Why Isn't There An RSV Vaccine?

In a press release Pfizer says its maternal shot was 69% effective in preventing severe RSV infection in infants 0-6 months.
Posted at 4:33 PM, Dec 08, 2022

Parents of some of the nation’s youngest are stuck in the same concerning scenario.

"I'm panicking, crying, that's a scary feeling. You don't know what’s happening in that moment," said Laykin Weaver, a parent with a sick child.

"She was coughing a lot and had a really runny nose, so we took her in to the doctor and they tested her and said RSV," said Cynthia Layton, a parent with a sick two-month old. 

"As we were sitting in the waiting room it was little kid after baby after baby with the same symptoms," said Shauntel Pinnick, another parent with a sick child. 

Their children one of the two million kids under five who get infected with respiratory syncytial virus, or RSV, each year. The vast majority of cases are mild, but i’s the leading cause of hospitalization in infants. What is causing new concern is the rate of infections dramatically rising earlier than years past. 

"We've had a lot of young children who have not yet experienced their first infection. This RSV virus has taken advantage of all these susceptible children and has suddenly started to spread among them," said Dr. William Schaffner, a professor of Preventive Medicine in the Department of Health Policy and professor of Medicine in the Division of Infectious Diseases at the Vanderbilt University School of Medicine.

Doctors say RSV symptoms are similar to the common cold. But the virus can lead to more severe symptoms, especially in infants and young children. And unlike the flu or COVID, there is no approved vaccine to protect young kids against RSV. Why? 

"Science moves in a very deliberate way, and it's taken a while for us to develop a vaccine," said Schaffner. 

It’s a target scientists have aimed at for over half a century. Early RSV vaccine attempts in the 1960s led to disaster. In 1966, a clinical vaccine trial in Washington, D.C. failed. Scientists made the shot with inactivated virus that ended up making infants' cases more severe when exposed to RSV, and two young children died. Scientists struggled for decades to find out why the shot failed. 

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"Even though science was advancing, nobody wanted to go near the development of an RSV vaccine," said Schaffner. 

That was up until 2013, when National Institutes of Health scientists made a crucial discovery around the elusive fusion glycoprotein, or F-protein. This is what attaches the virus to cells in the immune system. What makes it tricky to defeat is its ability to change shape. 

Now scientists believe they know how to cut off the F-protein before it fuses with a cell. It would set up the immune system to read and defeat the protein. Vaccine makers are using that discovery and are nearing a breakthrough, looking at vaccinating adults instead of infants. 

Carlos Blanco is helping run vaccine trials for drug makers Moderna and Bavarian Nordic. The groups are studying shots in adults 60 and older. Like infants, older adults are at higher risk of a hospital stay if they get RSV.

"We're making really significant progress with the RSV vaccine," said Blanco.  

 Drug maker Pfizer is testing its potential vaccine in pregnant women late in their third trimesters. Pregnant mothers get other vaccines too, for diseases like the flu and whooping cough. 

"Some of that protection cross the placenta, protecting that newborn through the first several months of life before we can start vaccinating the newborn," said Schaffner.  

In a press release Pfizer says its maternal shot was 69% effective in preventing severe RSV infection in infants 0-6 months, when children are most at risk. 

Pfizer has submitted for FDA approval for its RSV shot for adults 60 and older. In a press release, the company says it is expediting the review process. We could expect a final decision by May of 2023. 

Industry officials are optimistic an approved vaccine is near though hospitals now face a surge in patients. 

"It's hard to offer a guess but I would say definitely within 12 to 16 months we should have a vaccine available," said Blanco.  

"I don't know that it'll be next season, but I do think within the next couple of years," said Dr. Melissa St. Germain, a pediatrician at Children's Hospital and Medical Center Omaha. 

It’s a glimmer of hope for doctors fighting RSV in the future, while doctors today care for those suffering now.