The region escaped the worst when the pandemic erupted last year, but in recent weeks has seen the highest deaths globally, as soaring infections push fragile healthcare systems to the brink and expose sluggish vaccination rollouts.

"This Covid-19 surge driven by the Delta variant is claiming a tragic toll on families across Southeast Asia and it's far from over," Alexander Matheou, Asia Pacific Director, International Federation of Red Cross and Red Crescent Societies, said in a statement.

It noted that most Southeast Asian countries including Vietnam, Thailand and Indonesia have been posting record Covid-19 infections or fatalities.

Indonesia reported 1,128 fatalities, down from its worst levels above 2,000 late last month, but still the highest daily death toll for any country in the world.

Yet while countries like Canada, Spain and Britain have fully vaccinated more than 60 percent of their people, and the United States more than 50 percent, Southeast Asian countries are well behind, according to a Reuters Covid-19 tracker.

By contrast, Indonesia and Philippines, the most populous countries in Southeast Asia, have only fully vaccinated around 10-12 percent of their people, while Vietnam sits at below 2 percent.

"In the short-term, we need much greater efforts by richer countries to urgently share their millions of excess vaccine doses with countries in Southeast Asia," said Matheou, adding that vaccine companies and governments also needed to share technology and boost production.

"These coming weeks are critical for scaling up treatment, testing and vaccinations, in every corner of all countries in Southeast Asia," he said, adding that there must be a target for vaccination rates of 70-80 percent.