“This is potentially very exciting news,” says William Schaffner, MD, professor of medicine, in the division of infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee, who was not involved in the vaccine’s development. “RSV is the leading cause of hospitalization in young infants — if we could reduce that by 70 percent, that would an enormous boon,” he says. The rise in RSV, flu, and COVID-19 cases in recent weeks have many experts worried that the United States could soon be dealing with a “tripledemic” of the respiratory viruses. RELATED: How Babies Get RSV, and More Answers to Common Virus Questions Based on these positive results, the company will end enrollment in the study and submit an application for approval to the U.S. Food and Drug Administration (FDA) by the end of 2022, according to the statement. “I think it is very promising and likely will portend a successful FDA licensure for this maternally targeted vaccine,” says Amesh A. Adalja MD, senior scholar at the Johns Hopkins Center for Health Security in Baltimore, who was not involved in the research. Decreasing the rate of hospitalization in the first 90 days of life is a significant benefit as the youngest children are at the highest risk for severe RSV, he says.
RSV Can Be Dangerous for Infants and Older Adults
RSV is a common respiratory virus that usually causes mild cold symptoms such as runny nose, coughing and sneezing. Most people recover in a week or two, but RSV can be serious, especially for infants and older adults. In the United States, RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia in children under 1 year old. Each year, the virus leads to an estimated 2.1 million doctor visits and 58,000 to 80,000 hospitalizations in children under age 5, according to the Centers for Disease Control and Prevention (CDC). “Every year we see high levels of RSV cases among babies in the U.S., with some regions reporting hospital admission rates higher than normal this year,” said Eric A.F. Simões, MD, clinical professor in pediatrics and infectious diseases at the University of Colorado School of Medicine and Children’s Hospital Colorado in Aurora, in the press release. “A maternal vaccine with high efficacy that can help protect infants from birth could substantially reduce the burden of severe RSV among newborns through 6 months of age, and, if approved by regulatory authorities, will likely have a significant impact on disease in the U.S. and globally,” he said. Globally, RSV caused more than 100,000 deaths in children under 5 in 2019, with nearly half of these occurring in children younger than 6 months old, according to a study published in May 2022 in The Lancet.
Vaccine Works by Passing Protection From Mother to Baby
The phase 3 trial enrolled approximately 7,400 pregnant women, and participants were randomized to receive the vaccine or placebo during the late second to third trimester of their pregnancy. This trial was designed to prevent severe disease in newborns and infants by targeting pregnant women, explains Dr. Schaffner. The vaccine works through passive immunity — the women are protected by the vaccine, and then they pass the protection along to the infants via the placenta. The women were followed for safety through vaccination and for six months after delivery, and the infants were followed for at least one year for efficacy and safety; over half of the infants were followed for two years. In addition to preventing severe disease in infants, the virus also cut RSV-caused doctor’s visits in infants by more than 50 percent compared with placebo. Although this didn’t meet the target outlined at the start of the trial, Pfizer’s researchers still consider the result clinically meaningful.
Experts Predict Multiple RSV Vaccines Will Be Available Soon
Researchers have worked for decades on preventative options for RSV, and the last five years has seen a flurry of progress. Although no RSV vaccine has been approved (yet), there are more than 30 preventive options are on the horizon, and nine of those are in advanced trials, according to a paper published in August 2022 in The Lancet. Last month, GSK reported that its RSV vaccine was 83 percent effective against serious illness in adults older than 60; the FDA is expected to begin its review of the vaccine by the end of the year. In August, Pfizer also reported positive results of their RSV vaccine in a phase 3 trial in adults age 60 and older. “Within a year there will likely be multiple RSV vaccines on the market targeting both pregnant women and high-risk adults,” says Dr. Adalja.
RSV Prevention
Take precautions to protect yourself and your family by following tips from the CDC:
Cover sneezes and coughs with a tissue or upper shirt sleeve — not your hand.Wash your hands often.Clean high touch surfaces like doorknobs and phones.Avoid touching your child’s face with unwashed hands.Avoid close contact with sick people.
