TOKYO (AP) — Japanese Prime Minister Fumio Kishida spoke by phone with Pfizer Inc. CEO Albert Burla on Friday, apparently to ensure a fast supply of COVID-19 vaccines for booster shots amid the global spread of the omicron variant of the coronavirus.

Japan, which lacks home-developed vaccines, has so far approved booster shots from U.S. pharmaceutical companies Pfizer and Moderna Inc. Japan is moving to shorten the interval between second jabs and boosters from eight months to six amid a global upsurge in cases and fears of more community transmissions at home.

Kishida was believed to have asked Burla to speed up the supply schedule accordingly.

Chief Cabinet Secretary Hirokazu Matsuno confirmed the talks between Kishida and Burla but declined to give further details. He said the prime minister planned to explain vaccination plans later Friday.

Matsuno told reporters Japan has signed deals with Pfizer and Moderna for a combined 170 million doses as booster shots, which he said would be “enough to cover necessary doses.”

Japan on Dec. 1 started giving booster shots to medical workers using the Pfizer vaccine, with elderly people expected to be next in line. The Health Ministry on Thursday granted fast-track approval for the Moderna vaccine to be used in booster shots. Japan already uses both, as well as the AstraZeneca vaccine, for the first two shots.

Kishida’s talks with the Pfizer CEO come amid growing concerns over a possible rise in community transmission of the omicron variant in Japan.

Tokyo on Thursday confirmed its first case of the omicron variant in a traveler from the United States who was isolating at home. Her male friend whom she saw shortly after arrival has since tested positive for COVID-19 after attending a soccer game. The man's samples are still being analyzed to determine the variant.

Separately, the Health Ministry announced Thursday that one of its quarantine officials tested positive for the omicron variant. The new findings bring Japan’s confirmed omicron cases to 34.

Japan’s government says all omicron cases so far have been detected by its border controls, but experts say it is only a matter of time before community transmission cases start surfacing.

Japan has stepped up its border controls since the omicron variant was first reported in South Africa, and now bans entry to most foreign nationals. Japan has had about 1.73 million cases since the pandemic began, with about 18,400 deaths.