A health ministry panel on Thursday approved two COVID-19 vaccines developed by Moderna Inc. and AstraZeneca Plc, clearing the way for Japan to boost supplies and speed up its sluggish inoculation program.

The ministry is expected to give the formal green light for use in people aged 18 or older on Friday, bringing the number of vaccines available in the country to three, including the one already in use from Pfizer Inc.

The Moderna vaccine is slated to be used at mass vaccination centers run by the Self-Defense Forces in Tokyo and Osaka as well as similar facilities being set up by some prefectures, while sources said the AstraZeneca one may be stockpiled for later use.

Photo shows bottles of COVID-19 vaccine developed by AstraZeneca Plc and the University of Oxford. (Photo courtesy of AstraZeneca)(Kyodo)

Prime Minister Yoshihide Suga told reporters vaccines are an "ace in the hole" in the fight against the coronavirus pandemic and that he hopes to deliver them to as many people as possible, as quickly as possible.

Japan's vaccine rollout has lagged behind other developed countries. Since its launch in February, first with health care workers and later people aged 65 or older, only around 4 percent of its population of 126 million has received at least one dose.

Suga, whose public support has fallen amid dissatisfaction with his COVID-19 response, has vowed to ramp up inoculations to 1 million shots a day and finish vaccinating the elderly by the end of July.

But a recent government survey showed 14 percent of municipalities expect to miss that deadline amid a dearth of doctors and nurses to administer shots. The effort has also been hampered by technical issues with reservation systems.

The Ministry of Health, Labor and Welfare has a supply agreement to receive 50 million doses from Moderna by September, to be imported and distributed by the U.S. biotechnology firm's Japanese partner Takeda Pharmaceutical Co.

The vaccine must be stored in deep freezers at around minus 20 C, with shots to be administered four weeks apart.

AstraZeneca is contracted to provide 120 million doses, which can be kept at 2 to 8 C and are therefore easier to handle. Its efficacy rate of 76 percent, however, is lower than 94 percent for Moderna and 95 percent for Pfizer.

The first batch of Moderna Inc.'s COVID-19 vaccine to arrive in Japan is unloaded from an airplane at Kansai airport in Osaka Prefecture on April 30, 2021. (Kyodo)

Some countries have also temporarily suspended use of the AstraZeneca vaccine, developed by the British drugmaker with the University of Oxford, or restricted its use in younger people following rare reports of blood clots.

The government is not in a rush to use the AstraZeneca vaccine because it expects to be able to cover everyone aged 16 or older with the Pfizer and Moderna ones, and may choose to store it away for later use, according to the sources. Japan has supply agreements with Pfizer for a total of 194 million doses.

Meanwhile, Chief Cabinet Secretary Katsunobu Kato told a press conference Thursday he is launching a team within the Cabinet Secretariat to consider ways, in coordination with the health and foreign ministries, to certify and allow people who have been inoculated against COVID-19 to travel internationally.

Such "vaccine passports" are being introduced in the European Union and China among other places as a way to gradually allow people to resume business trips and take holidays overseas.

Issues to be addressed by the team include how long the vaccines remain effective and ways to prevent discrimination against people who cannot be inoculated for reasons such as potential allergic reaction.