After a one-year vacation, the flu season in the United States arrived as scheduled, and the number of flu hospitalizations increased, and two children were reported to have died.

Last year’s flu season was the lowest on record. This may be because COVID-19 measures—school closures, distances, wearing masks, and travel cancellations—prevented the spread of flu, or because the coronavirus somehow transferred other viruses Push aside.

“It makes myself more of a normal flu season,” said Lynnette Brammer, who tracks flu-like illnesses at the Centers for Disease Control and Prevention.

Brammer said, “Unfortunately, when flu activity intensifies, child deaths are what we expect. This is a sad reminder of how severe the flu can be.”

During last year’s unusually mild flu season, a child died. In contrast, 199 children died of influenza two years ago and 144 children the year before.

In the latest data, the U.S. capital, Washington, DC, has the most intense influenza activity, and the number of states with high influenza activity has increased from three to seven. Data released by the CDC on Monday showed that the states with high influenza incidence are New Mexico, Kansas, Indiana, New Jersey, Tennessee, Georgia and North Dakota.

Brammer said that the type of virus circulating this year tends to cause the most serious diseases, especially the elderly and young children.

Getting rid of the flu last year makes this year’s flu vaccine plan even more challenging. Brammer said that so far, the circulating viruses appear to be in a slightly different subgroup from the vaccine’s target, but it is “too early to know” whether this will weaken the vaccine’s effectiveness.

Brammer said: “We will have to see what the impact of these small changes” will be. “The flu vaccine is the best way to protect yourself from the flu.”

There are early signs that compared with last year, the number of people receiving flu vaccines has decreased. Brammer said that since hospitals are already overcrowded by COVID-19, getting the flu vaccine and taking other preventive measures are more important than ever.

“Cover your mouth when you cough. Wash your hands. If you are sick, stay at home,” Brammer said. “If you do have the flu, you can discuss antiviral drugs with your doctor, which can prevent serious illness and help you stay away from the hospital.”