A single injection of the monoclonal antibody nirsevimab could protect healthy infants against lower respiratory tract infections caused by respiratory syncytial virus (RSV) for up to a year, a study has found.
If approved, it would be the first potential immunization of all infants against RSV, which causes the death of around 30 babies a year in the UK.
the phase III study, published in the New England Journal of Medicine on March 2, 2022, randomized 1,490 healthy infants in their first year of life to receive either a single intramuscular injection of nirsevimab or a placebo.
The injections were given before the start of the RSV season, which usually occurs between October and March each year, and followed for 150 days.
At 150 days post-injection, RSV-associated lower respiratory tract infection requiring healthcare professional attention occurred in 12 infants (1.2%) in the nirsevimab group and 25 infants (5. 0%) in the placebo group.
The researchers calculated this result to correspond to an efficacy of 74.5% (95% confidence interval [CI]49.6 to 87.1; p
Overall, six infants in the nirsevimab group were hospitalized with RSV (0.6%), compared with eight infants (1.6%) in the placebo group.
In the UK, only infants at risk – such as those born at less than 35 weeks gestational age or those aged less than 2 years who have received treatment for haemodynamically significant bronchopulmonary dysplasia or congenital heart disease – are offered a five-dose treatment regimen of the monoclonal antibody palivizumab.
However, the authors note that there is a “serious unmet medical need” for protection against RSV in healthy term infants..
William Muller, Scientific Director of Clinical and Community Trials at the Stanley Manne Children’s Research Institute at the Ann and Robert H Lurie Children’s Hospital in Chicago and principal investigator of the study, said: “These exciting data show that nirsevimab has the potential to offer protection against RSV for all infants, which would be a paradigm shift in the approach to this disease.
“We know RSV has seen a resurgence with the easing of COVID-19 public health measures. This shows us that a broad vaccination approach is needed to help alleviate the substantial global burden that RSV places on infants, their families and health services.
Dan Hawcutt, consultant in pediatric clinical pharmacology, said RSV was a “significant” cause of hospital admissions for infants, especially those aged six months and younger.
“Before COVID-19, and probably in the future, it was seasonal in nature, with large peaks in the winter months resulting in admissions to wards and intensive care units, across Britain and the world,” he said.
“Risk is higher in infants with additional risk factors, such as prematurity, neuromuscular disease, or other chronic disease.”
Hawcutt said the risks and benefits of nirsevimab should be “carefully considered” by national bodies, such as the Joint Committee on Vaccinations and Immunizations (JCVI), to determine whether the treatment would provide a “net benefit” if he was deployed.
“As the treatment is administered by intramuscular injection, like a vaccination, the discomfort, potential side effects and cost of deploying such a program will need to be weighed against the benefits described,” he continued.
“However, this still represents a significant development on the road to RSV prevention, and coupled with the clinical trials of RSV treatments underway at the moment, it is an exciting time in the treatment of this serious disease in babies. .”
Steve Tomlin, chief pharmacist at Great Ormond Street Hospital, said his trust “has been using palivizumab in vulnerable infants for many years now”.
“However, it is only used in the most vulnerable and not in all infants for whom it is licensed.”
As a single dose offering long-lasting protection against RSV, Tomlin emphasized that nirsevimab represents “a big step forward for health services, and an even bigger step forward for developing countries.”
In August 2021, the JCVI recommended that nirsevimab be considered for the prevention of RSV in certain groups of young children.
Minutes of a meeting of the Joint Committee on Vaccination and Immunization (JCVI), held on June 22, 2021, noted that the long-acting monoclonal product “looked promising” and required only a single dose to the entire RSV season.
JCVI members agreed that “every effort” should be made to explore the potential use of the new monoclonal antibody for “the coming winter”.