A landmark nationwide surveillance study by the Indian Council of Medical Research (ICMR) has revealed crucial data on dengue serotypes in India. Conducted through 45 laboratories across 25 states and Union Territories, the analysis of 6,889 lab-confirmed samples demonstrates widespread co-circulation of multiple strains. Consequently, this rising hyperendemicity poses serious clinical challenges for disease severity and upcoming immunization policies.
Prevalence and Distribution of Dengue Serotypes in India
Researchers detected all four serotypes—DENV-1, DENV-2, DENV-3, and DENV-4—simultaneously in eight states, including Maharashtra, Gujarat, Rajasthan, Tamil Nadu, West Bengal, Andhra Pradesh, Haryana, and Madhya Pradesh. Furthermore, fifteen other states reported three circulating serotypes, while two states identified at least two. DENV-2 emerged as the dominant strain nationwide, accounting for 51% of cases. Meanwhile, DENV-3 was responsible for 13%, DENV-1 for 7%, and DENV-4 for 1% of infections. Additionally, regional variations were notable, with DENV-1 causing a higher proportion of cases in Tamil Nadu and Haryana.
Clinical Implications of Concurrent Infections
Approximately 7% of tested patients suffered from concurrent infections involving two or more strains simultaneously. Notably, these co-infections significantly heightened clinical severity. Patients with concurrent infections were more likely to develop severe thrombocytopenia, haemorrhagic manifestations, and severe arthralgia compared to those with single-strain infections. Therefore, continuous molecular surveillance is vital to recognize changing viral dynamics early and guide patient triage.
Impact on Dengue Vaccine Rollout Strategy
As India prepares for a phased dengue vaccine rollout, understanding serotype dynamics becomes paramount. Vaccine efficacy varies across different virus serotypes. Consequently, widespread co-circulation and quasispecies diversity require tailored immunisation strategies to ensure robust multi-strain protection. Moreover, continuous genomic tracking will aid in predicting future outbreaks and optimizing public health interventions.
Frequently Asked Questions
Q1: Why is the co-circulation of multiple dengue serotypes a clinical concern in India?
Co-circulation increases the incidence of concurrent infections with multiple strains. As a result, patients face a higher risk of severe disease manifestations, such as severe bleeding, plasma leakage, and profound thrombocytopenia.
Q2: Which dengue serotype is currently predominant in India?
According to the ICMR surveillance study, DENV-2 is the predominant circulating serotype, representing approximately 51% of analyzed positive samples nationwide.
Q3: How do these surveillance findings influence dengue vaccination strategies?
Because vaccine efficacy varies across different serotypes, detailed surveillance helps health authorities evaluate vaccine candidate performance against prevailing local strains and guide targeted immunization policies.
References
- Ahead of dengue vaccine rollout, all 4 strains found in circulation – ETHealthworld
- Deshpande GRN, Tadkalkar N, Narayan J, et al. Pan-India molecular surveillance of dengue serotypes, 2023–2025. Int J Infect Dis. 2026. PMID: 42323159.
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