For dengue patients, fever often subsides or disappears between days 3-7. However, this period remains critical. During this dangerous phase, the dengue virus can increase vascular permeability, leading to plasma leakage, a drop in platelet count, and potentially severe complications such as shock, hemorrhage, liver or kidney failure, myocarditis, respiratory failure, or even multi-organ failure within 24 hours. Initial symptoms, typically experienced in the first one or two days, include fever, headache, eye pain, muscle and joint aches, fatigue, rash, and nausea.

Recovery is generally indicated if, after the fever subsides, the patient is eating well and remains alert. Conversely, if the fever is gone but the patient still feels tired, has a poor appetite, experiences vomiting, abdominal pain, sluggishness, difficulty breathing, or cold hands and feet, immediate medical attention is necessary. Delaying a hospital visit by being complacent and returning to school or work while still weak can lead to severe consequences.

Close monitoring of the patient and strict adherence to a doctor's instructions are vital. Seek emergency medical care at a hospital immediately if any of the following symptoms appear: severe abdominal pain, persistent vomiting, extreme fatigue, bleeding gums, nosebleeds, vomiting blood, black stools, scanty urination, or difficulty breathing.

As the dangerous phase begins, dengue patients often experience reduced or absent fever, so vigilance is essential. *Photo: Vecteezy*

Dengue fever is caused by the Dengue virus, transmitted from person to person through the bite of an infected female Aedes aegypti mosquito. Climate change and urbanization are altering dengue epidemiology. The disease is no longer strictly seasonal, with sporadic cases occurring year-round. The outbreak cycle is also shortening, trending from approximately 5 years down to three to 4 years, and in some areas, as frequently as every two years.

The Dengue virus has four distinct serotypes, and individuals can contract the disease multiple times throughout their lives, with subsequent infections often carrying a higher risk of severity. Vietnam is currently experiencing its peak dengue season, resulting in a rise in cases and outbreaks across many provinces and cities. To prevent the disease, residents should eliminate mosquito larvae, remove mosquito breeding sites, avoid mosquito bites by wearing long clothing, sleeping under mosquito nets even during the day, and getting vaccinated as advised by a doctor.

The dengue vaccine provides over 80% protection against infection and reinfection by all four Dengue virus serotypes, and reduces the risk of hospitalization by over 90%. This vaccine is administered to children from 4 years old and adults, with a schedule of two doses given three months apart. Even those who have previously contracted dengue can be reinfected by a different virus serotype, underscoring the importance of not being complacent.

Doctor Nguyen Duc Ba Dat, Medical Manager, VNVC Vaccination System.

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