Duong Thi Hong, deputy director of the National Institute of Hygiene and Epidemiology, said at a meeting Friday that the low vaccination rates could also cause a greater spread of existing diseases.

Vietnam is among several countries where parents are delaying vaccination for their children out of doubts regarding the importance and safety of vaccines, an unnamed World Health Organization (WHO) official was quoted as saying at the meeting.

In 2018 about 87,000 children under a year old [in Vietnam] were not vaccinated. They mainly reside in remote areas, but there are unvaccinated children in urban areas as well, according to WHO figures.

Insufficient knowledge of vaccination schedules, fear of vaccines’ side effects and a desire to "let nature take its course" caused these trends, according to the Ministry of Health.

Ho Chi Minh City reported a surge in measles patients in late 2018 and early this year. The Hospital for Tropical Diseases in Saigon, one of the city’s top public hospitals, was treating 60 to 70 measles patients a day in January, 50 times higher year-on-year.

Hanoi reported 192 measles cases in the first two months this year, compared to 22 cases the same time last year.

The capital city suffered a severe measles outbreak in 2014, which killed at least 133 children. Doctors blamed it on parents not having their children vaccinated.

The Hanoi outbreak also coincided with the deaths of more than 10 babies who had been given the Dutch-made Quinvaxem vaccine between November 2012 and May 2013, and several more when it was reintroduced in October 2013. The Ministry of Health had said the drug was not to blame for the deaths.

Anti-vaccination movements have taken root globally and have been on the rise in recent years, with many countries reporting the return of diseases such as measles and polio, which were thought to have been eradicated or controlled, partly due to these movements.

WHO named vaccine hesitancy as one of the 10 biggest threats to global health in 2019 in a report last January.

"Complacency, inconvenience in accessing vaccines, and lack of confidence are key reasons underlying hesitancy."

The United Nations reported last week that amid slipping global vaccination rates, measles cases rose 300 percent worldwide through the first three months of 2019 compared to the same period last year. 170 countries have reported 112,163 measles cases to WHO, compared to 28,124 cases from 163 countries last year.

In the U.S., 626 cases have been confirmed this year, putting it on track to surpass the record number of measles cases in a single year since the vaccine-preventable disease was declared eliminated in 2000.

Japan had also been experiencing one of its worst measles outbreaks in a decade, with at least 167 new patients reported in 20 prefectures from the beginning of 2019 to February.