RSV fills hospitals with wheezing babies each fall and winter, and the virus struck earlier than usual and especially hard in the
If the vaccine pans out, “many infants and their parents will breathe easier in the coming years,” said Dr.
The idea: Give women a single injection late in pregnancy, between 24 weeks and 36 weeks, so they develop RSV-fighting antibodies that pass through the placenta — just like they pass protection against other bugs to their babies.
In
“If you’re in any sense risking premature births with this vaccine, I think there will be a big price to pay,” said Dr.
If the FDA ultimately approves the maternal shot, it would mark a second milestone in the decades-long quest to prevent the respiratory syncytial virus. Earlier this month the FDA approved the world’s first RSV vaccine, rival GSK’s shot for older adults, who also are at high risk. There isn't a vaccine yet for children, but
Here are some things to know:
RSV IS A COMMON THREAT
For most healthy people, RSV is a cold-like nuisance. But it can be life-threatening for the very young –- infecting deep in the lungs to cause pneumonia or impeding babies’ breathing by inflaming their tiny airways. In the
“All young infants are at risk of severe disease with RSV,” but postponing infection even by a few months lessens that risk, said CDC’s Dr.
VACCINE’S POTENTIAL IMPACT
Pfizer’s vaccine isn’t intended to prevent RSV infection but to avoid the worst outcomes. In late-stage testing, six infants born to vaccinated mothers had a severe RSV illness in their first three months of life compared to 33 infants whose mothers received a dummy shot. In addition, the vaccine cut in half the chances of needing any medical attention for an RSV infection by age 6 months.
The company predicts the
SAFETY DATA
Vaccine reactions included typically mild injection-site pain and fatigue. As for the prematurity question, vaccinated mothers had slightly more preterm infants –- 5.7% versus 4.7%. The vast majority were born just a few weeks early. That’s better than the nation’s preterm birth rate -- overall in the
Competitor GSK halted its own trials of a maternal RSV vaccine because of prematurity concerns, spurring questions about
“Do you hold hostage the potential benefits of the vaccine” without clear evidence of a problem, Dr.
“There is certainty that the vaccine works and will keep infants out of the hospital in
A total of 17 infants died during the study, five born to vaccinated mothers and 12 to those given a dummy shot. Researchers deemed none of the deaths related to the vaccine but FDA said it “is unable to exclude the possibility” that one infant’s death, stemming from extreme prematurity, might be related.
Vaccines always get close safety scrutiny but regulators are especially mindful of a major setback in the 1960s when an experimental RSV shot worsened infections in children. Eventually scientists figured out the problem and the RSV vaccines in the pipeline today are made with safer, modern methods -- yet still were tested first in older adults.
ANOTHER OPEN QUESTION
WHAT HAPPENS NEXT?
FDA’s advisers already have recommended approving Pfizer’s vaccine for older adults, and the agency is expected to make a decision by month’s end. Whether to use the same shot in pregnant women will be a separate FDA decision, expected in August.
Meanwhile, rival GSK is gearing up for fall immunizations with its RSV vaccine for seniors. First, the
Vaccines aren’t the only advance in the pipeline. High-risk infants can get monthly doses of a protective drug during RSV season, although
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