Just in time for holiday traveling, your kids may have already delivered coal: the makings for strep throats, colds and the flu. What's worse: Exhaustion after tests and papers makes it tough for students' immune systems to shift into time-off mode.

Industrious kids can succumb to a sickness they've fought off at school. What helps the immune system, health professionals say, is to try to ease into the transition of traveling, and to exercise and drink plenty of fluids (but no sharing beverages).

Another tip for kids and adults: Cough or sneeze into your sleeve. That way, some of the bundle of bugs at school, at home, work or play will stay at bay.

Charlotte Cowan, M.D., a pediatrician, says that to help reduce the spread of respiratory illnesses such as colds and the flu, cover the mouth with the elbow instead of the hand. Also, she says, teach your child to use tissues for his runny nose, not his sleeve, mitten or bare hand, and then to throw the tissues away and wash his hands. Cowan is the author of a "Dr. Hippo" series of health books for kids, at www.drhippo.com.

Ways to boost your child's immune system, in addition to serving lots of fruits and veggies, include giving vitamin C and the mineral zinc, according to William Sears, M.D., a pediatrician who has practiced for more than 30 years. His Web site is www.askdrsears.com.

Pay close attention to symptoms and use informed judgment before going to your health care provider.

Here are tips from Sears on sorting out and treating common flu and sore throats:

About the flu: Your child doesn't seem himself, slows down, and has had a runny nose and some coughing. He complains of a headache and sore throat. Next, his body aches all over. He has a high fever and chills. His cough gets worse and he starts vomiting.

The flu virus, not treatable with antibiotics, is typically some combination of the above symptoms. Guidelines, Sears says:

--Focus on treating the symptoms that seem to bother your child the most by using ibuprofen for head and body aches and fever, and a nasal decongestant if needed.

--Keep your child hydrated with lots of fluids, given in small amounts at a time if necessary.

--Ibuprofen is often better for the aches and pains of the flu than acetaminophen.

About sore throats: Some sore throats are caused by a bacteria, strep, which can be treated with antibiotics. Other sore throats are caused by viruses and cannot be treated with antibiotics.

When your child starts complaining about his throat, Sears says, don't run your child to the doctor at the first sign. See which direction the illness is going. If your child begins to fit the picture of strep throat, go see your doctor.

Fever is common to strep throat. A child typically has swollen neck glands and pain with swallowing. Strep throat usually does not cause multiple symptoms such as runny nose, cough and congestion, Sears says. The illness can come with a red throat with bright red spots on the back of the palate and white pus on the tonsils, but not always.

It is uncommon for a child under age 3 to get strep throat, he says, and in older kids it is often difficult to tell whether your child has strep or has a severe sore throat. If your child is acting lethargic and looks very sick even when the fever is down, take your child to the doctor that day.

Pain relievers such as ibuprofen, aside from treating the fever, also will help with the headache, sore throat and body aches from the virus.

About fevers: What constitutes a normal temperature depends on the child, varies throughout the day and can range from 97 to 100.5 degrees, according to "The Children's Hospital Guide to Your Child's Health and Development" (Perseus, 2001). Talk to your pediatrician at a well-check about what a high fever range would be for your child, such as 102 to 103 degrees.

Parenting tip: Toothbrushes are known germ packers. Over the holiday break, get a new one for each family member. Be sure to switch toothbrushes after an illness.