Maternal RSV vaccine births hope to conquer pneumonia deaths in children

Pneumonia and bronchitis are some of the leading causes of death among youngsters with about 4,000 of SA’s children succumbing to pneumonia each year, mostly caused by respiratory syncytial virus (RSV) that infects almost half-a-million children. 

But researchers are now convinced they may have found a solution to these unnecessary deaths and argue vaccinating mothers against RSV while still pregnant may save many young children who die from lower respiratory infections.  

This is after a large clinical trial that was conducted in South Africa and 17 other countries showed that doing so significantly lowered infections in newborns. The Maternal Immunisation Study for Safety and Efficacy (Matisse) Phase 3 trial, led by one of renowned SA epidemiologists Prof Shabir Madhi, tested whether Pfizer vaccine candidate RSVpreF was safe and effective. 

They found that it lowered the risks of infections in babies by 82% in the first 90 days. It’s the first time pregnant women are being vaccinated against RSV to protect their infants. 

In a separate investigation also published in the New England Journal of Medicine among adults aged 60 and older, the vaccine proved to be up to 86% effective against RSV-associated lower respiratory tract illnesses. 

Madhi said the latest findings “add to the portfolio of research on vaccination of pregnant women to protect the mother, foetus and newborn”. 

“The release of these study findings, in which South African scientists played a prominent role, comes at a time when RSV is back with a vengeance in South Africa, with paediatric wards being filled with children in whom illness can now be prevented with this new RSV vaccine.” 

Researchers at the Wits vaccines and infectious diseases analytics research unit, who led the trial, wanted to find out if administering Pfizer’s Bivalent Prefusion F Vaccine in pregnancy could reduce the burden of RSV-associated lower respiratory tract illness in newborns and infants and, if so, how well and for how long. 

In South Africa, it is estimated that between 178,000 and 443,000 children under the age of five will be infected with RSV annually. Numbers were, however, dramatically lower in 2020 and 2021 due to the Covid-19 pandemic and associated restrictions. 

RSV is the most common cause of lower respiratory infections, hospitalisation and deaths in children under five years of age, and even more so in those younger than six months. About two-thirds of children will be infected at least once by RSV in the first two years of life, a third of whom will develop lower respiratory infection. There is currently no antiviral treatment for children with RSV infection, and management of infections is symptom-based. 

Madhi said the latest findings show the vaccine candidate (RSVpreF), administered during the late second or third trimester of pregnancy, may protect infants from severe RSV illness during the first few months of life. “This would be particularly important in low- and middle-income countries, where the burden of RSV-associated lower respiratory tract illness is highest.”

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