Why RSV Surges May Soon Be a Thing of the Past

There’s a respiratory virus that’s crowding U.S. children’s hospitals, and it’s not influenza and it’s not COVID-19. This year, healthcare systems are seeing surges of an illness called respiratory syncytial virus (RSV).

As of the last week of October, babies under a year old were being hospitalized at a rate nearly nine times as high at the same point in 2019. The rate of hospitalization is now nearly nine times higher for people of all ages.

In most adults, RSV is no more severe than the common cold, and causes similar symptoms. But for young babies and older adults, the infection can cause severe lung inflammation and even lead to death.

There’s currently no antiviral treatment for RSV, and only one monoclonal antibody option to help prevent it. While many babies will recover from the illness after hospitalization, older adults are less likely to fare so well. For Americans older than 65, RSV causes as many as 10,000 deaths each year, not far off from the 16,000 deaths caused by flu in 2019.

One piece of good news: Thanks to an influx of developments in vaccines and treatments, this could be the last year RSV wreaks such havoc.

Some of the largest pharmaceutical companies have shared data from Phase 3 clinical trials on their RSV vaccines this year. Some vaccines are intended to protect older adults. Others will inoculate newborns via pregnant mothers who get the shot.

Trial data so far indicates these vaccines will be 70% or more effective at preventing severe disease in the youngest kids, and 80% or better at protecting older adults.

“RSV appears to be one of the last highly contagious serious diseases of childhood,” William Schaffner, MD, medical director of the National Foundation for Infectious Diseases (NFID) and professor of medicine in the division of infectious diseases at the Vanderbilt University School of Medicine, told Verywell. “The development of vaccines is a very, very exciting prospect.”

Lifted COVID Restrictions Contribute to Surging Cases

As COVID-19 prevention restrictions have dropped, respiratory viruses like RSV have come roaring back.

“We’re back in school, we’re taking off our masks, we’re going to daycare, we’re going to birthday parties—children are interacting. This has given these respiratory viruses an opportunity to spread earlier than they usually do,” Schaffner said.

This mix of disrupted seasonal patterns for respiratory diseases and having a population of children who are naïve to the infection makes for a “perfect storm,” Vandana Madhavan, MD, MPH, clinical director of pediatric infectious disease at Mass General for Children, told Verywell.

Now, pediatric hospitals are seeing an influx of cases.  

“In one of our community hospitals, not only is the floor overflowing with patients waiting in the emergency department longer, but the vast majority of patients that are being admitted have RSV,” Madhavan said.

How Common Is RSV Normally?

In a typical year, 1% to 2% of children sick with RSV—roughly 58,000 kids—end up being hospitalized, and 100 to 500 U.S. children younger than 5 die of the disease. While most children will recover after receiving oxygen and hydration support in the hospital, this medical care can be costly for families, Madhavan said.

Other than supportive care like oxygen and fluids, there’s currently no treatment for RSV. However, for those at a low risk for complications, contracting RSV can protect them in the long run.

Most people have a few RSV exposures in their lifetime. While immunity to the virus doesn’t last very long after infection, it will prevent future infections from being so severe.

Is RSV Preventable?

In the absence of an authorized vaccine, there’s only one preventive option for those at high risk of severe illness. The monoclonal antibody, called palivizumab (Synagis), was developed 25 years ago to prevent severe disease in high-risk infants. But unlike a vaccine, the treatment must be given every month during RSV season to reduce the risk of severe infection.

While researchers have been trying to develop an RSV vaccine for years to help prevent the virus, the Food and Drug Administration (FDA) still hasn’t authorized one for use. The first experimental RSV vaccine was developed in the 1960s. But among children who received it, those who were vaccinated got sicker and were more likely to die of the infection than the babies in the placebo group.

Then, in 2013, a structural biologist named Jason McLellan made a discovery that allowed scientists to create a vaccine to target RSV before it infected cells. His work also contributed to the development of the COVID-19 vaccines.

Vaccine manufacturers are now reaping the benefits of this advancement. Several companies have started vaccine trials using this protein. Results from the first successful Phase 3 trials have started to roll in this year.

Vaccines Are on the Horizon

Protecting vulnerable children has long been a goal for scientists. But as with the COVID-19 vaccines, pharmaceutical companies are first vaccinating adults before testing their products in the youngest children.

The vaccine candidates closet to development are not intended to inoculate children directly, but rather pregnant mothers. The antibodies from these maternal vaccines can travel through the placenta to the fetus so that the child is protected at birth.

Last week, Pfizer announced that its maternal RSV vaccine was 82% effective at preventing severe RSV in babies through 3 months old, and 70% effective through 6 months. As with most vaccines, a maternal RSV shot isn’t likely to prevent disease entirely, but may fend off the most severe outcomes.

“There are going to be younger babies who have RSV who might still just have upper respiratory symptoms, or even still have bronchitis…but are not working hard to breathe, are not dropping their oxygen level, are not getting dehydrated, aren’t needing to be hospitalized,” Madhavan said. “We’re really focused on minimizing the most severe complications with a vaccine.”

At the same time, about 177,000 older adults are hospitalized with RSV, and roughly 14,000 die of it each year.

There are three vaccines for adults in Phase 3 trials, which together prevent 80% to 86% of severe RSV infections in people over 60. Trial data from Pfizer’s vaccine for older adults show it to be 86% effective at preventing severe disease. GSK’s vaccine is 83% effective in adults 60 years and older.

“There’s a general sense of optimism in the public health and vaccine professional communities that, this time around, these vaccines are going to be at least pretty good, and they will make their way through the regulatory process and be licensed, perhaps one or more of them as soon as next year,” Schaffner said.

Less Severe RSV Seasons Ahead

Before RSV vaccines hit the market, advisors to the FDA and Centers for Disease Control and Prevention (CDC) must meet to discuss their merits. This could happen within the next year or two. Schaffner said he expects the vaccines for older adults to be greenlit first.

Protection from the maternal vaccines will likely last up to six months, Schaffner said. This should be sufficient to protect babies when they’re most vulnerable. But Madhavan said the maternal vaccine is intended to be administered in the later stages of pregnancy, meaning babies born prematurely may miss out on protection.

Experts believe a vaccine that is administered directly to children may be necessary for longer-term protection, especially for kids with heart abnormalities and other medical conditions. Right now, at least two vaccines designed for kids are in Phase 1 clinical trials.

In coming years, RSV vaccines could be given routinely to people of all ages, much like the flu vaccine is, Schaffner said. With more population immunity, hospitals filled with RSV patients could soon be a thing of the past.