Holiday gatherings are expected to cause a spike in respiratory syncytial virus (RSV) infections across the country.

RSV is a highly contagious and potentially deadly virus that can cause respiratory disease. Symptoms include fever, worsening cough, and restricted airways leading to trouble breathing.

Most people recover in a week but as the last RSV season lasted longer and was more severe than usual, doctors are warning people to stay vigilant — especially those who care for infants and the immunocompromised.

Children under five years old are being hospitalized with respiratory illnesses at a higher rate than any other age group, and babies younger than six months old are at the highest risk, according to the Centers for Disease Control and Prevention.

Every year the virus causes about 58,000 to 80,000 hospitalizations and between 100 to 300 deaths in children younger than 5 years old, the CDC reported.

The health agency has already reported a sharp rise in cases in the last two weeks.

“RSV is a very common virus. Most children in the United States get infected by the time they’re 2 years of age,” Dr. Jeffrey Kahn, chief of infectious diseases at Children’s Health, Dallas, and professor of pediatrics at the University of Texas Southwestern Medical Center, told ABC News on Thursday.

To prevent children from getting sick, people who are around babies should consider wearing a mask during or after traveling.

They should also wash their hands for at least 20 seconds before holding a baby.

Studies have also shown that breastfed babies are less likely to have complications of RSV as experts believe components in breast milk help boost a baby’s immune system.

However, the best precaution to take is to get preventive shots.

“For the first time in decades, really, maybe since the virus was discovered, we have some very useful tools now to prevent RSV infection,” Kahn said.

There are two protective shots available for babies, which both contain antibodies and two RSV vaccines available for adults 60 and older.

Another vaccine recently received a formal endorsement from the CDC to be given during pregnancy to protect infants.

“If you’re an older person, or pregnant, you need to remember that vaccinating yourself could go a long way to protecting our youngest, most at risk,” Dr. Julia Arana, medical director of the hospitalists team and chief of staff at East Tennessee Children’s Hospital, told ABC News.