Hawaii’s mass COVID-19 immunization sites are putting the brakes on new appointments, at least for the next few weeks, as vaccine supplies remain limited across the country.

Hawaii Pacific Health is currently inoculating 1,850 people a day, less than 50% of total capacity, and will schedule first-dose appointments only after second shots can be secured, President and CEO Ray Vara told the House Select Committee on COVID-19 Economic and Financial Preparedness. Hawaii Pacific Health — parent company of Kapiolani Medical Center for Women & Children, Pali Momi Medical Center, Straub Medical Center and Wilcox Health on Kauai — runs a large-scale vaccination clinic at Hono­lulu’s Pier 2 that can accommodate up to 5,000 people a day.

“It concerns us that we’re going to be limited to mostly doing just second shots and not being able to schedule new appointments for first shots,” Vara said.

“The challenge on a going-forward basis for us, honestly, is making sure that we have adequate vaccine,” he added.

Jill Hoggard Green, president and CEO of The Queen’s Health Systems, which had immunized 43,300 as of Friday, said mass vaccination sites are “making the difference in terms of access for large numbers of people.”

However, the only barrier is getting enough doses in the islands, she said.

Health officials are racing to get shots in arms as the coronavirus rapidly mutates into more contagious strains across the globe. The state Department of Health announced Friday it had found the first case of the highly transmissible COVID-19 variant originally discovered in the United Kingdom. On Saturday a second case was confirmed.

“We are worried at this point for the next three weeks in terms of new appointments,” Green said.

“We’ve actually cut the number of slots we have available. We’ve cut them because we don’t know (whether) we’ll have the second doses for everyone that we bring in,” she added. “We are worried about watching the variants. It’s critical that we get shots in people’s arms. We cannot slow down right now. That’s going to be the most important in terms of reducing pain and suffering from this disease and the most important in terms of opening our economy and our community and reducing that type of pain and suffering.”

The hospitals are hoping another vaccine by Johnson & Johnson will be approved within weeks by the U.S. Food and Drug Administration, “because bringing another vaccine to the system may in fact also really give us more capacity,” Green said.

DOH spokesman Brooks Baehr said the department is managing vaccine supplies to ensure those who have received their first shot will be able to get a second dose on time.

The Health Department anticipates 41,700 doses will arrive in the islands this week.

“Ensuring we have second doses for these people means we will have fewer first doses for other people,” he said. “It’s a matter of mathematics and very complex scheduling at vaccination sites around the state. We would be delighted if we could get 80,000 doses a week. That would go a long way toward speeding up the vaccination program.”

Health officials reported 33 new coronavirus infections, bringing the state’s total since the start of the pandemic to 26,500 cases. However, there were fewer COVID-19 tests conducted over the weekend.

There were no new coronavirus deaths reported, with the statewide death toll remaining at 418.