Typically, RSV (Respiratory Syncytial Virus) starts to spread in the continental U.S. around the start of October—usually before the flu. But in 2022, RSV (as well as the flu) surged early, starting in the summer. It took everybody off guard and completely overwhelmed hospital systems, especially pediatric hospital systems.
The general consensus is that because of COVID-related precautions, the number of children who had never been exposed to RSV before was unusually high. Typically, babies first catch the virus during their first year of life. But when kids started to return to school and normal activities, it was not just infants experiencing their first exposure to RSV—it was also older kids. That provided an opportunity for the virus to spread early. Still, RSV is bad pretty much every year. Last year, however, was especially bad, given all the kids encountering it for the first time at the same time that COVID-19 and the flu were circulating.
WHAT WILL RSV SEASON BE LIKE THIS YEAR?
This year, we haven’t seen the same early surge of RSV. Because of that, researchers anticipate that the start of RSV season is likely to be at the more typical time—generally early October. Yet even on a normal time frame, this season could still be bad: Experts often see respiratory virus season in the Southern Hemisphere as a sort of preview of the respiratory virus season in the U.S. and Europe. And during their respiratory virus season this year, some parts of Australia saw 10 times as many RSV cases as they saw the previous year.
WHAT ARE THE SYMPTOMS OF RSV?
In older kids and adults, RSV—like many other respiratory viruses—causes cold-like symptoms, including runny nose, coughing, decreased appetite, fever, sneezing, and wheezing. Unlike the flu, where symptoms often appear all at once, the symptoms of RSV tend to appear in stages about four to six days after infection.
It’s difficult for parents to tell the difference among various respiratory viruses, but pediatricians can often quickly identify an RSV cough. Providers can also diagnose the virus with a test if needed, though there is no specific treatment for RSV—in most cases, kids just need rest, hydration, and sometimes ibuprofen or acetaminophen.
Most RSV infections go away within a week or two.
RSV IS SOMETIMES SEVERE IN YOUNG KIDS
RSV can cause inflammation of the small airways in the lung, known as bronchiolitis, and pneumonia, a lung infection. These can cause difficulty breathing, especially in young children, who have particularly small airways. People who are struggling to breathe often require hospitalization, where babies or young kids with RSV may receive oxygen, IV fluids, or—in the most serious cases—
HOW IS THE PROBLEM DEALT WITH IN KIDS?
In July, the FDA approved nirsevimab, a type of treatment known as a monoclonal antibody, to help prevent RSV in infants and younger children at higher risk for severe cases of RSV.
This product is not a traditional vaccine but it is intended to provide protection against infection that should last for at least five months.
Vaccines provide active immunization—they teach your body to recognize an infection with a specific virus and then to respond by creating antibodies that fight the infection. This shot just puts the antibodies directly into a child, in a process known as passive immunization. A traditional vaccine teaches the body to make antibodies, the means to cause the body to launch its own defense.
DOES THE ANTIBODY CAUSE SIDE EFFECTS?
When your body responds to an infection or to vaccination, the immune system’s response can cause side effects of varying severity, something that’s known as reactogenicity—that’s why your arm sometimes feels sore after a flu shot. But since this direct antibody injection skips the need for your body to react and create antibodies, this injection doesn’t appear to cause many side effects at all. In clinical trials, the most commonly reported adverse side effect was a mild to moderate rash at the injection site—though even that is uncommon.
There doesn’t appear to be any concern that the injection could cause a fever, which is what makes it safe to give to very young infants.
HOW EFFECTIVE IS NIRSEVIMAB?
According to clinical trial data from AstraZeneca and Sanofi, makers of Beyfortus (the brand name for nirsevimab), the injection is about 77 percent effective against hospitalization for RSV-associated lower respiratory tract infection, and about 76 percent effective against RSV infections requiring medical care.
WHO SHOULD GET NIRSEVIMAB, THE NEW ANTIBODY FOR KIDS?
According to recommendations from the CDC’s Advisory Committee on Immunization Practices, healthy infants who are under 8 months of age going into or during their first RSV season can get one dose of nirsevimab. Once a child reaches 8 months of age, they are no longer eligible, according to the American Academy of Pediatrics. Kids born during RSV season (Oct. 1 through March 31 in the continental U.S.) will ideally receive a dose during their first week of life, often at the hospital soon after they are born.
Some kids ages 8 months to 19 months who are at a higher risk for severe RSV are also eligible for a dose of nirsevimab during or shortly before the season. These include children with chronic lung disease or prematurity, severely immunocompromised children, children with cystic fibrosis with manifestations of severe lung disease, and American Indian or Alaska Native children, according to the AAP and CDC.
If nirsevimab isn’t available for kids at higher risk for severe RSV, there is another already available preventative antibody treatment, palivizumab, available for infants who were born prematurely and certain other higher-risk groups. But palivizumab provides protection for only about a month. To protect kids through the peak of the season, doctors typically recommend a five-dose course, with doses spaced about a month apart.
WHAT ABOUT THE RSV VACCINE FOR OLDER ADULTS?
RSV can cause serious complications for older adults, just like in young children. According to the CDC, between 60,000 and 160,000 older adults are hospitalized for RSV each year, with between 6,000 and 10,000 deaths. The highest-risk older adults include those with weakened immune systems, those with chronic heart or lung disease, and those living in nursing homes or other long-term-care facilities.
In May, the FDA approved Arexvy, a vaccine against RSV created by GlaxoSmithKline, for adults 60 and older, based on data showing it reduced the risk of developing lower respiratory tract disease by 83 percent. Commonly reported side effects include injection site pain, fatigue, muscle pain, headache, and joint stiffness.
That same month, the FDA also approved another similar vaccine called Abrysvo made by Pfizer, based on data showing it reduced the risk of lower respiratory tract disease by 89 percent. The most commonly reported side effects included fatigue, headache, pain at the injection site, and muscle pain.
There were also some rare events in the studies of both vaccines.
During clinical trials of Arexvy, three of the 17,922 participants experienced inflammatory neurological events within 42 days of vaccination. One participant developed Guillain-Barré syndrome (GBS). Two participants from another study of people who got both Arexvy and a flu vaccine at the same time developed a rare type of brain and spinal cord inflammation; one of them died. There were also several more cases of irregular heart rhythm, known as atrial fibrillation, in study participants who received the vaccine than there were in the placebo group.
During clinical trials of Abrysvo, three of 20,255 participants experienced inflammatory neurological events within 42 days of vaccination, including a case of GBS and a GBS variant, and another neurological event that involved a worsening of preexisting symptoms. There were also several more cases of atrial fibrillation in vaccine recipients than in placebo recipients.
Researchers and manufacturers will continue to monitor and investigate the potential risks of both vaccines.
Arexvy and Abrysvo are available for adults 60 and older now at pharmacies and healthcare providers. They should provide at least some protection for two seasons, according to the CDC, and can be administered alongside other vaccines like the flu shot.
WHAT ELSE TO KNOW ABOUT RESPIRATORY VIRUSES THIS SEASON
It’s not just RSV but also other viruses, i.e., flu, and COVID-19, that we need to prepare for right now. If there’s a vaccine for any of these illnesses you qualify for, you should get it. The best way to protect yourself from complications and dying is to get vaccinated. That is our best tool for protection.
Pediatricians tell people to try to get their flu shot before Halloween—“flu before boo,”—so to speak. COVID-19 boosters are likely to be available in the coming weeks as well, at least for some people who are at higher risk. Aside from that, typical precautions remain the best advice we have. Wash your hands regularly, try to stay home when sick, consider wearing a mask in crowded places, and don’t send sick kids to school.