Grant: Project Grant

Respiratory syncytial virus (RSV) is one of the main causes of respiratory illness in infants. Until 2023, preventive options (immunization products) to protect infants against this virus were limited. However, two immunization products to prevent RSV infection in the first months of an infant's life have been authorized in Canada and started being recommended in 2024. One option is RSVpreF, an immunization product given during pregnancy where protection against RSV would pass from the pregnant person to the unborn infant. Another option is nirsevimab given to the newborn during the first months of life. These options have been tested in pharmaceutical industry studies but there is no data on real-life use of RSVpreF and nirsevimab. Our study will use routinely collected hospital, birth registry, and public health data in Ontario to investigate the impact of RSVpreF and nirsevimab administration in preventing infant RSV infections. We want to understand if these immunization products can protect infants from having an RSV infection and what is the impact for pregnant people and newborns to receive RSVpreF and nirsevimab, respectively. We will establish a large dataset of pregnant people and newborns who received RSVpreF and/or nirsevimab in Ontario. Within this dataset, we will investigate the protection against RSV (RSVpreF in pregnancy and/or newborn receipt of nirsevimab). We are also interested in understanding the characteristics of the population receiving these products and the potential disparities associated with the uptake of RSVpreF and nirsevimab. With this approach, we will have the information necessary to address critical questions about the impact of the recently recommended immunization products in protecting infants from RSV infection. We will use our findings to help inform maternity and infant healthcare providers, health agencies, and Canadian families about the potential risks and benefits associated with the use of RSVpreF and/or nirsevimab.