Robyn Correll’s son caught the flu before age 3, which put him at high risk. Dozens of children have died in this season’s flu outbreak. (Courtesy Robyn Correl/Courtesy Robyn Correl)

I knew my son was sick when he didn’t want the iPad. Normally, my energetic toddler would have been begging to get his sticky fingers on the screen, but when I set it down next to him, he didn’t even reach for it.

Later that night, I asked the ­urgent-care doctor if it could be the flu. She looked over at my boy’s rag-doll body sprawled across the table in the exam room, his eyes glassy, staring blankly at the wall. “I don’t think so,” she told me. “He doesn’t have a fever.” Or a cough or a runny nose — some of the classic signs of flu.

A rapid influenza diagnostic test in his pediatrician’s office the next morning said otherwise. It came back positive for influenza Type A, and we started him on antiviral medications that afternoon. The next few days, I watched as he struggled to fight off a virus that has already killed at least 84 children this season. He eventually recovered, but it was the sickest I had ever seen him and the most worried I’d ever been.

I had good reason to be concerned. At 2½ years old, he was particularly at risk for severe illness, according to Mary Healy, an associate professor of pediatrics at Texas Children’s Hospital and Baylor College of Medicine in Houston. Children younger than 5 are statistically more likely to have dangerous complications if they get the flu.

He also had many of the warning signs parents should watch for, such as a severe headache, persistent vomiting and not waking up or interacting. Most concerning to his doctor was that he wasn’t holding down fluids or going to the bathroom — a sign of dehydration, which can make it harder for the body to defend itself against an infection. Some other important things to watch for, according to Healy: being too breathless to finish a sentence, turning blue, being more irritable than normal or appearing to get better and then taking a sudden turn for the worse. Any of the above should send parents running to call their child’s doctor.

This is especially true for children with underlying medical issues such as asthma, heart or neurological conditions, or diabetes — all of which can make it harder for young children to fight off the flu, Healy said. While most children with the flu are able to recover just fine, some don’t.

Five-year-old Joseph Marotta had been a healthy kindergartner before he died of swine flu in 2009. During his 10-day stay in the hospital, doctors diagnosed him with pneumonia and, later, the H1N1 influenza virus, but they never seemed overly concerned, said Joseph’s mother, Serese Marotta. She was talking with her son about Halloween costumes when he lost consciousness. A little while later, he was gone.

“It’s the most horrible thing that you can ever witness,” said Marotta. Afterward, his doctors told her that he was the 85th child to die of the flu that season. She was floored. “Honestly, I didn’t realize that healthy children and adults could die of flu,” she said.

The experience led her to seek out other families who had lost children, and she eventually ended up volunteering with Families Fighting Flu, a nonprofit organization dedicated to educating parents about the importance of flu prevention. Now, nearly a decade after losing her son, she is the organization’s chief operating officer and shares Joseph’s story with people throughout the country. Like many of the parents involved with the organization, she hopes her son’s experience will help alert people to how dangerous the flu can be.

An estimated 1,300 or more children died of the flu from 2007 to 2017, according to the Centers for Disease Control and Prevention. Nearly a quarter of those deaths happened during the 2009-2010 flu season. Tens of thousands of adults have died of flu-related causes in the past decade. While it’s difficult to pin down exactly how many, the CDC estimates that the virus is responsible for 12,000 to 56,000 deaths a year.

In some cases, Healy said, death occurs when the flu makes existing medical issues, such as heart and breathing problems, worse. In others, the flu virus can attack the body’s organs, causing fatal sepsis or inflammation. The respiratory and immune systems of very young children — especially those in their first year of life — aren’t fully developed, and that can cause the effects of the virus to be more deadly.

One crucial way you can help prevent these things is by getting a flu shot. While a lot of attention is paid to how effective the flu vaccine is or isn’t, many doctors — including Healy — will tell you that that’s only a part of why the vaccine is recommended for everyone older than 6 months.

“Flu vaccines are not perfect,” Healy said. But she’s quick to add, “Even if it isn’t a perfect match, some protection is better than none.”

That’s because getting vaccinated can help your body build up some immunity against the flu in advance, so that it has a head start in fighting off the disease quickly. Sometimes that’s enough to keep you from getting sick, but even if it’s not, that protection can help make any symptoms you do get milder and go away faster. Even in years when the flu vaccine isn’t a perfect match for circulating strains, it can still prevent tens of thousands of hospitalizations and even deaths.

When I shared my son’s experience with Marotta, she told me there were a lot of similarities with Joseph’s story, at least in the beginning: vomiting, not acting like himself, urgent-care visits and lethargy. There was, however, a notable difference: My son got the flu shot in the fall, but Joseph never got the chance. No vaccine against H1N1 was available in his area before he got sick.

Is it likely the flu vaccine saved my son’s life? Could it have saved Joseph’s? It’s impossible to know, but research does offer some clues. In recent flu seasons, 4 in 5 children who died of the flu hadn’t been vaccinated — and that’s almost certainly not a coincidence. Research shows vaccination helps reduce the risk of healthy children dying from the flu by two-thirds. While the best time to get the vaccine is in September or October before flu season begins in earnest, public health and medical experts continue to stress it’s not too late to get a flu shot.

For her part, Marotta always vaccinated herself and her children, but now flu shots have a particular significance.

“It’s almost like a ceremony for me now,” Marotta said. “I take that moment, and I take a breath and go, ‘This is in honor of Joseph.’ ”