Research in context
Evidence before this study
As of May 1, 2017, no comprehensive reports have described a national response to an outbreak of Zika virus infection in Asia. We searched PubMed up to Feb 25, 2017, for reports published in English with no date limitations using the terms “Zika” and “Asia”, as well as “Zika” and “Singapore”. We identified 51 relevant articles with the first search and 13 with the second. However, these studies were case reports, commentaries, and reviews of what is known about Zika virus in the region. One published report included preliminary phylogenetic analysis of two of the Singaporean outbreak strains, with results suggesting a relation to the Asian Zika virus lineage.
Added value of this study
To our knowledge, this study represents the first comprehensive and multi-faceted analysis of the first Zika virus outbreak in Singapore. The outbreak shows the ease with which the virus can be introduced and spread despite an ongoing national vector control programme. Our results also show evidence of other imported Zika virus strains that did not establish themselves and how the use of measures such as enhanced vector control and community engagement helped to curb incidence within 4 weeks of implementation. We did a phylogenetic analysis of 117 complete and near-complete genomes from the outbreak, which represents a nearly 50% increase in the number of full Zika virus genomes available worldwide.
Implications of the available evidence
The ease of introduction and spread show that outbreaks of Zika virus infection can occur even with baseline vector control. Prompt national action, including targeted vector control, community outreach, and engagement with the media can help to curb the spread of large outbreaks. The implementation of these intensive control measures might be useful for other countries facing the same threat.