Flu Cases Surging Again: Infection Can Also Be Prevented by Humidifying Indoor Spaces

Editorial

16:39 JST, February 12, 2026

The number of flu patients has spiked again, reaching an alert level for the second time since November.

The cold weather, combined with low rainfall causing dry air in many areas, seems to have contributed to the resurgence. People should check that they are taking measures to prevent infection.

During the week of Jan. 26-Feb. 1, more than 114,000 flu patients were reported across about 3,000 medical institutions nationwide, according to the Health, Labor and Welfare Ministry. That is nearly double the previous week’s figure.

The number of patients per medical institution exceeded an alert level of 30. By prefecture, Oita had the highest number of patients per facility at 52, followed by Kagoshima, Miyagi, Yamanashi and Chiba.

The number of elementary and junior high schools that either closed or suspended classes nationwide more than doubled from the previous week, reaching 6,415 schools.

Basic measures, such as handwashing and wearing masks in crowded places, are essential.

This season’s flu began spreading in September, with the number of patients exceeding an alert level in November. The number declined after that but began rising again in January.

In the past 10 years, the number of patients has never, in one flu season, returned to an alert level after declining from such heights. People may have let their guard down after the spike began to fade.

While the initial outbreak was dominated by the influenza A virus, the B virus began spreading around the end of last year and may be the cause of the second peak. Those who have already had the A virus can still contract the B virus, so caution is required.

It seems that the B virus does not always cause the high fever seen with the A virus. Asymptomatic spread must be avoided. It is important to avoid overexertion, rest and see a doctor promptly if you feel unwell.

This winter has seen record-low rainfall, particularly along the Pacific coast, leading to drier air than usual.

Viruses are more active when the humidity drops below 40%, so indoor spaces should be humidified. A dry nose and throat weakens the body’s ability to expel viruses, making it susceptible to infection. Wearing a mask can help keep the mucous membranes moist.

The vaccines currently available are also effective at blocking the B virus. A shot is said to be effective for about five months. Those who have not been vaccinated yet should consider getting inoculated, especially to prevent severe illness.

The health ministry said there have been no reports of drug shortages this time, but it should monitor the supply closely.

(From The Yomiuri Shimbun, Feb. 12, 2026)