The Zika Comeback: One Vaccine, One Hope

Asia, the epicenter of flaviviruses like Japanese encephalitis (JE), dengue, and Zika, faces both a critical need and a strategic opportunity to lead vaccine development. Phylogenetic evidence shows that the Zika strain behind the Americas outbreak originated in Southeast Asia. With global pipelines favouring high-income markets, regional biotech can drive preventive solutions, scale production, and avert outbreaks as Zika quietly resurfaces across Southeast Asia.

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Nearly a decade after the world's attention was gripped by the Zika virus outbreak in Brazil, the disease is quietly making a comeback in Asia. In recent years, clusters of infections have been reported in Singapore, imported cases traced back to Bali have been identified in South Korea, and other sporadic outbreaks have been recorded across Southeast Asia.

In 2023, 758 Zika cases were reported in Thailand, up from 190 in 2022, reflecting a surge of over 300 per cent. Among them were 33 women and 15 newborns presenting with Zika and congenital Zika syndrome respectively. Singapore reported 15 cases of Zika in the same year. In 2025, the Singapore's National Environment Agency reported two cases in June, while Thailand's Ministry of Public Health issued a warning in July about an increase in Zika cases across three Thai provinces including Bangkok

While the numbers remain relatively small compared to dengue or malaria, the reappearance of Zika is concerning. It underscores how climate change, rising temperatures, and frequent flooding are enabling Aedes mosquitoes to thrive, increasing the risk of mosquito-borne infections in the region.

The urgency: Asia's resurgent threat

For many, Zika is associated with the outbreak around the 2016 Olympic Games in Brazil and feels like something that happened long ago and far away. But what most people don't know is that there is phylogenetic evidence that the strain of Zika virus that caused the serious outbreak of the disease in Brazil and the Americas had its origin in Southeast Asia.

Although first isolated in a sentinel monkey in the Zika Forest in Uganda in 1947, serological studies published in the 1950s and 1960s showed that there was already a wide geographic footprint for Zika virus in Southeast Asia, ranging from Pakistan to the Philippines; which is why public health experts warn that Asia cannot afford to be complacent.