The Philippines on Monday started giving second COVID-19 booster doses for immunocompromised adults, joining a growing number Asian countries offering a fourth vaccine shot.

Nearly 61% of the Philippines' 110 million population have been vaccinated, while nearly 13 million people have received first booster doses, government data show.

Of 690,000 people deemed most vulnerable, between 7,000 and 13,000 have been initially targeted for the second round of boosters, to increase protection against COVID and its variants.

"Because of increasing vaccination coverage, while COVID-19 is still there, in the near future we can consider this as an endemic disease," Health Secretary Francisco Duque told a public forum.

Among those that have approved the use of second booster are South Korea, Taiwan and Singapore, which is hoping to prevent a coronavirus resurgence, particularly among its elderly, as it removes most remaining curbs this week.

The Philippines has been cautious with its reopening, despite efforts to revive an economy that contracted more than 9% in 2020, having been one of Asia's fastest growing before the pandemic.

With 3.68 million cases overall and more than 60,000 deaths, the country has suffered one of the worst COVID crises in Southeast Asia, although new daily infections have fallen significantly, now at an average 207 per day, just 1% of the peak, according to a Reuters global data tracker.