Originally Published: 27 OCT 22 09:08 ET

By Katia Hetter, CNN

(CNN) -- A common respiratory virus, respiratory syncytial virus, is surging in the United States, leading to some children's hospitals being overwhelmed. The influenza virus is also on the rise, along with other viruses — such as adenovirus and rhinovirus — that cause the common cold.

At the same time, children are back at school and families are returning to many in-person activities, often without the mitigation measures applied during Covid-19, heightening the possibility for viral spread.

What kinds of respiratory infections can be treated at home — and with what treatments? Which symptoms should prompt a call to the doctor, or for parents and caregivers to bring their children to the hospital? When should children stay out of school? And what are the precautions families can take to reduce the spread of respiratory viruses?

To help us with these questions and more, I spoke with CNN Medical Analyst Dr. Leana Wen, an emergency physician, public health expert and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She is also author of "Lifelines: A Doctor's Journey in the Fight for Public Health" and the mother of two young children.

CNN: Why are respiratory infections on the rise?

Dr. Leana Wen: They have always been common among children. Before Covid-19, it was the norm, especially during the fall and winter, for schoolkids to have runny noses and coughs.

Now, they may be increasing in part because mitigation measures taken during the pandemic — like social distancing, masking and avoiding large gatherings — resulted in fewer respiratory viruses being spread over the past two winters. As a result, a lot of kids don't have the immunity they normally would.

My own kids have already had at least three bouts of respiratory illness each since they started back at kindergarten and preschool less than two months ago. Thankfully, they recovered well and did not get severely ill, but I certainly understand the worry and distress that parents and caregivers feel when our children are sick.

CNN: Which respiratory infections can be dealt with at home?

Wen: The vast majority of respiratory infections in children can be managed at home with fluids, fever-reducing medicines and rest. What's causing the infection is generally not the key determining factor in whether a child needs hospital care — it's how the child is doing.

Respiratory syncytial virus, also known as RSV, is concerning on a public health level because some hospitals are getting full with children who have it. Prior to the Covid-19 pandemic, the US Centers for Disease Control and Prevention estimated that virtually all children will get RSV before their second birthday — and that some 58,000 kids will end up being hospitalized for it every year. Clearly, RSV is a very serious infection among some children, and parents should know what to watch for to spot severe illness. But also keep in mind that the vast majority will have mild, cold-like symptoms and will not need to be hospitalized.

The same goes for other viruses. Influenza can cause very severe illness, as can Covid-19. However, most cases in children do not result in hospitalization, and symptoms can be managed at home. On the other hand, there are viruses that one typically associates with a mild cold, like adenovirus, that can cause some children to become very sick.

If you end up going to the emergency department, your child will probably get tested for Covid-19, influenza and RSV. Some pediatricians would do this too. If your child were hospitalized, they might get additional virus testing. But a lot of doctor's offices wouldn't provide such care because, again, the actual virus leading to the illness is less important in determining whether your child needs to be hospitalized than how your child is doing.

The exception is very young infants — generally those under 2 months of age — who are typically tested and monitored more.

CNN: What other risk factors should lead to parents watching for severe illness?

Wen: Newborns are very vulnerable. They have little immunity and not much physiological reserve, meaning that once they get sick they could become very ill very quickly. Premature babies are also at risk. Many of them have underdeveloped lungs. A baby born two months premature has a physiological age two months younger than a baby born at term on the same day.

There are other factors to consider, too, including for young kids who have significant heart and lung disease, or are severely immunocompromised. In all these situations, families should have a low threshold for calling their physician.

CNN: If a child is generally healthy and develops a fever, cough or runny nose, should parents and caregivers call the doctor? When should they rush to the hospital?

Wen: There are two major symptoms that should prompt concern in respiratory infections. The first is breathing difficulties. Look for struggled and fast breathing. For example, if your children are wheezing or grunting; if their nostrils are flaring; if they are belly breathing, meaning that the chest caves in during breathing and the belly goes out; or if their breathing rate is higher than normal.

The second is difficulty keeping hydrated. This is particularly a problem in babies. If they get stuffed noses, it can be hard for them to drink breastmilk and formula, and they could get dehydrated very quickly. If your child looks sleepy and isn't drinking, or if your baby is having a decrease in the number of wet diapers, call your doctor sooner rather than later.

Ongoing issues — for example, a mild fever that's been going for a few days — could probably wait for your pediatrician's office hours.

I'd advise that you have a plan before your child gets sick. A lot of pediatricians have an on-call service where you can reach your doctor or another health care provider within an hour, even at night and on weekends. Know if this possibility exists and have that number easily available to call. If your pediatrician is not reachable after hours, you should know which hospital you'd bring your child to if they were to become seriously ill. Ideally, it's a hospital close to you and that's staffed with pediatric emergency medicine specialists.

If you can't easily reach your doctor by phone in emergencies, have a low threshold to bring your child to the hospital, especially if you have a newborn or young baby. Breathing difficulties and inability to keep hydrated are good reasons to immediately go to the hospital.

CNN: When should kids stay out of school?

Wen: That depends on the policies at your child's school. Many schools ask that kids stay at home while they have fevers. They also shouldn't be in attendance if they are throwing up. Some schools may also require Covid-19 testing to make sure that what's causing the symptoms is not the coronavirus.

That said, it's probably not reasonable to ask that kids stay home if they have any hint of the sniffles. That could mean kids miss many weeks of school during winter months. Parents and caregivers should assume there are kids who are infected with some respiratory pathogens in their child's class at all times and take precautions accordingly. Some families may choose to mask. Others may go back to what they did pre-Covid, which is to stick with good hand hygiene and not being around vulnerable people when sick.

CNN: What types of precautions should parents and caregivers take?

Wen: Handwashing is a big one. Many of these respiratory pathogens travel through droplets: When someone sneezes or coughs, those droplets land on surfaces that someone else touches and then touch their nose or mouth. Encourage your kids to wash their hands frequently, and if they need to cough or sneeze, they should do so into their elbow or a tissue to reduce the spread of the droplets.

If a person in your household has a respiratory infection, it can be easily spread to other household members. You can reduce that risk by not sharing utensils or drinks with the person who is ill, and keeping the person who is sick away from vulnerable household members like newborns and the elderly. In general, families should also limit exposure for newborns and premature babies as much as possible.

There is no approved vaccine for RSV, but there is for the flu. Parents should get their kids the flu shot. They should get their kids vaccinated against Covid-19 if they haven't already, and assess their own family circumstances to determine whether they should get their children aged 5 or older the new bivalent booster.