MANILA (BLOOMBERG) - The Philippines has shortened the interval for administering Covid-19 vaccine boosters amid the threat of the Omicron variant.

Effective Wednesday (Dec 22), boosters may be given to adults at least three months after the second dose of a primary two-dose vaccine, or two months after a single dose, the Department of Health said.

The agency revised its initial recommendation for a six-month wait time.

"The approval came at an opportune time as several countries also re-strategised in light of the Omicron and other Covid-19 variants that may emerge," Health Secretary Francisco Duque said.

Countries from Germany to Saudi Arabia are moving to accelerate booster shots as the fast-spreading Omicron variant drives surges in different parts of the globe.

In the Philippines, a third case of the Omicron variant was detected from an overseas Filipino from Qatar who arrived in the central province of Cebu on Nov 28.

The Philippines' health department however said that the unvaccinated - especially the elderly and those with underlying medical conditions - should still be prioritised for inoculations.

The South-east Asian nation has fully vaccinated 41 per cent of its population, trailing its neighbours.