MANILA - Former president Benigno Aquino III joined Thursday a Senate investigation into his administration's dengue vaccination program that is now at the center of a health scare.

The Senate Blue Ribbon Committee invited Aquino to its hearing to shed light on the procurement of the vaccine Dengvaxia after manufacturer Sanofi Pasteur admitted that it may cause "more cases of severe disease" if given to those who have not had the mosquito-borne illness before.

Aquino will be asked to explain his 2 meetings with Sanofi officials before the program's approval, said Senator JV Ejercito, chair of the Senate health committee.

"Hindi naman ito kuwestyon whether legal o hindi; more on ethical ba ito o hindi," he told DZMM ahead of the 10 a.m. Senate hearing.

Dating Pangulong Aquino, dumating na sa Senado at dumiretso sa tanggapan ni Sen. @bamaquino kulang-kulang 1 oras bago ang nakatakdang pagdinig ng Senate Blue Ribbon Committee pic.twitter.com/lLz1b44Dwr | @ZandroDZMM

— DZMM TeleRadyo (@DZMMTeleRadyo) December 14, 2017

Some 730,000 public school students received Dengvaxia under the Aquino government's immunization program, which was suspended earlier this month.

• Philippines suspends dengue vaccine program after Sanofi warns of risks

The Philippines was the first country in Asia to approve the vaccine for individuals aged 9 to 45 years old in December 2015.

The government procured P3.4 billion worth of Dengvaxia intended for 1 million public school children in areas reported to have the highest incidence of dengue in 2015: in Metro Manila, Central Luzon, and CALABARZON regions.

The vaccine was to be administered in 3 phases at 6-month intervals beginning April 2016.

• Officials defied experts' advice in pursuing dengue immunization program

Sanofi has said that only 1 out of 10 Filipinos have no prior history of dengue and are the only ones facing the risk of contracting severe dengue.

• Doctor rips 'downplaying' of Dengvaxia risks

Watch a live streaming of the hearing here.