Culminating a push led nationally by University of Rochester Medical Center researchers, Pfizer recently won Food and Drug Administration approval for an RSV vaccine.
RSV is short for respiratory syncytial virus. Syncytial, pronounced sin-sish-ul, refers to a peculiarity of the virus that causes infected cells to conjoin.
Edward Walsh M.D., who has researched RSV vaccines, says that effect occurs in the lab but is rarely seen in infected humans.
RSV infections in humans can range from asymptomatic and moderate to fatal. RSV is the single most common cause of infant hospitalizations. For infants in the first few months of life, premature babies, older adults and people with compromised immune systems, RSV can be fatal.
Researchers including Walsh, who has investigated RSV since the 1980s, have pursued a vaccine to rein in RSV for decades. The FDA green lighted Pfizer’s RSV vaccine on the heels of its approval of an RSV vaccine developed by Glaxo Smith Kline. Moderna awaits approval of its RSV vaccine.
The Pfizer, GSK and Moderna vaccines have slightly different mechanisms but are roughly equally effective, Walsh says.
A UR professor of medicine, Walsh heads a vaccine lab at Rochester Regional Health’s Rochester General Hospital.
Walsh was national leader for Pfizer’s Phase III RSV vaccine trial. He and Ann Falsey M.D, co-director of URMC’s Vaccine Treatment and Evaluation Unit, this year co-authored a New England Journal of Medicine study outlining the results of the Pfizer RSV vaccine’s Phase III clinical trial.
Annaliesa Anderson, Pfizer chief scientific officer for vaccine research and development calls FDA approval of the long-sought RSV vaccines “a monumental step” and the Phase III trial Walsh led “critical.”
Some 37,000 individuals took part in the clinical trial.
“We are extremely grateful to the clinical trial participants (and) study investigator teams…for their roles in making this vaccine available,” Anderson says.
At the height of the of the COVID pandemic in 2021, RSV along with the flu virtually disappeared, Walsh says. Arriving at an atypical season RSV returned in the summer of 2022.
The relative scarcity of RSV was good news for at-risk populations and for overburdened hospital staff. But cases as the Phase III trial came into its final stretch it posed some difficulties researchers, says Walsh, “but we plowed ahead.”
For RSV vaccine researchers, the FDA approval is not the end of the road.
Pfizer’s and GSK’s RSV vaccines are currently approved for older adults. Walsh, who has worked with Pfizer on various vaccines including an in-development mRNA flu shot, says plans trials to test its RSV vaccine’s safety and effectiveness on other age groups like 18- to 60-year-olds and two-to 18-year-olds.
The French drug maker Sanofi, has been investigating an RSV shot for pregnant women and newborns.
If an RSV vaccine could be shown to be safe for pregnant women, mothers to be could get injections in order to pass immunity to their babies while still in the womb. Walsh says that would provide critical protection for infants in the first few months of their lives, when they are most vulnerable to the virus. Whether premature babies could be vaccinated is a tricky question.
Clinical-trial results have shown Pfizer’s and GSK’s vaccines to be more than 80 percent effective. RSV shots will not provide lasting immunity, however, and will have to be renewed every one or two years, Walsh predicts.
While clinical trials have shown the currently approved Pfizer and GSK RSV shots to be highly effective, Walsh has a word of warning. How effective the vaccines will prove to be for the highly vulnerable populations that need them most will only be known as the vaccines go into general use.
After decades of running clinical trials, “it’s been my experience that people who volunteer for vaccine clinical trials as a rule are pretty healthy,” Walsh notes. Results among sicker and more vulnerable populations might not match trial results, he cautions.
Will Astor is Rochester Beacon senior writer. The Beacon welcomes comments and letters from readers who adhere to our comment policy including use of their full, real name. Submissions to the Letters page should be sent to [email protected].
I have first hand experience with people who volunteer for vaccine clinical trials. This person volunteered for a trial and it went beyond bad. They dropped this person from the study and stated that the problems experienced were not the result of the vaccine study. This person didn’t take no for an answer. Said person studied and took it to the physicians in charge. While they didn’t take responsibility, they settled by providing free health care. Getting the picture here. The real interesting thing is that when a person drops out due to issues on the first round of any study, that person is no longer in the study and the results are not part of the study. What a great way to assure the success of a vaccine trial. Those who are involved with these studies know that this is indeed the case. I have written a paper on this. In the case I am referring to, it was tragic.