MANILA — The Philippines is once again extending a travel ban to keep out the more infectious Delta COVID-19 variant, Malacañang said on Wednesday.

The travel ban, which was set to end on July 15, would stay in place until July 31, said Palace spokesman Harry Roque.

The restriction covers travelers from India, Pakistan, Bangladesh, Sri Lanka, Nepal, United Arab Emirates, and Oman, he said in a press briefing.

Some overseas Filipino workers have been stuck abroad due to the travel ban.

The travel ban exempts repatriation efforts. OFWs who want to come home to the Philippines should contact the embassy or their manning agencies so that mercy flights could be arranged, officials earlier said.

The inter-agency task force on COVID-19 approved last week special commercial flights for countries covered by the travel curbs.

The Philippines has detected among inbound travelers 19 cases of the COVID-19 Delta variant that originated from India, where it unleashed a catastrophic surge in coronavirus infections.

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Governments in Southeast Asia are tightening measures, hoping targeted lockdowns will act as circuit-breakers in arresting record jumps in cases and deaths that started rising in May.

Dicky Budiman, an epidemiologist at Griffith University in Australia, said the region was struggling to cope with the Delta variant and paying for inconsistencies in strategy, messaging, and enforcement of protocols.

He cited the need to broaden the range of vaccines, noting the dominance of the China's Sinovac, owing to its vaccine diplomacy when Western brands were unavailable.

"In handling the pandemic at a bigger scale... vaccines can't stand alone," he said. "Vaccines need to be diversified. Resources need to be diversified."

Indonesia and Thailand on Friday said booster shots with mRNA vaccines would be administered to health workers - most of which were given Chinese vaccines like Sinovac - amid concerns about their resistance to variants.

Thailand said the Pfizer and BioNTech shot would be given to its medical workers, while Indonesia said Moderna vaccines would soon arrive for use among health staff.

Sinovac jabs make up the bulk of the Philippine coronavirus vaccine supply.

Filipino experts are studying the use of mRNA booster shots, the health department said on Monday.

The Philippines has fully vaccinated at least 3.5 million of its 58 to 70 million target population this year.

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Duterte last month urged people to get inoculated and even threatened arrest of vaccine decliners or forcible injection of a drug used on pigs, after data indicated reluctance to be vaccinated or difficulties in making appointments.

The Philippines has in recent years had difficulty in combating mistrust in government-issued vaccines over concern about a dengue vaccine.

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But according to government data, of the first 6.2 million COVID-19 vaccine recipients, only 0.6 percent reported an adverse reaction and only 65 infections were reported among recipients of two doses, with no deaths.

The number of Filipinos willing to get inoculated against the coronavirus rose to 43 percent in June from just 16 percent in February, a Pulse Asia survey showed on Monday, as concerns over the safety of vaccines eased.

With more than 1.47 million infections and over 5,200 deaths, the Philippines has one of the highest coronavirus caseloads in Asia.

— With a report from Reuters