Epidemiology and Genotype Dynamics of Dengue in Hospitalized Patients in Northern Vietnam Between 2020 and 2022.

Background: Arboviruses, including Dengue (DENV), Zika, and chikungunya, cause recurrent outbreaks of varying intensity in tropical countries. This study aimed to investigate other arboviruses, including Zika and chikungunya, in patients clinically suspected of Dengue and to characterize the circulating Dengue serotypes and genotypes in Northern Vietnam from 2020 to 2022. To date, information on this topic in the region has been limited. Methods: Multiplex real-time polymerase chain reaction (PCR) was used to detect Dengue, Zika, and chikungunya RNA, and DENV serotypes were identified via real-time reverse transcriptase PCR from 426 clinically Dengue suspected patients. Patients were screened for NS1 antigen and anti-DENV immunoglobulin (Ig) G/IgM antibodies. Phylogenetic analysis of DENV Capsid-premembrane gene sequences was performed to investigate genotype distribution. Results: Dengue was confirmed in 95% of cases, with no Zika or chikungunya RNA detected. DENV-2 was the predominant serotype (61%), followed by DENV-1 (31%) and DENV-4 (7%). Coinfections were observed, with DENV-1 and DENV-2 being the most common. In 2022, a high incidence of Dengue cases with warning signs and severe Dengue was observed, accompanied by elevated liver enzyme levels and reduced platelet counts. Phylogenetic analysis revealed that the DENV-1 and DENV-4 serotypes clustered with previously reported regional virus, while DENV-2 showed a shift from genotype Asian I to Cosmopolitan over the study period. Conclusions: This study underscores a significant rise in Dengue severity and shifts in DENV genotypes in recent years in Northern Vietnam, emphasizing the importance of understanding genotype dynamics and clinical dynamics for improving outbreak preparedness and response strategies.