Pfizer's RSV vaccine for pregnant women protects newborns against severe illness

Pfizer has announced that an experimental RSV vaccine for pregnant women has the potential to protect newborn babies from severe illness for about six months after birth.

The company says that in phase III of a randomised, double-blind, placebo-controlled study, considered the gold standard of epidemiologic studies, the vaccine was found to be about 82% effective at preventing severe cases of respiratory syncytial virus, or RSV, in infants whose mothers were immunised. This level of protection was observed from birth through three months of age. At six months of age, there was a reduction in protection, but the Pfizer vaccine was still 69% effective against the illness.

In order to assess the safety and efficacy of the vaccine, pregnant women who participated in the study were observed through vaccination and for six months after giving birth. Infants were followed for at least one year, with over half followed for two years, reports Yahoo News.

"As someone who spent part of their ID training focused on RSV research, this is wonderful news," said Dr Michael Chang, pediatric infectious diseases specialist with UTHealth Houston and Children's Memorial Hermann Hospital.

RSV is a common respiratory virus that causes mild, cold-like symptoms. Even though 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, younger kids and older adults. Severe infections can lead to bronchiolitis, an inflammation in the lung, as well as pneumonia.

According to the Centres for Disease Control and Prevention, RSV season occurs in most regions of the US during the fall, winter and spring. However, this year, it started in the late summer — much earlier than expected. For weeks, many hospitals across the nation have been overwhelmed with a high number of sick children who need hospitalisation.

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