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Seasonal surge in RSV has begun in Massachusetts, and a drug to treat it is limited

Supplies of monoclonal antibodies will remain tight through this season

Some doctors and parents are frustrated that a new drug designed to protect babies from a common and serious infection is in short supply.JAMIE KELTER DAVIS/NYT

The seasonal surge in the respiratory illness RSV has begun in Massachusetts, as prospects dim for adequate supplies of a drug that experts had touted as a lifesaver for babies.

“The surge is on its way,” said Dr. Laura J Cardello, director of inpatient pediatrics at South Shore Hospital. “We’re not at the peak, but we’re definitely on the upswing.” In the last two weeks, RSV was diagnosed in half of children seen at the hospital for respiratory illness, and it is expected to soon become the dominant virus, Cardello said.

In August, the Centers for Disease Control and Prevention recommended nirsevimab, a monoclonal antibody, for all infants under 8 months entering their first RSV season, calling it “a powerful new tool” to protect babies from a leading cause of hospitalization.


But no sooner had doctors started ordering the drug than the manufacturer, Sanofi, announced it would not be able to meet the demand.

Last month’s hopes for a quick resolution of the supply problems with nirsevimab have been dashed. “It was optimistic thinking,” said Dr. Rick Malley, senior physician in infectious disease at Boston Children’s Hospital. The hospital, he said, is already seeing a “fair number” of RSV cases.

Nearly 22,000 doses have been distributed to hospitals and medical practices in Massachusetts, but there are roughly 80,000 children who would have been eligible this season, according the state Department of Public Health.

“A number of families in my care were waiting for their baby’s turn to get protected against RSV,” Dr. Mary Beth Miotto, president of the Massachusetts chapter of the American Academy of Pediatrics, said in an email. “The parent of a toddler who was hospitalized in fall 2022 was almost in tears when I told her I wasn’t able to administer the RSV monoclonal antibody to her young infant. I’m personally devastated that a corporation can promise a supply, make the rounds to gin up demand among pediatric leaders who’ve seen so many children hospitalized for RSV and then throw up their hands a month into the season.”


Sanofi said in a statement that it had put in place “an aggressive supply plan built to outperform past pediatric immunization launches,” but that demand had been greater than anticipated. The company said it would no longer take orders for 100-mg doses, which are for children who weigh more than 11 pounds, but it is “carefully managing distribution of the 50 mg doses in the private market to fulfill existing orders and provide equitable access to remaining doses.”

RSV, or respiratory syncytial virus, causes a mild cold in most who become infected — but it can be dangerous for infants whose tiny airways are vulnerable. Even babies with no underlying health problems can get sick enough to need a doctor’s visit, a trip to the emergency room, hospitalization, and sometimes intensive care. Each year, an estimated 58,000 to 80,000 children under age 5, most of them infants, are hospitalized with RSV infections, and an estimated 100 to 300 children younger than 5 die.

The shortage of monoclonal antibodies does not affect the new RSV vaccines for seniors, which are made by different manufacturers and are available to those 60 and older.

One bright spot: Throughout the state, hospitals where women give birth have received supplies of the 50-mg shots and started immunizing newborns, protecting those who are at greatest risk. So far hospitals have received 2,760 doses and 1,853 have been administered to newborns. (About 5,750 babies are born each month in Massachusetts.)


South Shore Hospital, for example, started immunizing newborns in mid-October, took a break when supplies dried up, and resumed injecting babies on Nov. 2. The shot has been offered to the parents of every newborn at her hospital since then, Cardello said.

But when Carly Gildea gave birth in mid-September, the monoclonal antibodies were not yet available and her baby didn’t get immunized as a newborn. And her pediatrician hasn’t been able to obtain the medication for his practice.

Her son was born 3½ weeks early, weighing just under 5 pounds, and now he’s only 7½ pounds. The shot, she said, would have lessened the stress of going out. She knows two families whose young children caught RSV.

“It’s just scary. You want to be able to go and see family over the holidays,” said Gildea, who is on maternity leave as a first-grade teacher and who lives in Bridgewater. “With a tiny baby you have to be very careful.”

So her family is planning a very small Thanksgiving, and Gildea will keep her son in the baby wrap, close to her.

Health officials said the state — which is ordering and distributing the medication through the federal Vaccines for Children Program — expects an additional 4,000 doses of the 50-mg formulation for small babies in the coming weeks, but no more. Those doses will go exclusively to the birthing hospitals. “We are trying to ensure all newborns are able to receive a dose,” a spokesperson said.


Doctors in private practice, however, have been told that there will be no more 100-mg doses this season. Health officials have asked them to reserve any remaining supply for children younger than 6 months and those with high-risk conditions.

All told, 9,555 Massachusetts children (including the newborns) have received doses of nirsevimab as of Tuesday.

More than 18,000 doses have been distributed to providers outside of hospitals, but it’s been distributed unevenly, with some doctors getting doses and others coming up dry.

“We have not been able to get any,” said Dr. Howard H. Kay, president of Brockton Pediatrics and Gildea’s doctor. “We’ve been told we won’t get any until next year.”

“Some pediatric practices were able to administer a limited number of doses in early October,” said Miotto, who is a staff pediatrician at the Mattapan Community Health Center, “and some, like my community health center practice, never received any doses and will likely start up in October 2024.”

When the Food and Drug Administration in July approved nirsevimab, also known by the brand name Beyfortus, doctors were hopeful for a drop-off in hospitalizations and deaths from RSV. The drug is a monoclonal antibody, which provides synthetic antibodies to fight the infection. (Vaccines, in contrast, trigger the immune system to produce its own antibodies.) The CDC recommended the shots for all infants under 8 months and high-risk children ages 8 months to 19 months.


So far this season, the percentage of emergency room visits and hospitalizations attributed to RSV is about a quarter of what it was at this time last year, when the RSV epidemic peaked early and was especially severe.

“It’s too soon to say whether it will be an average year, a good year, or a bad year,” said Malley of Boston Children’s.

Parents do have another way to protect their children: Pregnant women can receive a vaccine, which is in ample supply, within two weeks of delivery and that will protect their babies from RSV through the season. Those vaccinations, along with newborns getting the shots of nirsevimab, offer some hope that severe illness will be at least somewhat limited this year, said Dr. Vandana Madhavan, clinical director of pediatric infectious disease at the Mass. General Hospital for Children.

“It will be interesting to see, given this perfect storm of these tools arriving just around the onset of RSV season, will we see a big impact this season?” Madhavan said. “These tools are here to stay. We do hope we’ll see blunting in severe complications.”

Meanwhile, a Canadian study published Tuesday pointed to the impact of measures that don’t involve medications. In the largest study of its kind, published in JAMA Network Open, researchers tallied the hospitalizations for respiratory illness among children across Canada from April 1, 2020, through Feb. 28, 2022, and compared those with hospitalizations during the three previous years. Even amid a pandemic, children were dramatically less likely to be hospitalized, need intensive care, or die from respiratory illness, because protections against COVID prevented the circulation of other viruses like RSV.

“We need to take the lessons learned during COVID and reflect on how we approach interventions and policies that would impact public health,” said Christina Belza, lead author of the study and a nurse practitioner at the Hospital for Sick Children in Toronto.

But because adherence to different types of protections varied from community to community, the study could not point to which were most effective, she added.

Still, South Shore Hospital’s Cardello, when asked what parents should do if they can’t get the monoclonal antibodies, pointed to the pandemic’s lessons.

“All of the things we learned protecting ourselves from the COVID pandemic would apply here as well,” she said. “Good handwashing, staying away from crowds, keeping people sick with any cold symptoms away from your infant.”

Felice J. Freyer can be reached at Follow her @felicejfreyer.