Now’s a good time to get your flu shot.

The number of deaths from the flu this season reached 1,800 nationwide, including 22 children, and the illness is spiking earlier than it has in years.

At least 300 people died from the flu in the week ended Dec. 21.

With flu widespread in the south and Puerto Rico, vacationers returning from holiday trips could bring an unwelcome souvenir back to the Big Apple.

None of the children who died were in New York City, according to data from the Centers for Disease Control. It is unclear if the city has determined a cause of death for a 2-year-old girl found dead in Park Slope on Dec. 14 who had earlier been treated for the flu.

Children 2 and younger are at high risk from flu, as are adults 65 and older and pregnant women.

The week before Christmas, flu cases were responsible for over 5% of all visits to Big Apple emergency departments, which is how the CDC tracks flu outbreaks. That’s higher than it’s been since at least 2016, and well above the expected rate just below 2%.

This time last winter, that figure was around 3%. It didn’t reach 5% until mid-January 2019, and it peaked in mid-February, with nearly 9% of all ER visits related to flu symptoms.

Outbreaks are heavy in 39 states, including New Jersey and Connecticut. The CDC estimates that so far this season there have been at least 3.7 million flu illnesses, and 32,000 people were hospitalized.

Flu vaccines are still available around the city.