Respiratory syncytial virus (RSV) is a dangerous early childhood viral infection, but results of a vaccine promise to change things radically.

A new study published in the New England Journal of Medicine, the world’s most prestigious medical journal, on 5 April that examined the effect of an RSV vaccine on pregnant women found that it reduced the risk of severe lower respiratory tract infections in newborns by 82%.

RSV is the most common cause of acute lower respiratory infection — or pneumonia — in infants. Globally, it was responsible for just over 100,000 deaths (with a lower bound of 84,000 deaths and an upper bound of 126,000 deaths) of children under five in 2019. Of these deaths, 45% were infants (younger than six months), and nearly all deaths occurred in lower-income countries (half in Africa alone). In an article in Spotlight in June 2022, Professor Cheryl Cohen, head of the Centre for Respiratory Diseases and Meningitis at the National Institute for Communicable Diseases (NICD), said that, pre-Covid, RSV led to 44,615 hospitalisations and 490 deaths in children under five each year in South Africa.

South Africa is currently experiencing an RSV epidemic, with 301 cases detected this year, according to the NICD surveillance programme.

RSV causes cold-like symptoms, but can lead to severe symptoms like pneumonia. At present, there is no licensed RSV vaccine, though the virus was first identified in the 1960s.

The study was a phase three, double-blind trial (which compares a new treatment to standard care, and leads the way to regulatory approval and production) conducted in 18 countries, led by Beate Kampmann, Professor of Paediatric Infection and Immunity at the London School of Hygiene and Tropical Medicine, Shabir Madhi, Dean of the Faculty of Health Sciences and Professor of Vaccinology at the University of the Witwatersrand, and Iona Munjal, Director of Clinical Research & Development at Pfizer. It builds on earlier work by Madhi and others.

Women who were between 24 and 36 weeks pregnant were given an injection of a protein–based vaccine (RSVpreF) and a placebo. Pregnant women can passively transfer their immunity to viruses and diseases to their foetuses in utero.

They were then monitored to see if they suffered a severe RSV-associated lower respiratory tract illness that required medical attention, and if their newborns required medical attention for RSV-associated lower respiratory tract illness up to six months after birth.

A total of 7,358 women participated across the two trial groups, and 7,128 babies were monitored, and no safety concerns were identified over the course of the trial.

In November last year, Pfizer announced that it planned to submit a licence application to the US Food and Drug Administration after trials showed that the vaccine was highly effective at reducing severe RSV cases in the first 90 days of an infant’s life.

In a Twitter thread announcing the results, Madhi said that the next challenge would be to ensure that the vaccine is licensed across lower-income countries, where most infant RSV deaths occur. Madhi said that there is a “moral responsibility on pharma to licence [the RSV] vaccine in LMIC [lower and middle-income countries] at [an] affordable price.” Governments in poorer countries, “need to act to protect children in their counties by funding and deploying the vaccine timeously,” he said.

Madhi also informed GroundUp that coincidentally in the same issue of the New England Journal of Medicine, a medicine called nirsevimab was found to protect infants against RSV-associated hospitalisation and severe lower respiratory tract infections. Madhi and his team at Wits also participated in this trial.

This medicine is “administered as a single dose at the onset of RSV season,” Madhi explained. “The two approaches [the vaccine and nirsevimab] will be complementary.” DM

First published by GroundUp.