In healthy children and adults, the virus typically causes mild, cold-like symptoms; but it can cause more serious disease in infants younger than 12 months old, or adults over age 65, according to the Centers for Disease Control and Prevention (CDC). In these more serious cases, the virus spreads from the upper respiratory tract to the lungs, potentially leading to pneumonia, inflammation of the lungs‘ air sacs (alveoli), or bronchiolitis, inflammation of the lungs’ small airway passages.
Infants are particularly at risk for severe disease because of their tiny airways — which, when inflamed, can easily compromise breathing — as well as their immature immune system, Ramilo said. “When you look at the number one cause of hospitalization in the first year of life, the number one is RSV,” Ramilo told Live Science. It’s a “very problematic pathogen,” Ramilo added, and the infection leads to millions of doctor visits and thousands of hospitalizations each year.
Symptoms of RSV often resemble those of the common cold. According to the CDC, typical symptoms include:
- Runny nose/congestion
- Decrease in appetite
- HeadacheIn infants, additional symptoms can include fussiness and poor feeding, according to the American Academy of Pediatrics (AAP).Symptoms typically appear within four to six days of exposure to the virus, according to the Mayo Clinic. In severe cases, the Mayo Clinic says symptoms can also include:
- Difficulty breathing or rapid breathing
- A bluish color of the skin caused by lack of oxygen
- Severe coughPeople should seek immediate medical care if they experience difficulty breathing, a high fever or a blueish color of the skin, according to the Mayo Clinic.
RSV can spread through the air when an infected person coughs or sneezes, or through contact with contaminated surfaces. The virus can survive for up to six hours on hard surfaces, such as toys and doorknobs, and can survive for about 30 minutes on unclean hands, according to AAP.
Children often spread the virus to others at school or in daycare settings, according to the CDC. Those who are infected with the virus are typically contagious for three to eight days; but people with weakened immune systems may be contagious for much longer, up to four weeks and even after symptoms clear up.
In the U.S., RSV typically circulates from late fall to early spring, but the timing in a given region can vary from year to year, according to the CDC.
In 2020 and 2021, the U.S. saw an unusual trend in RVS infections. According to a report published in July 2021 in the CDC journal Morbidity and Mortality Weekly Report, RSV activity in the U.S. dropped to historically low levels from about April 2020 to April 2021. But when COVID-19 restrictions began to lift in the spring of 2021, RSV surged, leading to an unusual summer spike in RSV infections, the report said.
The reason behind these trends still isn’t clear, Ramilo said. Although some experts suspect that measures to reduce the spread of COVID-19 taken in 2020, such as mask-wearing and social distancing, also reduced the spread of RSV, Ramilo said he doesn’t think this is the whole story. “I don’t think we can explain everything from nonpharmaceutical interventions” like masking wearing and social distancing, said Ramilo, who noted that other respiratory viruses, such as rhinovirus and adenovirus, still circulated in 2020, despite restrictions.
What is clear is that the summer of 2021 saw a dramatic increase in RSV hospitalizations. “Here, we saw a big increase in July and August,” at the same level that’s usually seen in December or January, Ramilo said. In 25 years of studying RSV, “this is the first time we’ve seen an outbreak in the middle of July and August,” he said.
RSV is different from COVID-19. RSV belongs to a family of viruses known as pneumoviruses; whereas SARS-CoV-2, the virus that causes COVID-19, belongs to a group of viruses known as coronaviruses. Since RSV and SARS-CoV-2 are both respiratory viruses, their symptoms can be similar, according to the Mayo Clinic.
It is possible to be infected with both RSV and COVID-19, but such coinfections do not appear to be common, Ramilo said. Doctors have been on the lookout for these coinfections because it’s known that children can sometimes be infected with RSV and other coronaviruses that cause the common cold, Ramilo said. But “we haven’t seen very many cases [of RSV and COVID-19 coinfections], just a handful,” he said.
According to the CDC and AAP, people at risk for severe RSV infections include:
- Premature babies, particularly those born before 29 weeks
- Children younger than 2 years old with congenital heart disease or chronic lung disease
- Children or adults with weakened immune systems due to a medical condition (such as cancer) or medical treatment (such as an organ transplant)
- Older adults, especially those with chronic heart or lung disease
Each year, RSV is responsible for about 2.1 million visits to the doctor and 58,000 hospitalizations among children younger than 5, according to the CDC. In adults over age 65, the virus causes about 177,000 hospitalizations and 14,000 deaths each year.
There’s no specific treatment for RSV. Because RSV is caused by a virus, not a bacterium, antibiotics won’t work to treat the infection. Most people who catch RSV get better within a week or two without medical intervention.
Over-the-counter medicines, such as acetaminophen or ibuprofen, can help manage symptoms, such as pain and fever. Children should never take aspirin, according to the CDC. People can also use nasal saline drops and suctioning to help with a stuffy nose, according to the Mayo Clinic. Those with an infection should drink plenty of fluids to stay hydrated.
RSV may also increase the risk of ear infections in children, according to the AAP. If a child develops a bacterial ear infection, their doctor may prescribe antibiotics.
In rare cases, people with RSV are hospitalized, and their treatment in the hospital may include fluids, additional oxygen or use of a mechanical ventilator to help with breathing.
In the U.S., about 3% of infants with RSV infection need to be hospitalized, Ramilo said. But most are able to go home within two to three days, according to the AAP.