Comment Pfizer announced Tuesday that its maternal RSV vaccine, given during pregnancy, protects infants from developing severe symptoms in the first six months after birth — a critical window of vulnerability. The company plans to file for approval of the vaccine before the end of the year, with the hope that the vaccine could be the first to help protect infants against RSV — the respiratory syncytial virus — as soon as next year. winter. The data were announced in a press release and have not yet been published or peer-reviewed. But it offers a glimmer of good news in the midst of a violent and early RSV season that has contributed to a wave of respiratory illnesses overwhelming many pediatric hospitals. “We are very optimistic that everything can be done in time to get mothers vaccinated before the next RSV season,” said Annaliesa Anderson, chief scientific officer of vaccine research and development at Pfizer. “We are about to enter a very heavy RSV season. We see hospitals filling up. Everyone appreciates the urgency that can really help prevent this.” RSV is a common respiratory illness and most people experience it as symptoms similar to the common cold. But in young infants, whose airways are smaller, the virus can be life-threatening — and is the leading cause of hospitalization for babies. Decades of fear and failure in the hunt for an RSV vaccine. Now, success. Unlike vaccines given directly to infants, the Pfizer vaccine provides protection through an indirect route. Antibodies are naturally passed on to infants during pregnancy, so maternal vaccination is one way to give babies a temporary, but immediate, shield of immune protection. Influenza, diphtheria, tetanus and pertussis vaccines are also given as maternal vaccinations. The Pfizer vaccine, given in the early third trimester, was 69 percent effective after birth in preventing severe cases of illness requiring medical attention over six months. It was even more effective in the first three months after birth, possibly reflecting antibody levels that naturally decline over time. The researchers also measured whether the vaccine prevented medical visits in infants caused by RSV, including cases that were not severe. These results did not reach statistical significance, but suggested that the vaccine could cut medical visits due to RSV in half during the first six months after birth. The company said there were no major safety concerns for babies or vaccinated people, but that the data would be carefully scrutinized by regulators. The trial involved 7,400 pregnant women and the infants were followed for at least a year. Barney Graham, a vaccine expert at the Morehouse School of Medicine whose work with Jason McLellan at the University of Texas at Austin underlies much of the progress in the RSV field, said the news was welcome. “I think this is a big step in protecting babies from RSV and improving overall lung health,” Graham said. “All in all, it’s an exciting time for RSV. It’s also a problematic time because you see how the patterns of Covid infection have changed, and we have an earlier, longer season this year than we’ve had in a few years – and it’s causing a lot of hospitalization and misery for people.” Two promising tools to prevent RSV in infants could soon be available if regulators agree they are safe and effective. In addition to Pfizer’s parent vaccine, AstraZeneca and Sanofi showed that a single dose of a monoclonal antibody could protect infants against RSV for five months. This drug, nirsevimab, was recently recommended for approval in Europe. Two vaccines for older adults have also shown success, from Pfizer and GSK. Many pediatricians have been waiting decades for tools to combat RSV. Early efforts to create a vaccine failed disastrously, causing babies to develop an enhanced disease if infected and casting a shadow over the field. If both a preventive monoclonal antibody therapy and a vaccine soon become available, it will give doctors options — and lead to debates about how to use the different tools. “I’m so excited about where the stadium is right now. I think there are many, many people out there in the world who share my excitement,” said Ruth Karron, a pediatrician and professor of international health at the Johns Hopkins Bloomberg School of Public Health, who is working on a different vaccine that could be administered directly. in young children, for their protection after the first six months. “The difference this year is that the general public for the first time is probably looking forward to an RSV vaccine because they’re seeing firsthand how big of a problem RSV can be.”
