Even a single dose of CYD-TDV (Dengvaxia) can provide lasting protection against more severe forms of dengue

Dengue is a significant public health challenge in tropical regions, such as the Philippines.

In 2017, the Philippine Department of Health began giving a dengue vaccine called CYD-TDV (Dengvaxia) to children aged 9–14 in Cebu province. However, the program stopped after just one dose due to concerns about safety in seronegative individuals. This left many children, particularly in Cebu province, with only a single dose of the three-dose vaccine regimen. Earlier studies up to 2020 showed that a single dose provided some protection against dengue, but the long-term effect was unclear.

From February 2018 to February 2023, researchers studied children in Cebu who were eligible for the 2017 vaccination and were later hospitalized with suspected dengue. Blood tests confirmed dengue infection, and cases were classified based on severity: regular dengue, dengue with warning signs (like persistent vomiting, bleeding, or severe abdominal pain), and severe dengue. For comparison, healthy children from the same neighborhoods and age groups were also included. Out of 584 confirmed dengue cases, most (68%) had warning signs, 1% developed severe dengue, and one child died. Dengue virus type 3 was the most common strain detected.

Results showed that one dose of CYD-TDV gave 21% protection against hospitalization from dengue overall, but 31% protection against more severe cases. While the study could not confirm participants’ dengue exposure history before vaccination, most were likely previously exposed. The findings suggest that even a single dose of CYD-TDV can offer lasting protection against more serious forms of dengue in areas where the virus is common.

This study provides a comprehensive evaluation of the five-year effectiveness of a single dose of CYD-TDV against hospitalized virologically confirmed dengue (VCD) in a dengue-endemic setting. Despite limitations, including the absence of baseline serostatus data and disruptions caused by the COVID-19 pandemic, the findings reveal that a single dose offers 21% overall effectiveness against hospitalized VCD, with higher protection observed within the first year post-vaccination (49%). Importantly, as mentioned, the vaccine demonstrated 31% effectiveness against more severe forms of dengue, including cases with warning signs and severe dengue, over the five years. These results highlight the durability of partial protection in the context of an incomplete vaccination schedule, albeit with evidence of waning effectiveness over time.

Authors: Kristal An Agrupis (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila), Maria Vinna Crisostomo (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila), Jedas Veronica Daag (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila), Jesus Sarol Jr. (Interdisciplinary Health Sciences Institute, University of Illinois at Urbana-Champaign), March Helena Jane Lopez (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila), Kiarah Louise Florendo (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila), Clarissa de Guzman (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila), Ava Kristy Sy (Department of Virology, Research Institute for Tropical Medicine, Muntinlupa), Zoraida Yurango (Cebu Provincial Hospital – Bogo, Bogo City, Cebu), Olivia Dandan (Cebu Provincial Hospital – Balamban, Balamban, Cebu), Jean Balabat (Eversley Childs Sanitarium and General Hospital, Mandaue City, Cebu), Jacqueline Deen (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila), and Michelle Ylade (Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila)

Read the full paper: https://doi.org/10.1016/j.vaccine.2025.127142