Health surveillance systems and several hospitals across Vietnam have reported a rising number of adenovirus infections, with children accounting for the vast majority of cases.
Since the beginning of the year, the National Children's Hospital in Hanoi has recorded more than 2,700 confirmed adenovirus infections, three times as many as during the same period in 2025. In the first days of July alone, the hospital admitted a further 383 children, indicating a rapid increase in recent weeks.
The Ministry of Health said there is currently no evidence of unusual changes in the virus, the scale of transmission or the severity of illness within the community. Health authorities are continuing to closely monitor the situation while strengthening disease surveillance, early detection and rapid outbreak response.
Adenovirus can infect people of all ages throughout the year. It most commonly causes respiratory illnesses, with symptoms including fever, cough, sore throat and a runny nose. The virus can also lead to conjunctivitis, gastrointestinal disorders and other conditions.
Most patients experience mild illness and recover without complications. However, severe disease can occur in young children, older people, those with underlying medical conditions and individuals with weakened immune systems.
Conjunctivitis, commonly known as pink eye, can be caused by viruses, bacteria, allergies or environmental irritants. Adenovirus is among the most common viral causes.
The virus spreads through respiratory droplets, tears and direct contact with infected individuals, contaminated hands, shared objects and contaminated surfaces. It can also spread easily in crowded settings such as households, schools, playgrounds, childcare centres and swimming pools where hygiene, water treatment or surface cleaning standards are inadequate.
Health officials warned that the current summer holiday period, which includes increased travel and large gatherings, may heighten the risk of transmission. Children are spending more time in classrooms, recreational facilities and swimming pools, creating favourable conditions for the virus to spread.