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By Dana G. Smith in the NYT

Respiratory syncytial virus is the leading reason for hospitalization among infants in the United States. Between 58,000 and 80,000 children under the age of five, the majority of whom are less than a year old, are hospitalized for it every year.

R.S.V. also results in 60,000 to 160,000 hospitalizations and 6,000 to 10,000 deaths annually in Americans over the age of 65. (For comparison, flu caused about 171,000 hospitalizations and 16,000 deaths in older adults during the 2019-2020 flu season.)

Despite the harm caused by the disease, R.S.V. historically has not received as much attention as the flu or Covid-19. That’s starting to change, in part because the serious consequences of R.S.V. were on full display last winter with the so-called “tripledemic,” when the virus overwhelmed hospitals alongside the flu and Covid.

Coinciding with rising awareness about the risks of R.S.V., there are finally tools available to prevent severe infections in both infants and older adults. In May, the Food and Drug Administration approved two vaccines for adults 60 and up, in July it approved a monoclonal antibody therapy to protect infants and toddlers who are at high risk for severe disease, and in August it ruled that one of the vaccines could be given to pregnant mothers in order to protect their newborns.

Here’s what to know about the different options, who should get them and when.

Vaccines for adults

The two adult vaccines, which were created by Pfizer and GSK, are very similar, both in terms of how well they protect against symptomatic R.S.V. infection and in their side effects. They also work the same way biologically — targeting a protein the virus uses to fuse to human cells — and were developed based on the same decade-old scientific discovery, which is why they’ve emerged at the same time.

In clinical trials, the Pfizer vaccine, called Abrysvo, was 89 percent effective at preventing lower respiratory symptoms (such as cough, shortness of breath or wheezing) in the first R.S.V. season after vaccination, while the GSK vaccine, called Arexvy, was 83 percent effective. There weren’t enough people in either trial to determine whether the vaccines also helped reduce hospitalizations and deaths, but experts anticipate that they will.

The vaccines were somewhat less effective at preventing disease in the second R.S.V. season after people received a shot. However, experts say that R.S.V. doesn’t mutate in the same way that influenza and SARS-CoV-2 do, so there shouldn’t be a need to update the vaccine or re-dose people every year.

“At least in terms of the more severe symptoms from the infection, it did not seem to diminish over the two-year period appreciably,” said Dr. Edward Walsh, a professor of medicine at the University of Rochester Medical Center, who led the Pfizer clinical trial. “This would suggest that right now, we’re probably looking at a vaccine that is not given any more frequently than every two years.”

Out of the roughly 38,000 people who received either vaccine, 20 experienced atrial fibrillation and six developed neurological complications, including encephalomyelitis and Guillain-Barré syndrome, in the weeks after vaccination. More common side effects were fatigue, fever and muscle pain at the site of the injection.

Rather than recommend the vaccines outright to everyone 60 and older, the Centers for Disease Control and Prevention advised that people talk to their doctors when deciding whether to get the shot. They included this extra step in part because of the potential for these severe, albeit very rare, side effects.

It’s about weighing the benefit versus the risk, said Dr. Tochi Iroku-Malize, the president of the American Academy of Family Physicians. She and the A.A.F.P. support the federal recommendation that older adults get the vaccine after consulting with “their physician to make sure that this is the right thing for them.”

“Most adults who get infected with R.S.V. usually have mild or no symptoms,” she added. “But some adults may have more severe symptoms,” usually because they have an underlying condition such as chronic obstructive pulmonary disease, asthma, heart disease, diabetes, kidney disease or a compromised immune system. People with these conditions may benefit more from receiving the vaccine.

The vaccines will be available at doctors’ offices and some pharmacies, including Walgreens and CVS, this fall. R.S.V. season typically begins in October, and people are encouraged to get the shot before it starts. The R.S.V. vaccine is safe to get at the same time as the flu shot, Dr. Walsh said, but there isn’t available data yet on receiving it and the Covid vaccine simultaneously.

Monoclonal antibodies for infants

While vaccines teach the immune system to produce antibodies against a specific disease, monoclonal antibodies provide an infusion of prefabricated antibodies — but their protection is more temporary. For babies whose immune systems are still developing, that temporary immunity could make a big difference.

A new monoclonal antibody therapy developed by AstraZeneca, called nirsevimab, was approved earlier this year to protect infants against severe R.S.V. In a clinical trial, the drug was about 77 percent effective against both hospitalizations and cases of R.S.V. requiring a doctor’s visit. Side effects were mild, with a rash at the injection site being the most common.

The C.D.C. recommended that all infants who are less than 8 months old at the start of R.S.V. season receive nirsevimab. Children between the ages of 8 months and 19 months are also recommended to get the shot if they have an increased risk for severe disease. That includes not only children who are immunocompromised or have pre-existing lung conditions, but also American Indian and Alaska Native populations. Babies should be able to receive the monoclonal antibody therapy at their pediatrician’s office, and some hospitals may offer the shot to newborns delivered during R.S.V. season.

Dr. Ruth Karron, a pediatrician and professor of international health at the Johns Hopkins Bloomberg School of Public Health, said that she “completely concurs with” the C.D.C. recommendations. “R.S.V. is the No. 1 cause of hospitalization for children under a year of age,” she said. “I think it will make a profound difference in the health and well-being of children.”

Babies over 8 months old can also become ill with R.S.V., but “they’re far less likely to have to be in the hospital or far less likely to get severely ill,” said Dr. Coleen Cunningham, the chair of pediatrics at the University of California Irvine and pediatrician in chief of Children’s Hospital of Orange County.

That’s because the youngest infants’ airways “are just smaller, so any little bit of swelling in that airway has a bigger impact on how well they can breathe,” Dr. Cunningham said.

A vaccine for pregnant women

The F.D.A.’s final R.S.V.-related decision this year was to approve giving the Pfizer vaccine to pregnant women so they will pass on antibodies to their babies through the placenta.

A clinical trial found that, for mothers who were vaccinated between weeks 24 and 36 of their pregnancies, the shot was 82 percent effective at preventing severe disease in infants in the first three months after birth. That dropped to 69 percent protection six months after birth.

The most common side effects of the vaccine were muscle pain, headache and nausea. Cases of severe side effects were slightly higher in the vaccine group compared to the placebo group, including pre-eclampsia in the mothers and low birth weight and jaundice in the infants. Preterm birth was also more common, occurring in 5.7 percent of the vaccine recipients compared to 4.7 percent of the placebo recipients. The F.D.A. stated that it couldn’t “establish or exclude a causal relationship between preterm birth and Abrysvo,” but they advised that the vaccine be given to women between 32 and 36 weeks of pregnancy to minimize any potential risks.

Now that both the monoclonal antibodies and prenatal vaccine are approved, pediatricians and obstetricians will have to work together to recommend which patient should receive which treatment. Dr. Karron said that healthy babies should not receive both the vaccine and monoclonal antibodies, “not for safety reasons,” but because it would be “a waste of resources.”

Dana G. Smith is a reporter for the Well section, where she has written about everything from psychedelic therapy to exercise trends to Covid-19. More about Dana G. Smith

From Yale Medicine – thanks to Ed M.

This winter, when the usual sneezing, wheezing, coughing, and fevers start up, there will be extra protection for people at high risk from at least one common illness. Respiratory syncytial virus (RSV) causes mild cold symptoms in most people but can lead to hospitalization and even death in older people and babies. But now, two new RSV vaccines aimed at older people and a monoclonal antibody for children up to age 2 could become available as soon as late summer or early fall.

“A lot is changing for RSV,” says Scott Roberts, MD, a Yale Medicine infectious diseases specialist. “There have been attempts to make a vaccine for decades, and they have failed for a variety of reasons.”

One turning point came with the investigation of an RSV protein called “RSV fusion (F)” that provided potent stimulation to the immune system—research that paved the way to clinical trials showing positive results. “Now, it looks as though we may have two vaccines for adults in time for the next RSV season—and there are more potential RSV therapeutics in the pipeline,” Dr. Roberts says.

Older people start to lose immunity as they age—they’re unable to fight off infections, such as RSV, as well as they did when they were younger, explains Dr. Roberts. Plus, the COVID-19 pandemic may have led to several years of lost immunity since RSV wasn’t really circulating during that time. However, by November 2022, RSV was surging in children, and the RSV hospitalization rate for older adults was 10 times higher than usual for that time of year. More people were becoming infected, probably as a result of more in-person, maskless contact, he adds.

In June, the Centers for Disease Control and Prevention (CDC) confirmed the Food and Drug Administration (FDA)’s approval of the two vaccines for older people, specifying that those ages 60 and older “may” get them based on “shared clinical decision-making,” meaning they may receive a single dose based on discussions with their health care provider about whether RSV vaccination is right for them.

In July, the FDA approved another preventive option, a monoclonal antibody called nirsevimab (brand name Beyfortus™). In August, the CDC signed off on the drug for all infants up to 8 months old, born during—or entering—their first RSV season, and for a small group during their second season who are between 8 and 19 months old and at high risk for severe disease (including children who are severely immunocompromised).

Dr. Roberts and Thomas Murray, MD, PhD, a Yale Medicine pediatric infectious diseases specialist, answered questions about the coming options for older adults and kids.

What is RSV, and why is it a threat to some people?

RSV is a common respiratory virus that usually causes mild, cold-like symptoms. It’s a seasonal illness, typically starting in the fall and peaking in the winter. Once a person is infected, the treatment is supportive care, such as over-the-counter medications and maintaining hydration. Most people get better in a week or two.

But when RSV makes its way down into the lungs, causing lower respiratory tract disease (LRTD), it can cause vulnerable people, including those 65 and older, to develop life-threatening complications, such as pneumonia, and make existing conditions, such as asthma, congestive heart failure, and chronic obstructive pulmonary disease (COPD), worse. Each year, this leads to 60,000 and 160,000 RSV hospitalizations in adults 65 and older, and 6,000 to 10,000 deaths.

Babies are susceptible to RSV because their immune systems are not fully formed, adds Dr. Murray. “Their lungs aren’t fully developed. So, if the virus gets into the lungs of really young babies, they can develop respiratory problems and need support, such as supplemental oxygen, to help them breathe.”

In children younger than 5, there are approximately 2.1 million RSV-related outpatient visits a year, 58,000 to 80,000 hospitalizations, and 100 to 300 deaths.

How effective are the RSV vaccines for older adults?

Both vaccines for older adults use traditional platforms—similar to a flu shot (and not to be confused with the mRNA technology introduced by Pfizer-BioNTech and Moderna to prevent COVID-19). The RSV vaccines work by introducing an inactivated RSV protein into the body, where it fuses to host cells and stimulates the immune system to recognize the actual RSV virus if/when it encounters it and help prevent severe disease.

Both vaccines performed well in clinical trials, according to data presented to the FDA. Arexvy™, developed by GSK, was the first to receive FDA approval—in early May—based on data from a trial conducted by the company in the U.S. and internationally. The ongoing trial is following participants through three RSV seasons. In late June, GSK reported an overall efficacy of 82.6% against lower respiratory tract disease during the first season, 77.3% for mid-season, and 67.2% over two seasons. Against severe disease, efficacy was 94.1% during the first season, 84.6% at mid-season, and 78.8% over two seasons.

The second vaccine, called Abrysvo™, from Pfizer, showed an efficacy of almost 89% against LRTD involving at least three symptoms in the first year after vaccination, and 78.6% mid-way through a second season in the data presented to the FDA. LRTD symptoms include new or increased cough, wheezing, sputum (phlegm) production, shortness of breath, and/or tachypnea (abnormally rapid breathing).

While data showed that one vaccination could be protective for at least two seasons, no determination has been made on how frequently the shots should be given.

Will there be an RSV vaccine available for children?

The FDA is considering a vaccine that would be given to pregnant women, who would then pass the protection on to their fetuses.

Abrysvo, Pfizer’s vaccine for older people, was recommended to the FDA for this purpose by its advisory panel in May. If the FDA approves the shot, it would be given to mothers-to-be in their late second or third trimester of pregnancy to help them develop antibodies against RSV that would be passed along to the fetus—and it would continue to provide protection to the baby after delivery.

Clinical trials for the vaccine in this age group showed an 81.8% efficacy in preventing severe respiratory illness within three months after birth and 69.4% in the first six months of life. However, a few of the FDA advisors expressed concern over a slight increase in preterm births among women who got the shot—5.6% in vaccinated women compared to 4.7% in an unvaccinated group. (FDA officials said the difference was not statistically significant.)

What do we know about nirsevimab, the FDA-approved monoclonal antibody for infants and toddlers?

Nirsevimab, which was developed by Sanofi and AstraZeneca, is given in a single injection to the thigh. A Phase 3 clinical trial showed that nirsevimab reduced RSV-triggered lower respiratory tract infections serious enough to require medical care by 76.4% and cut RSV hospitalizations in healthy full-term and near-full-term infants by 76.8%.

The monoclonal antibody works differently than a vaccine. “When you’re injected with a vaccine, it causes your body to produce antibodies to protect you against whatever the vaccine is for,” Dr. Murray says. “The monoclonal antibody bypasses that step. Your body gets—in this case—a single kind of antibody directly injected into the bloodstream so that if you’re infected with that organism, the antibodies will bind to it and help you clear the infection.”

The antibody reduces hospitalization significantly, he adds. “Even if it doesn’t completely prevent disease, it can significantly reduce disease severity. This will be extremely helpful this year, especially after the RSV surge we had last winter,” he says. “And in the trials, there was no difference in adverse effects between the placebo and antibody groups.”

What if you are not an older person or an infant?

If you don’t fall into one of those categories and are otherwise healthy, you probably don’t need a preventive therapy, Dr. Murray explains. “Virtually every child has experienced RSV by the age of 2 and has immunity,” he says.

Older children, teenagers, and most adults have strong immunity from multiple exposures and rarely experience LRTD from RSV. “We want to make things available to the highest-risk patients first,” Dr. Murray says. “We’ll have to wait and see whether or not the vaccines will be approved for people at other ages with chronic underlying illnesses, such as serious heart or lung problems.”

Are there side effects from the vaccines or other concerns?

The CDC advisory panel expressed concerns about the clinical trial data to the point where they changed an initially strong recommendation to get the vaccine, if eligible, to one that says people over 60 “may” get an RSV vaccine based on a shared discussion with their doctors. For some, this may mean a discussion with their pharmacist. (The RSV vaccines will be covered by Medicare Part D and, thus, will be administered in pharmacies in many cases.)

One issue was that a few people in the trials developed Guillain-Barré syndrome in the days following the shot. Guillain-Barré is a rare disorder that causes muscle weakness and sometimes paralysis.

In addition, atrial fibrillation (an arrhythmia that can lead to blood clots in the heart) within 30 days of vaccination was reported in 10 participants who received Arexvy and four participants who received a placebo.

“One could argue that the benefits of these vaccines far outweigh the risks; for instance, the protection afforded against severe RSV disease is greater than the small risk of Guillain-Barré in this situation,” says Dr. Roberts. There will be continued monitoring for Guillain-Barré and other issues once the RSV vaccines become available, he adds.

Another issue was that most of the participants in the clinical trials were in their 60s, so there was little data on other high-risk groups, such as those over age 80.

Should you get the RSV vaccine if you’re eligible?

Both doctors say the benefits of the new vaccines for older adults outweigh the potential harms in cases where RSV could be life-threatening. They recommend them to all eligible older adults, particularly those with underlying health conditions, such as heart or lung disease, or weakened immune systems.

They also suggest that people who are vulnerable or could infect others who are at high risk take additional precautions this fall. Since RSV is spread through contact with contaminated surfaces, that includes washing hands often, keeping hands away from your face, avoiding kissing and other close contact with people who have cold-like symptoms, avoiding close contact with sick people, cleaning frequently touched surfaces, such as doorknobs and mobile devices, and staying home when you are sick. “All of these things will protect against RSV,” Dr. Roberts says.

According to the CDC, RSV vaccines may be given at the same time as other vaccines.