At least 861 suspected cases of measles have been reported as of 2 February, the Department of Health said on Wednesday.
Some 50 people - mostly children - are believed to have died from the disease, officials told local media.
Authorities say more than two million unvaccinated children are at risk.
Health secretary Francisco Duque told local media that bronchopneumonia from measles complications can be deadly, and encouraged parents to bring their children for immunisation.
"Parents should not wait for complications to set in because it might be too late," he said.
People in the Philippines have been reluctant to have their children immunised at government health centres, after complications related to a dengue vaccine, Dengvaxia.
Measles is a highly contagious airborne disease which spreads easily through coughs and sneezes. Initial symptoms usually include a fever, cough, runny nose and inflamed eyes. A red rash appears on the face and body a few days later.
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