enough to cover its population.

Vaccines being developed by Japan are still in the early stages, so the country must rely on imports. AstraZeneca applied for approval in Japan only recently, while Moderna hasn’t applied yet. Japan’s reliance on the imports, many of them subject to EU export controls, is also causing concerns about supplies.

Shigeru Omi, the head of the government coronavirus task force, earlier this month cited a lack of global competitiveness of Japanese pharmaceuticals as a reason for the delayed rollout.