'Highest Level in 10 Years' Norovirus Outbreak Causes Frequent Reinfections... Emergency Alert Issued

More Than Half of Patients Are Infants and Young Children
Number of Rotavirus Cases Doubles Compared to Last Year

The number of patients infected with norovirus, one of the representative winter diseases, has reached the highest level in 10 years. Along with this, rotavirus infections have also surged, with the number of patients doubling compared to the same period last year.

Norovirus infection mainly occurs through the consumption of contaminated water (groundwater) or shellfish such as oysters, or through contact with infected individuals. Transmission via droplets is also possible. Photo by Getty Images

On the 10th, the Korea Disease Control and Prevention Agency announced the results of sample surveillance of gastrointestinal infections at 210 hospital-level medical institutions. The number of norovirus infection patients shown in these results has been continuously increasing since the first week of November last year. The specific patient numbers were ▲372 in the second week of January ▲390 in the third week of January ▲469 in the fourth week of January. This is the highest level in the past 10 years. The number of patients in the fifth week of January, which included the Lunar New Year holiday, was 347, but this appears to be a decrease due to the holiday period. Among the patients, the proportion of infants and young children aged 0-6 was more than half, at 51.4%. As of the fourth week of last month, among all patients, those under 1 year old accounted for 9.2%, and those aged 1-6 accounted for 42.2%.

Norovirus mainly spreads among infants and young children from late autumn to early spring (November to March). It is primarily transmitted through ingestion of water (groundwater) or shellfish such as oysters contaminated with norovirus, or through contact with infected patients, and droplet infection is also possible. Norovirus is highly contagious, and the immunity period after infection is short, so even if infected once, reinfection can occur, requiring caution.

When infected with norovirus, symptoms such as vomiting and diarrhea appear within 12 to 48 hours, sometimes accompanied by abdominal pain, chills, and fever. Most patients recover after 2 to 3 days. Since there is no vaccine, it is important to pay attention to hygiene for prevention. It is better to wash hands with soap for more than 30 seconds rather than using hand sanitizer, and when preparing food ingredients, wash them under running water and cook thoroughly at 85°C or higher for more than 1 minute before consumption.

Norovirus Structure Image

Along with norovirus, rotavirus is also spreading. As of the fourth week of January, the number of rotavirus patients was 123, an increase of 105% compared to the same period last year. Among all patients, those under 1 year old accounted for 9.8%, and those aged 1-6 accounted for 30.9%, making the proportion of infants and young children aged 0-6 40.7%.

Rotavirus has a similar infection route to norovirus, and symptoms such as vomiting, fever, and diarrhea appear within 24 to 72 hours after infection. Symptoms usually last for 4 to 6 days. Especially, rotavirus is easily transmitted through contaminated materials on diapers or toys via hands and mouth, so strict infection control is essential in newborn rooms, postpartum care centers, and daycare centers.

Proper handwashing is essential to prevent norovirus.

Rotavirus vaccination is available free of charge for infants through the national immunization program. The number of doses and schedule vary depending on the vaccine type. Medical institutions and public health centers where vaccination is available can be checked on the Vaccination Helper website.

Rotavirus patients should refrain from attending daycare, school, or work until 24 hours after symptoms disappear, and norovirus patients until 48 hours after symptoms disappear. It is also advisable to separate bathroom and living spaces from other family members. Additionally, to prevent virus spread through droplets after bowel movements, the toilet lid should be closed before flushing.