MANILA, Philippines — While the Philippine government wants everyone to have access to COVID-19 vaccines, immunization won't be mandatory as only half of the population needs to be vaccinated to achieve herd immunity, Malacañang said Monday.

The World Health Organization defines herd immunity as a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached.

"According to DOH (Department of Health), we need to give vaccines to 50% of the population so we can have herd (immunity). To those who do not want to be immunized, we will just let them be," presidential spokesman Harry Roque said at a press briefing. 

Roque noted that 66% of Filipinos are willing to be immunized from COVID-19 based on a recent survey by the Social Weather Stations.

The Duterte administration, Roque added, would borrow money from the Land Bank, Development Bank of the Philippines, and multilateral lenders World Bank and Asian Development Bank to ensure that it has enough funds to buy vaccines. 

At the same briefing, Roque shrugged off reports that Sen. Panfilo Lacson and House Majority Leader Martin Romualdez have received COVID-19 vaccines. 

"That's what the president said. We will spend for the vaccines of the poor, our frontliners, our soldiers, and our policemen. The government will buy (the vaccines to be given to them)," the Palace spokesman said. 

"If there are people who have been vaccinated, that did not come from the government. The assurance of the President is if they were bought by our government, the poorest people would be prioritized," he added.