WATCH: Senate to open probe on the Dengvaxia vaccine controversy on Monday #ANCRecap pic.twitter.com/ptYDSvpKfl

— ABS-CBN News Channel (@ANCALERTS) December 10, 2017

MANILA - Former President Benigno Aquino III will be invited to the Senate probe into the controversial dengue vaccine program that was initiated during his term.

Senator Richard Gordon, chairman of the Blue Ribbon Committee, said Aquino has to explain the meetings he had with officials of French pharmaceutical giant Sanofi Pasteur.

Sanofi is the maker of the controversial dengue vaccine Dengvaxia used in the program of the Aquino administration, which has spurred a health scare in the country.

"Eventually, he will be invited because it's already a fact. It's already public knowledge that he met twice [with Sanofi officials]," Gordon told ANC on Sunday.

The senator added that after the said meeting, the process in the purchase of Dengvaxia was fast-tracked. The government spent P3.5 billion in the procurement of the vaccines.

• TIMELINE: The Philippines' dengue vaccine program

Government data show the vaccine has been given to about 830,000 children in Metro Manila, Southern Luzon, Central Luzon and Central Visayas, as of November.

"He was extremely excited about the prospects in that meeting. And after the meeting in Paris, it became really... greasing the tracks, so to speak. Bumilis ang takbo ng proseso," he said.

Sanofi earlier revealed that its dengue vaccine may cause more severe symptoms on those who had not been previously infected by the mosquito-borne disease.

This prompted the Health Department to suspend the dengue vaccination program in the Philippines. Sanofi has since clarified that the potential cases of "severe dengue" would not be fatal.

The Senate is set to open the hearing on the controversial dengue vaccines on Monday. The focus of the proceeding will be on public safety and the process of procurement of the vaccines.

• READ: Senate set to tackle DOH procurement of dengue vaccine