GlaxoSmithKline (GSK) has kicked off a phase III study of its Respiratory Syncytial Virus (RSV) vaccine candidate for maternal immunisation.

The phase III launch follows the announcement of positive phase I/II data for the vaccine candidate – GSK3888550A – reported last month.

The data showed ‘promising’ safety and immunogenicity in the phase I/II study in non-pregnant women, inducing a high level of protecting neutralising antibodies. This included a 14-fold increase in RSV-A and RSV-B neutralising antibody titers observed as early as one week after immunisation.

The phase III GRACE study will involve up to 10,000 pregnant women aged 18-49 years, and will evaluate the efficacy of a single dose of the RSV vaccine for the prevention of medically assessed RSV-associated LRTIs in new-born infants.

The study will also evaluate the safety of the RSV vaccine candidate both in vaccinated mothers and in their infants.

Approximately 33 million cases of RSV occur in children under the age of five globally each year, with over 1.4 million hospitalisations of infants under six months of age.

RSV is also a leading cause of respiratory infections – including bronchiolitis and inflammatory pneumonia – in infants.

“RSV burden is high amongst young infants – a vaccine which protects them from birth would represent significant progress in addressing the burden of RSV, preventing infant illness and families’ distress, as well as reducing the associated burden for society,” said Emmanuel Hanon, senior vice president and head of vaccines R&D for GSK.

“Advancing our portfolio of RSV vaccine candidates based on robust available data is a major step towards GSK’s goal of reducing the RSV-associated disease burden around the world,” he added.