Vietnam flags polio threat as Laos reports mutated virus near border

Laos recently confirmed its first case of circulating vaccine-derived poliovirus type 1 (cVDPV1) in Savannakhet Province, about 100 km from Vietnam's border, prompting authorities there to declare an outbreak and step up surveillance nationwide, officials said at a national health conference in Hanoi.

Vu Huong, a World Health Organization (WHO) expert, said recent polio outbreaks in the region have been linked to genetically mutated poliovirus strains, including in Indonesia, Papua New Guinea and Laos.

Indonesia recorded six cases between 2022 and 2024, leading to five supplementary immunization campaigns reaching more than 32 million children, Huong said. 

Papua New Guinea detected the virus through environmental surveillance in April 2025 and later recorded 72 cases, triggering large-scale vaccination efforts.

Huong said the situation in Laos poses particular concern for Vietnam due to frequent cross-border travel for trade, tourism and labor. 

He said Vietnam's polio immunization coverage has fallen short of targets in recent years, with coverage for oral polio vaccine at 73 percent in 2024 and injectable polio vaccine at 86 percent, below the 95 percent threshold needed for community immunity.

Vietnam's Expanded Program on Immunization has identified eight high-risk provinces bordering Laos, including Thanh Hoa, Nghe An, Ha Tinh, Son La, Dien Bien, Quang Tri, Quang Ngai, and Dak Lak, officials said.

Pham Quang Thai of the National Institute of Hygiene and Epidemiology said local authorities must urgently raise vaccination coverage to at least 95 percent and administer catch-up doses, particularly in border and high-risk areas.

Vietnam's health ministry said it is coordinating closely with the WHO to monitor developments and prepare response measures. 

The WHO and the Global Polio Eradication Initiative have said they are ready to support Vietnam with vaccines and funding if emergency immunization ampaigns are required.