As many Asian countries battle their worst surge of Covid-19 infections with the rapidly spreading delta variant, the slow flow of vaccine doses from around the world is finally picking up speed, giving hope that low inoculation rates can increase and help blunt the effect.

With many vaccine pledges still unfulfilled and the rates of infection spiking across multiple countries, however, experts say more needs to be done to help nations struggling with the overflow of patients and shortages of oxygen and other critical supplies.

Some 1.5 million doses of the Moderna vaccine were set to arrive Thursday afternoon in Indonesia, which has become a dominant hot spot with a record-high number of infections and deaths.

The U.S. shipment comes in addition to 3 million other American doses that arrived on Sunday, and 11.7 million doses of AstraZeneca that have come in batches since March through the U.N.-backed COVAX mechanism, the last earlier this week.

“It’s quite encouraging,” said Sowmya Kadandale, health chief in Indonesia of UNICEF, which is in charge of the distribution of vaccines provided through COVAX. “It seems now to be, and not just in Indonesia, a race between the vaccines and the variants, and I hope we win that race.”

Many, including the World Health Organization, have been critical of the vaccine inequalities in the world, pointing out that many wealthy nations have more than half of their populations at least partially vaccinated, while the vast majority of people in lower-income countries are still waiting on a first dose.

The International Red Cross warned this week of a “widening global vaccine divide” and said wealthy countries needed to increase the pace of following through on their pledges.

Vietnam, Thailand, and South Korea have all imposed new lockdown restrictions over the past week as they struggle to contain rapidly rising infections amid sluggish vaccination campaigns.

In South Korea — widely praised for its initial response to the pandemic that included extensive testing and contact tracing — a shortage in vaccines has left 70% of the population still waiting for their first shot.

Thailand, which only started its mass vaccination in early June, is seeing skyrocketing cases and record deaths, and only about 15% of people have had at least one shot. In Vietnam, only about 4% have.

Many other countries in the region have vaccination rates

for a variety of reasons, including production and distribution issues as well as an initial wait-and-see attitude from many early on when numbers were low and there was less of a sense of urgency.

Some were shocked into action after witnessing the devastation in India in April and May as the country’s health system collapsed under a severe spike in cases that caught the government unprepared and led to mass fatalities.

At the same time, India — a major regional producer of vaccines — stopped exporting doses so that it could focus on its own suffering population.

(With AP inputs)