The availability of a new RSV immunization for infants was hailed as a major development for this winter season, especially after 2022’s so-called “tripledemic” of simultaneous flu, COVID-19 and RSV surges. But families across the country have struggled to access the new drug, a monoclonal antibody that provides babies with temporary protection against the virus. Patient and physician demand for the product has far outpaced what manufacturer Sanofi had planned to provide for this year’s RSV season, which typically lasts from about November through March in the United States.

Sanofi has made more immunizations available, releasing another 77,000 doses of the drug this past November, and putting out 230,000 additional ones this week. Those new doses, combined with the initial 1.1 million the company planned to allocate, would be enough to immunize about 40 percent of babies eligible for the drug, according to the company’s estimates. White House officials met with representatives from the drug manufacturer last week to discuss ways to meet patient demand this year as well as next RSV season.

Data from the Centers for Disease Control and Prevention suggests tens of thousands of children younger than age 5 are hospitalized each year because of the virus. Hundreds die. Prior to this year, there was no immunization available for young children, and the new shot can significantly cut the risk of major illness.

But even now, more than halfway through the year’s RSV season, the process of finding the new Beyfortus has remained opaque for the parents tasked with caring for newborns vulnerable to RSV. A vast body of research suggests mothers are more likely to be the ones responsible for making sure their children get immunized.

“It’s always going to be the moms — and sometimes the dads,” said Dr. Kerry Fierstein, a pediatrician from Plainsview, New York. “With RSV, it’s something parents have seen kids suffer. So it makes sense it’s something they would want.”

The majority of pediatricians’ offices ran out of the drug in December, said Dr. Jesse Hackell, who chairs the American Academy of Pediatrics’ Committee on Practice and Ambulatory Medicine. While he is hopeful some will receive more with the new supply available, Hackell — like many other physicians — expressed doubt it would be enough to meet the tremendous patient demand.

Allocating the drug is complicated: It is distributed in both 50-milligram and 100-milligram doses, with the smaller ones earmarked for infants weighing less than 11 pounds. But doctors don’t know in advance how many babies they will see who weigh less than 11 pounds, versus how many would require the larger dose, meaning it’s difficult to predict how many of each shot they should order.

Read the full article about RSV vaccines by Shefali Luthra at The 19th.