MANILA — The Philippines suspended its school-based dengue immunization program on Friday after the French pharmaceutical giant Sanofi warned that its flagship vaccine, Dengvaxia, had been found to pose health risks in people not previously infected.

The suspension came after health experts expressed worries about Sanofi’s announcement this week.

The company said further clinical studies had revealed that, in those who had previously had dengue, the vaccine could prevent repeat infection. But for those who had not had dengue, and were vaccinated and later became infected, “more cases of severe disease could occur,” Sanofi said in the advisory.

With more than 740,000 elementary school students in the Philippines having already received Dengvaxia vaccinations, the government decided to halt the program for the time being.

The Philippine health secretary, Francisco Duque, said the program would be “on hold while review consultations are on the way.” He added that the government would seek help from medical experts outside the Philippines, including from the World Health Organization.