Parents of 700,000 children immunized under a government dengue vaccine campaign are mulling whether to file a class suit against French drug-maker Sanofi Pasteur for exposing them to health risks.

Parent representative Ernesto Francisco, Jr. on Dec. 5 said a class suit against the pharmaceutical firm would ensure funds for medical expenses if children suffer adverse effects of the dengue vaccine Dengvaxia.

The Philippine government last week suspended the US$68-million dengue immunization drive after Sanofi disclosed its vaccine could, in some cases, worsen the disease.

"We are stopping the program until we can get recommendations from the WHO [World Health Organization]," Health Secretary Francisco Duque III said Dec. 1.

The Food and Drug Administration also ordered the drug-maker to remove the vaccine from the local market.

Philippine clergy, meanwhile, used the controversy to step up their warnings against the use of artificial contraceptives.

Dengue fever is a mosquito-borne viral infection that can cause severe flu-like symptoms, which can prove deadly in some cases.

The government rolled out the vaccine before the WHO published a position paper on its use and risks, according to the agency's Philippine office.

The administration of former Philippine president Benigno Aquino gave Dengvaxia the green light in 2015.

It launched the vaccination drive for public elementary school students at the start of 2016, despite warnings of premature use and a lack of transparency in studies on its effects.

The WHO had asked the government to consider using the vaccine only "in areas where at least 70% of the community had already been exposed to the virus," and only for people aged nine years old and over.

In April 2016, WHO acknowledged the government's pilot areas met the exposure criteria.

It published its position paper more than six months after the government approved the vaccine.

However, "The WHO position paper did not include a recommendation to countries to introduce the dengue vaccine into their national immunization programs," the world health body's country office said in a statement.

Sanofi last month stunned the immunization market with the disclosure that its vaccine could increase risks of "severe dengue" in people who have not contracted the disease before.

A statement by the company on Dec. 5 said the complications would not be fatal.