One night your playful kid won’t go to bed; the next day the same youngster refuses to get up, complains of a headache, body pains and a fever. What happened?

Well, your child may have contracted the flu.

This season’s outbreak is the worst in years. What warning signs should parents look for to know when it’s time to call the doctor, or to decide whether the ailment is a cold and not the more debilitating influenza?

“The symptoms for cold and flu can look the same initially — the runny nose, cough, sore throat and fever — but with the flu it’s just an abrupt onset of higher fever (above 101 degrees) – just out of nowhere,” said Dr. Linda Howelton of Northeast Pediatric Associates in Schertz.

Then you get body aches, and for children, vomiting and diarrhea.   

Symptoms can continue for a week or more; fevers three to seven days. For some children, the cough can persist a couple of weeks, according to Courtney Smith, a pediatrician with The Children’s Hospital of San Antonio Primary Care – Dominion Crossing.

The best protection against influenza is a flu shot, even though this year’s vaccine isn’t as effective as scientists hoped. However, medical officials agree it can still mitigate sickness, even in kids.

Michael Magoon, a physician at The Emergency Clinic of Alamo Heights, said reports indicate this year’s inoculation is 36 percent effective.

“It’s probably a little better than that, but it depends on the study quite frankly,” he added.

A lot comes down to the particular strain of flu that’s circulating. Influenza is classified into two main types, A and B, and then there are a couple of different strains for each.

“So the one that’s wreaking havoc this year is the Flu A H3N2 strain. This is the one that’s been hitting most children who have gotten the vaccine,” Smith said.

The number of humans afflicted each year is based on the strain’s aggressiveness and a combination of the flu vaccine’s efficacy and how much the virus spreads. Annually, scientists play a guessing game predicting which strains will dominate.

Should your child receive home treatment or see a doctor?

“Watch them for 24 hours, for a child who’s over 2. If they have high temperature, vomiting and are tired, then you want to go ahead and get them seen because if doctors are going to give them Tamiflu, which is the antiviral medicine for both strains, it needs to be done within 48 hours of the onset of the illness,” Howelton said.

The very young and very elderly, or those with weakened immune systems, should take preventive action. Those under 24 months are also more at risk. Meanwhile, children who have asthma, cystic fibrosis, diabetes or other maladies need attention as soon as possible since the flu can hit them harder.

Smith suggested parental resources should include the American Academy of Pediatrics’ website, healthychildren.org.

The Centers for Disease Control and Prevention also has some timely information, Smith said. The website is www.cdc.gov.

How can children avoid getting the flu?

In short, wash hands quite often and cover noses or mouths when sneezing or coughing, as respiratory droplets transmit the flu.

“Some people aren’t aware that you can get influenza A in December and get influenza B in January,” Howelton said.

Other bugs parents should monitor include RSV – human respiratory syncytial virus. This contagion makes kids feel asthmatic.

Plus, the rotavirus is still around and can produce severe diarrhea and dehydration in infants and toddlers. Inoculations are administered to 2-, 4- and 6-year-olds, so it’s less prevalent than in past years.

Staff writer Collette Orquiz contributed to this report.