Pfizer’s RSV vaccine for pregnant women protects newborns from serious disease

Pfizer announced Tuesday that an experimental RSV vaccine for pregnant women protects newborns from serious illness for at least six months after birth.

In a phase III randomized, double-blind, placebo-controlled study, considered the gold standard of epidemiological studies, the vaccine was found to be about 82% effective in preventing severe cases of respiratory syncytial virus, or RSV, in children that their mothers. have been immunized. This level of protection was observed from birth to 3 months of age. At the age of 6 months, there was a reduction in protection, but the Pfizer vaccine was still 69% effective against the disease, according to the company.

To evaluate the safety and effectiveness of the vaccine, pregnant women who participated in the study were observed for vaccination and for six months after giving birth. Children were followed for at least one year, with more than half followed for two years.

“As someone who spent part of his ID training focused on RSV research, this is wonderful news,” Dr. Michael Chang, a pediatric infectious disease specialist with UTHealth Houston and Children’s Memorial Hermann Hospital, said. told Yahoo News.

RSV is a common respiratory virus that causes mild, cold-like symptoms. Although most children and adults infected with RSV generally recover without significant long-term effects, Chang explained that the virus can be serious and even life-threatening for infants, children younger and older adults. Severe infections can lead to bronchiolitis, an inflammation in the lungs, and even pneumonia.

According to the Centers for Disease Control and Prevention, RSV season occurs in most regions of the United States during the fall, winter, and spring. However, this year, it started at the end of summer – much earlier than expected. For weeks, many hospitals across the nation have been overwhelmed by a large number of sick children who need hospitalization.

On Tuesday, officials in Orange County, California, declared a health emergency amid a surge in RSV cases, severely limiting availability at the region’s pediatric hospitals. Los Angeles Times reported.

“The burden of the annual RSV epidemic is enormous from an emotional and resource perspective (estimated $2.6 billion in annual costs). Any strategy that could have a significant impact on reducing this burden is greatly appreciated,” said Chang on to the vaccine. “Even ‘just’ a 50% reduction from 55,000-125,000 hospitalizations per year would be a significant relief for families and the health system.”

Although this vaccine has the potential to be a “game changer,” according to Chang, he noted that there are several factors that must be considered, including that a significant burden of disease occurs in children older than 1 year . . In addition, he said that RSV mortality is greater among babies who are premature or who have cyanotic congenital heart disease. These patients, he added, could not benefit from this type of vaccination. “The impact of maternal vaccination on these populations remains to be seen,” he said.

Chang noted that maternal vaccination has previously been used successfully for pertussis (whooping cough), and emerging data has shown that mothers who receive COVID-19 vaccines during pregnancy can also pass protective antibodies to their babies.

“Maternal antibodies against many infections are transferred trans-placentally to the developing fetus, mainly in the last 4 to 6 weeks of pregnancy,” said Chang. “If mothers receive a vaccination in the late second trimester to early third trimester and develop a robust immune response, these protective antibodies … can be transferred to the baby.”

However, he said the amount of circulating maternal antibodies in a baby typically declines significantly by 6 months, and that is likely to happen with the Pfizer maternal RSV vaccine as well. Whether children should be vaccinated later to be protected will be determined by further studies.

In addition to testing the vaccine in pregnant women, Pfizer said it intends to test it in younger age groups as well as older people, who are also at risk of severe infection. In August, the company reported promising results for a trial of their vaccine in older adults.

According to Pfizer, the company plans to submit a license application to the FDA in late 2022. If approved, the vaccine could be available in late 2023 or early 2024.

“After years of having to tell parents, ‘We’ll just have to treat the symptoms and wait’ for their child to get better from their RSV infection, I welcome the day when I may never have to think about RSV again.” said Chang.

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