It’s not too late to be vaccinated against the flu.

And the recent deaths of 6 children in the states of New York, Boston, and Colorado points to the importance of getting vaccinated every year.

“The flu shot takes about three weeks to work and, with this being a late flu season, three weeks isn’t bad,” said Dr. Marc Siegel, a FOX News contributor and author of the book, “Bird Flu: Everything You Need to Know About the Next Pandemic.”

“It looks like the flu season will go until late March, early April this year,” he continued. “Anybody with asthma or a weakened immune system, as well as pregnant women and the very young and very old should be vaccinated.”

Hunter Pope, a seventh-grader at Boston Latin Academy who died over the weekend from the flu, was not vaccinated because he lost his permission slip, according to his mother.

Often used interchangeably to describe a cold or a stomach virus, influenza or the flu is a serious and potentially deadly illness that kills some 30,000 Americans, mostly the elderly, each year. More than 80 children died from the flu last year.

Siegel said children and teens are human “petri dishes” and the flu is a disease that “really spreads” in schools, which is why the Centers for Disease Control and Prevention are now recommending that all youths age 18 and younger get vaccinated.

“That could be the reason why we’re having a mild flu season because we’re vaccinating so much this year,” Siegel said, adding that the flu vaccination appears to be a good match for the flu strains circulating this season.

“H1N1 is the prevailing strain this year and, interestingly, it’s a distant descendent of the Spanish flu,” he said.

Although the vaccination seems to be a good match, Tamiflu – a prescription drug that if used within 48 hours of getting the flu lessens symptoms – does not appear to be a match for the circulating strains, Siegel said.

Siegel said children suspected of having the flu should be taken immediately to their physicians for nasal swabs to determine if it is indeed influenza.

“If it is the flu, you should keep the child away from other kids, keep them well-hydrated and monitor their mental status,” he said. “If they’re not responding to medicine and you can’t control the fever or the child seems lethargic, get them to a doctor right away.”