By James Stent

A new vaccine can prevent many of the annual 100,000 deaths from RSV in children across the
world.

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.

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.

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.”