In recent weeks, pediatric hospitals in the United States they sounded the alarm: Their beds have been filled with young patients who have difficulty breathing and are in dire need of oxygen. This year the culprit is not the coronavirus, but the respiratory syncytial virus, better known as RSV.
RSV is not a new pathogen. The virus it infects approximately 64 million people annually Worldwide. But presents a particularly high risk for adults over 65 and children, who are more likely to require hospitalization. Worldwide, RSV causes approximately 160,000 deaths per year, including more than 100,000 children under the age of five. There is still no vaccine for the disease or any treatment available for general use.
But there are solutions on the way. Experts say that by the end of the year a treatment with monoclonal antibodies against RSV and that a vaccine could be launched in time for the RSV 2023 season.
“This could be a huge global game changer,” he says. Keith Klugmandirector of the pneumonia program Bill and Melinda Gates Foundationwhat finance Pfizer’s maternal vaccine candidate.
Here’s what you need to know about RSV, why cases are so high right now in the US, and why experts say these new advances are so promising.
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What is RSV?
According to According to the U.S. Centers for Disease Control and Prevention (CDC), RSV is a respiratory virus that is spread primarily through coughing, sneezing, and other forms of close contact. It is also seasonal: in the United States, RSV peaks in the winter months. Anyone can get or spread RSV, but people with healthy immune systems often only have mild cold-like symptoms.
Older adults with weakened immune systems have a harder time avoiding the virus, as do young children, whose still-developing immune systems have never been exposed to the pathogen. They are more prone to severe RSV infections, which can include symptoms such as dehydration and shortness of breath.
“RSV was unequivocally the leading cause of severe respiratory disease in infants and young children” before the advent of COVID-19He says Kathleen Neuzil, director of the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine. Young children are also particularly vulnerable because their airways are narrow: among children younger than one year, RSV is the leading cause of bronchiolitis, inflammation of the airways of the lung.
(Related: Is the COVID-19 pandemic already over?)
Why are cases on the rise?
It is not unusual for the United States to have so many cases in an RSV season, but it is unusual for RSV to increase this way at the start of the year. Neuzil suspects that COVID-19 is to blame: “COVID-19 has devastated the seasonality of our respiratory viruses.” Now that many people no longer wear masks habitually, experts hypothesize that viruses have started circulating out of season simply because people are more vulnerable to infection after two years without getting sick.
Neuzil says it’s unclear whether this change is permanent or whether RSV will eventually return to normal. normal seasonal trend, which begins in mid-September but peaks from late December to mid-February. It also remains to be seen whether the current hike represents the peak of this year’s RSV season or if the worst is yet to come.
(Related: Why does the coronavirus not affect children so much? These are some theories)
Why don’t we already have an RSV vaccine?
Researchers have spent decades trying to prevent RSV deaths. A particular effort to develop a vaccine during the 1960s was a colossal failure: made children sick instead of protecting them.
Bill GruberPfizer’s senior vice president of vaccine research and clinical development, says it was clear at the time that the goal was to “attack the commercial part of the virus,” which is the protein that allows the virus to fuse with the membrane of a human lung cell.
But the pivotal breakthrough came in 2013, says Gruber, when scientists discovered they needed to stabilize the viral protein used in the vaccine to keep it in its pre-fusion form. This is the idea behind most of the treatments currently under development.
What new RSV treatments are in development?
The most advanced RSV treatment is Nirsivamab, a monoclonal antibody developed by AstraZeneca. Given to babies by injection at birth or soon after, Nirsevimab delivers RSV antibodies directly into the bloodstream, allowing their immune systems to neutralize the virus and prevent it from replicating.
In March, a Phase 3 clinical trial showed 75% effectiveness in protecting children from lower respiratory tract infections severe enough to require medical attention. In early October, the World Health Organization’s Strategic Advisory Group of Experts on Immunization (SAGE) reviewed clinical trial data and reported that regulatory clearance is “forthcoming”.
Neuzil (a member of SAGE and its RSV vaccine technical advisory group) says the treatment could be authorized by the U.S. Food and Drug Administration in late 2022.
What about RSV vaccines?
According to Neuzil, there is a strong pipeline of RSV vaccine candidates Developing. But the first that could cross the line is Pfizer’s maternal vaccine, designed for pregnant women. The idea of this vaccine is to protect babies even before they are born by vaccinating the mother, who produces antibodies which are then passed to the fetus through the blood.
(Related: Why vaccines are still imperfect after decades of research)
In April the year she studies Phase 2b clinical trials have shown that Pfizer’s vaccine produced a high level of antibodies, which it’s worth it Revolutionary designation of the therapy by the FDA, which means the agency plans to accelerate vaccine development and review. Gruber says it is “very likely” that officials overseeing the trials will allow Pfizer to conclude them by the end of this year. Klugman of the Gates Foundation says FDA approval may come as early as 2023.
“This is something I’ve been waiting for my entire professional life,” says Gruber. “We are producing the right kind of antibody, so I think we are in a very good position to be successful.”
Meanwhile, Pfizer’s phase three studies best results among seniors showed 85% effectiveness. And there are other candidates for RSV vaccines that aren’t far behind. Some of these candidates contain adjuvantsor substances that increase the immune response, which, according to Neuzil, are not ideal for use during pregnancy.
How can people be protected now?
“It’s very exciting what we’re seeing with the new RSV vaccines and antibodies, but it won’t help children this winter,” Neuzil says. He recommends that people continue to take precautions such as wearing masks, especially if they spend time with infants or the elderly, who are particularly vulnerable to severe RSV.
“We’re getting closer, but this year we won’t get there,” he says. “So it’s very, very important to be very careful.”
