RSV Is Surging: What We Know about This Common and Surprisingly Dangerous Virus

RSV Is Surging: What We Know about This Common and Surprisingly Dangerous Virus

As flu season ramps up, experts weigh concerns over another possible covid surge , hospital beds are already crowded with patients with the respiratory syncytialvirus (or RSV) Although many people don’t know about RSV, almost everyone has experienced it at least once, according to Anthony Flores (chief of pediatric infectious diseases at University of Texas Health Science Center in Houston) and Children’s Memorial Hermann Hospital physician. RSV is the leading cause of bronchiolitis–inflammation of the lung’s small airways–in infants, and the virus is so common that nearly all children have encountered it by their second birthday.

” It’s so widespread,” Flores said. “Even adults are repeatedly exposed to it over time, so it develops some immunity to it.” RSV is typically seen in healthy adults and children as a common cold with symptoms similar to those caused other “common cold viruses” such as rhinovirus and adenovirus. It isn’t always harmless. RSV costs the U.S. more than $1 billion each year in health care costs and lost productivity, and it can be particularly dangerous for newborn babies and adults older than age 65.

“As we have come to learn, particularly gradually over the last 15 years, this is a virus that annually produces probably about as much illness in adults as does influenza,” says William Schaffner, a professor of medicine at Vanderbilt University Medical Center and medical director of the National Foundation for Infectious Diseases. This is because our immune system age with us. Flores states that as we age, our immune system becomes less effective.

The good news is that RSV vaccines will soon be available. In fact, Pfizer just announced this week that its maternal RSV vaccine–given during pregnancy so that antibodies are transferred through the placenta to the fetus–was 82 percent effective at preventing severe RSV in babies through three months old. RSV is a common virus that people will encounter every year, until the U.S. Food and Drug Administration approves vaccine.

What is RSV, and what are its symptoms?

RSV is an RNA virus made up of 11 proteins, similar to influenza A, another RNA virus whose genes encode the same number of proteins. It causes inflammation in the throat, nose, and lungs. According to the National Foundation for Infectious Diseases Inflammation in the airways is caused by the body sending immune cells to virus-infected cell to fight the disease.

Symptoms include a runny or swollen nose, decreased appetite, wheezing, coughing, and sometimes mild fever. However, fever is more common in infants than older adults. The symptoms usually appear within four to six days of infection. It can take up to two weeks for them to clear.

How can RSV be transmitted?

RSV spreads primarily through respiratory droplets from coughing, sneezing and kissing (transmission by airborne droplets, or aerosols, has not yet been shown). The virus can survive for hours on hard surfaces such as tables and crib rails. These “fomites”, which are more common for RSV, are more common than for COVID. RSV is usually contagious for three to eight days.

The basic reproduction number, or R0, for RSV is estimated to be around 3, which means a single infection of RSV will lead, on average, to three other infections.

How severe is an RSV-infection?

RSV is a nuisance for the average person, Flores states. Flores states that RSV is similar to a common cold for most people, including children over two years old and healthy adults. It may cause a slight cough, runny nose, or mild fever, but it is usually quickly over .”

But infants younger than six months, and especially those less than two months, are more likely to contract RSV. Flores states that this age group has the highest hospitalization rates, with some children being admitted up to four times more than others. It’s basic physics. He says that it all has to do with their airways’ size. Their airways aren’t large enough to allow airflow, even with all the inflammation from the immune system’s response.

Even then, only about 1 to 2 percent of children under six months with RSV need hospitalization (usually for a couple of days), and death is rare. An estimated 58,000 U.S. children are hospitalized with RSV each year, and the virus kills about 100 to 500 U.S. children under five each year. (Since the pandemic began, COVID has killed more than 560 children under five, according to the U.S. Centers for Disease Control and Prevention.) Premature babies and people with underlying heart or lung conditions are at greatest risk of complications and hospitalization. Premature infants have a lower ability to handle the virus-related inflammation and their lungs are less developed. In fact, children who meet strict criteria for being at highest risk are recommended to receive the preventive antibody medication palivizumab as an injection into the thigh muscle once a month when RSV is circulating.

Adults older than age 65 are also at risk of severe RSV, although public health officials have only begun to recognize the threat to older adults in the past decade. Every year an estimated 177,000 older adults are hospitalized with RSV, and about 14,000 die from it. For comparison, influenza kills anywhere from 21,000 to more than 44,000 adults older than 65 each year.

Another population that is at greater risk of complications from RSV is the immunocompromised. This could be due to an underlying condition or medication that suppresses their immune system. For example, organ transplant recipients may take medication to suppress their immune system and prevent rejection. Many drugs used to treat autoimmune diseases also weaken the immune systems.

Why are cases on the rise now?

Historically, RSV season was so predictable that children’s hospitals planned staffing around the time. It usually ran from November to April, with the highest peak in January and February depending on local conditions. The pandemic changed everything. With many people staying home, social distancing, washing hands and wearing masks for most of 2020 and into 2021, RSV–like influenza–never really arrived, and its seasonality has been out of whack ever since.

“We had a sudden surge in RSV last summer,” Flores said. “It was a puzzle at first, but then it became epidemiologically understandable.” Most children get RSV in their first year and half of life. They develop immunity as they heal. Although the immunity doesn’t last for very long, it is enough to allow for subsequent infections to be less severe. A whole generation of children was never exposed to RSV because of the social distancing and concealing. So as society began opening back up in the summer of 2021, all of them were exposed at once, and RSV roared back like it was Christmas in July.

” We saw more severe reactions and more hospitalizations. I believe it was because we had more children who had never been exposed. That summer surge eventually settled down, but fast-forward to 2022, and although it’s later in the year, something similar is happening.

On the one hand, current pediatric hospitalizations at Flores’s and other hospitals aren’t as high as they would be during midwinter’s RSV peak. It’s not yet midwinter, but that’s not the problem. As flu cases rise, both pediatricians and public-health experts are asking the same question: “Are there going to be another surge in COVID later in the year and then a ‘tripledemic? Flores answers. “That’s the biggest worry.” Flores does not believe that a triple surge would necessarily result in more deaths, but it would be a significant burden on the healthcare system that many people aren’t ready for.

Is there a vaccine against RSV?

There is no approved RSV vaccine yet, but there likely will be soon. Scientists have been working on such a vaccine for half a century, but a disastrous trial in the 1960s resulted in the deaths of two toddlers who caught RSV after receiving the vaccine. The disease was more severe in those who had been vaccinated. This was why there was not much progress. Fortunately, one of the same scientists whose team determined the spike-protein mRNA code for the COVID vaccines, Jason McLellan of the University of Texas, solved the RSV vaccine problem with virologist Barney Graham, then at the National Institutes of Health, about decade ago. This work is now complete.

Several pharmaceutical companies began vaccine trials with McLellan’s protein in 2017, and the first successful phase III (late-stage) results came this year. Pfizer’s vaccine was 86 percent effective, and GSK’s was 83 percent effective in adults 60 and older. Between those vaccines and Pfizer’s recent maternal RSV vaccine news, Graham, who is now retired from the NIH, expects to see at least one RSV vaccine approved by the end of 2023, if not sooner.

How does RSV get treated?

There is no medication that can treat RSV. The treatment is primarily supportive care for symptoms like fever and congestion. People with difficulty breathing may be given a breathing tube, or supplemental oxygen via a mask or nose tube. Flores states that although the American Academy of Pediatrics used recommend steroids for infants in the past, there are conflicting data on how effective they work.

There are two reasons that RSV doesn’t have a treatment. It’s difficult to find effective drugs for respiratory viruses infections. Most of the four antivirals available for flu, for example, are fairly new and have limited effectiveness unless given early after infection. Second, RSV is a rare disease that causes death in children. Therefore, therapeutics are not as important as drugs for other conditions. The pipeline for RSV treatment has been bolstered by the recent knowledge of how many adults are affected by RSV and the advancements in monoclonal antibody technology.

The drug furthest along is nirsevimab, which was 75 percent effective in healthy infants in a phase III trial and has been shown to be safe in premature infants as well. FDA approval could be forthcoming in the next year or later.

What should someone do if they think they or a family member has RSV?

You won’t be able to tell if you have RSV, as it will feel just like any other cold. Flores advises that you do “all the things we learned in the pandemic” if you are sick. This includes wearing a mask, good hand hygiene, covering your mouth if you cough or sneeze, and, if possible, working from home. Many people won’t or can’t stay home from school or work with just a cold, though, so wearing a mask can at least protect others around you while you’re sick, especially those at higher risk for complications. If there’s anything we learned from the way flu and RSV basically disappeared in 2020, Flores says, it’s that masking obviously works.

When should someone with RSV go to the hospital?

As with any other respiratory condition, difficulty breathing is the most important sign to seek medical attention. Parents should also take infants under six months to the hospital if their child is unable to lie down without difficulty breathing, if they are sleepier than usual, or if they are difficult to wake from sleep.

What can one do to protect vulnerable people from RSV?

Infants and young children who were born premature or who have weakened immune systems, chronic lung disease, congenital heart disease or a neuromuscular disorder may qualify to receive the drug palivizumab. Palivizumab can be very expensive and is in limited supply so it’s reserved only for those who are most at risk. When the RSV season was more predictable, at-risk infants would begin receiving palivizumab in late fall, but when RSV’s seasonality shifted in 2021, state public health authorities convened to ensure the drug would become available when cases began rising.

For others at risk, including infants without underlying conditions, older adults and immunocompromised individuals, the same protections they take against COVID are also effective against RSV, as the low rates of RSV in 2020 showed. Flores states that when we see such surges, [vulnerable persons] are urged to be more cautious. To prevent COVID, Flores recommends that sick relatives avoid visiting, that you wash your hands frequently, and that you wear a mask outside to protect yourself from exposure to other seasonal respiratory viruses such as flu and RSV. And of course, Flores says, everyone eligible for a flu vaccine and COVID vaccine should ensure they’re vaccinated and boosted to reduce the risk of developing multiple infections at the same time.

ABOUT THE AUTHOR(S)

    Tara Haelle is a Texas-based science journa

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