Coronavirus vaccines Pfizer and AstraZeneca were found to be effective against the highly contagious Delta variant of COVID-19 after two doses, according to a new study.

In a study published by the New England Journal of Medicine on Wednesday, both doses of either the Pfizer or AstraZeneca vaccines help protect against symptoms from both the alpha or delta variants.

The study said that two doses of the Pfizer vaccine was 93.7 percent effective at preventing symptomatic infections from the alpha variant and 88 percent from the delta variant.

Two doses of AstraZeneca, meanwhile, were found to be 74.5 percent effective against alpha infections and 67 percent against delta.

If an individual only received one dose of either vaccine, its effectiveness against alpha variant will only be about 48 percent, and 30 percent against delta, the study pointed out.

"The absolute difference in vaccine effectiveness against symptomatic disease with one dose of vaccine with the delta variant as compared with the alpha variant was approximately 12 to 19 percentage points," the researchers wrote, adding that the differences in vaccine effectiveness after two doses were small.

The researchers said that the findings support efforts to maximize vaccine uptake with two doses among vulnerable populations.

The World Health Organization (WHO) on Wednesday warned that the delta variant is expected to become the dominant strain of the virus over the coming months.

First detected in India, the delta variant of the coronavirus has now been recorded in 124 territories and already accounts for more than three-quarters of sequenced specimens in many major countries, the WHO said.

As of July 21, a total of 35 delta variant cases have so far been detected in the Philippines, including three deaths and 32 recoveries.

President Duterte on Monday, July 19, warned the public that the government is eyeing to reimpose “stricter restrictions” should the delta variant spread further in the country.