According to experts, Vietnam is entering the peak of the epidemic season. Rainy and humid weather creates conditions for disease-transmitting mosquitoes to develop, causing the number of cases to continue to increase in the near future.
Epidemics no longer follow old rules
MSc.BS Vo Hai Son - Deputy Director of the Department of Disease Prevention (Ministry of Health) - said that dengue fever is showing increasingly unpredictable developments when it no longer follows the familiar seasonal rules.
If previously the epidemic usually decreased gradually in the last months of the year, in 2025, the number of cases continued to remain at a high level in November and December. Stepping into 2026, the epidemic continued to increase sharply from the beginning of the year, completely contrary to the trend of many previous years. "Dengue fever is still one of the infectious diseases with the highest number of cases in Vietnam, with hundreds of thousands of cases recorded each year. Previously, the epidemic usually breaks out every 3 years, but in recent years the gap between major epidemics is tending to shorten" - Mr. Son said. The most recent peak epidemic occurred in 2022 with about 371,000 cases nationwide. In the remaining years, the average number of cases is about 150,000 cases/year. This shows that dengue fever epidemics are increasingly difficult to predict and control. Not only in Vietnam, dengue fever is a serious health challenge globally. According to WHO, the number of cases has increased 10 times in the period 2010-2019, putting this disease into the group of major threats to public health. In Vietnam, the epidemic has appeared in most provinces and cities. Notably, many northern localities - where previously only sporadic cases were recorded - are now witnessing a rapid increase in the number of patients, showing that the scope of the epidemic's impact is increasing.
New outbreaks appear in Hanoi
In Hanoi, the number of dengue fever cases continues to increase along with the appearance of new outbreaks. According to the Hanoi Center for Disease Control (CDC), from June 5 to June 12, the city recorded 34 cases in 21 wards and communes, an increase of 8 cases compared to the previous week. A new outbreak appeared in Thanh Oai commune during the week. Since the beginning of 2026, Hanoi has recorded 337 cases in 93 wards and communes, higher than the same period last year. The city has not recorded any deaths, but 7 outbreaks have appeared, including one active outbreak. The continuous recording of new cases and the appearance of new outbreaks shows the risk of the epidemic spreading in the coming months, especially as the rainy season is approaching. Experts also warn that the dominant circulation of the DENV-2 virus strain - a virus strain associated with a higher risk of progression - may increase the number of complications and create more pressure on the health system. According to MSc. Dr. Vo Hai Son, dengue fever is still circulating in many localities, especially in the South and densely populated urban areas. "The risk of getting the disease can appear right in each person's daily living environment. Dengue fever is not a mild disease. Some cases can progress very quickly, causing shock, severe bleeding, organ failure and death if not detected and treated promptly" - Mr. Son warned.
Ms. Angela Pratt - WHO Chief Representative in Vietnam - said that three main factors are changing the epidemiological picture of dengue fever, including climate change creating conditions for Aedes aegypti mosquitoes to develop, rapid urbanization with unsynchronized infrastructure and increasingly unpredictable epidemic developments. These are also challenges that make dengue fever prevention and control work more complicated in the coming years.
