Metro Manila (CNN Philippines, February 6) — Millions of children remain unvaccinated against measles, flu and other diseases, mostly due to their parent's fear of another Dengvaxia mess, a Department of Health (DOH) official said.

Dr. Ruby Constantino, DOH Disease Prevention and Control Bureau Director said they were not able to include all children in their immunization coverage program since some parents' are apprehensive of its adverse effects, similar to the controversial dengue immunization program in 2014.

Constantino said they gathered this data through focus-group discussions in different cities across Metro Manila.

"The major reason, wherein we have a big drop from 70% in 2017, we had only 39% (coverage) in 2018, of course because of the Dengvaxia scare," Constantino told CNN Philippines' New Day.

President Duterte and the Health Department are urging parents to have their kids vaccinated to avoid getting the flu and other diseases. Also, what are the dangers of swimming in Manila Bay? | #CNNPHNewDay https://t.co/sDo55hwVGt pic.twitter.com/xABKTGRT7a — CNN Philippines (@cnnphilippines) February 5, 2019

In 2018, the DOH sought to include 2.8 million children in their immunization campaign specifically for measles. However, they were only able to vaccinate around one million children or about 44% of their target. In total, 2.4 million children have not received measles vaccinations, Constantino said.

This could result in another measles outbreak in 2019, the health official warned. DOH records showed confirmed measles cases rose by 547 percent from 791 patients in 2017 to 5,120 cases 2018.

Most of the infections in 2018 were recorded in Metro Manila with 1,094 cases, the Autonomous Region in Muslim Mindanao with 645 cases and CALABARZON with 621 cases.

On the other hand, cases of influenza or flu dropped significantly the previous year, Constantino said.

"Based on last year, the last week — December 23 to 31 — we only have 197 cases and these are based on our data, which is actually 84% lower than that of the 2017 of the same period,"she said.

However, she clarified that the data only covered those who sought consultations in hospitals.

The health official said they plan to coordinate with local officials to encourage more parents to have their children vaccinated.

"We are changing our strategies and (we're) being more aggressive and directing our communication not only to parents but to local leaders so they can help us motivate the parents to submit their children to vaccination," she said.

In January 29, President Rodrigo Duterte allayed fears of vaccines and urged parents to have their children vaccinated. He said parents should not be complacent when it comes to protecting their children's health.

READ: Duterte urges parents to have their children vaccinated