RSV Vaccine Shortage Affects Babies and Toddlers

Sunday - November 5 2023, 05:43 UTC - 1 year ago

RSV (Respiratory Syncytial Virus) is a serious virus affecting infants and toddlers and, despite the new shot, Nirsevimab, being available, it is currently in short supply due to high demand. Sanofi is working with AstraZeneca to restock supplies, while the monoclonal antibody, Palivizumab, is reserved for babies born prematurely or with chronic lung/heart disease.

This year we were supposed to have more tools than ever before to protect kids from RSV (short for respiratory syncytial virus), including a new shot called nirsevimab that’s given preventively to babies and vulnerable toddlers to protect them from the worst effects of the virus. But now—just as rates of sickness are rising—this medicine is in short supply. The CDC issued an alert last week advising pediatricians to ration doses, reserving them for babies younger than six months and those with underlying conditions that place them at highest risk for severe RSV .

Demand was higher than expected, says Evan Berland, a spokesperson for Sanofi, which partnered with AstraZeneca to develop and market the drug. He adds that demand topped estimates "based on the most aggressive analogues of historical pediatric immunization launches." "This was an unusual situation," says Michael Ganio, senior director of pharmacy practice and quality at the American Society of Health-System Pharmacists .

Nirsevimab is the first drug of its kind, so there’s no good baseline for comparison. What’s more, babies whose mothers have been vaccinated within 14 days of giving birth don’t need the medicine, which introduces additional uncertainty to the calculations. Last year, RSV cases surged in the fall, overwhelming hospitals and prompting some states to call a state of emergency. So pediatricians were especially keen to have nirsevimab as an option this fall .

In August, the CDC recommended the treatment for all infants younger than eight months old who are heading into their first RSV season. The agency also recommended the shot for older babies and toddlers up to 19 months who have a higher risk of serious illness due to RSV. Nirsevimab is a shot, but it’s not a vaccine. It’s a lab-made antibody that provides protection for about five months, the length of the RSV season .

The antibody binds to the virus and blocks it from infecting cells, curbing severe disease. In clinical trials, the drug prevented 80% of RSV-related hospitalizations and 90% of ICU admissions compared with a placebo. But in mid-October, when the family’s pediatrician tried to order the medication, she couldn’t find any. "She told my husband, ‘They just don’t have it. I can’t order it. It’s nowhere to be found,’" Ithen says .

Sanofi declined to disclose the number of doses already delivered, the size of the shortfall, or the timeline for restocking the drug. For now, the company isn’t accepting new orders of the 100-milligram dose, which is meant for babies weighing more than 11 pounds. The 50-milligram dose is available, Berland says, but is reserved for the smallest babies. Sanofi says it’s working with AstraZeneca, which manufactures the drug, to boost supplies .

But producing monoclonal antibodies is a complex process that requires bioreactors full of living cells, and making more doses will take time. "Clinicians and caregivers should expect limited supply during this winter," Ganio says. Parents can also try to get a monoclonal antibody called palivizumab, which has been used for more than two decades. But it’s only available for babies who were born prematurelty or who have chronic lung or heart disease .