Laval University Vaccine: Promising Protection Against RSV & Other Viruses in Toddlers

A novel vaccine under development at Laval University in Quebec holds the potential to protect young children from three respiratory illnesses, including respiratory syncytial virus (RSV), a leading cause of severe illness in infants and toddlers.

This prospective vaccine represents a significant step forward, as currently, no vaccines are approved for these specific respiratory viruses in children under five years of age. According to Dr. Guy Boivin, a professor of medicine at Laval University and a researcher at the CHU de Québec – Laval University Research Center, vaccines for RSV are available for older adults, but a pediatric formulation has remained elusive until now.

The need for a pediatric RSV vaccine is particularly acute, as current preventative measures offer only temporary protection. Dr. Boivin explained that for the past couple of years, infants born during the winter and spring months have been receiving RSV antibodies, but this protection wanes after approximately six months. “So this is where we need to vaccinate and if possible, vaccinate for a long period, because we don’t want to have to vaccinate every year, for example, as we do for influenza,” he stated.

The research team initially developed a “bivalent” vaccine targeting human metapneumovirus and RSV, both common causes of bronchiolitis and pneumonia in young children. Building on this success, they have now engineered a “trivalent” vaccine, incorporating proteins from a third virus to broaden the scope of protection.

Preclinical studies in mice have yielded promising results. The experimental vaccine triggered a robust antibody response and effectively blocked viral replication in the lungs. Dr. Boivin reported that the vaccine “covers 95% of the causes of bronchiolitis […] and more than 80% of the causes of mortality for pneumonia in young children.” These findings were independently corroborated by a study conducted by the U.S. National Institutes of Health using cotton rats, further bolstering confidence in the vaccine’s potential efficacy.

The vaccine’s design incorporates a modified strain of human metapneumovirus, with the gene responsible for significant inflammation in young children removed – creating what researchers term an “attenuated virus.” To this platform, the team added the surface protein of RSV and proteins from a third virus, creating a broad-spectrum approach to respiratory protection.

A key innovation of this vaccine is its nasal administration. This method not only avoids the discomfort of needles but also aims to establish immunity directly within the nasal passages, providing a first line of defense against viral entry. “It creates a wall,” Dr. Boivin illustrated. “It is a barrier to the entry of the virus because it enters through the nose. So, after vaccination, the viruses will not be able to penetrate adequately because of this barrier which will have been built, so to speak, by vaccination.”

Developing new vaccines against mucosal respiratory viruses remains a complex undertaking, despite significant research efforts. The study authors emphasize that their vaccine candidate “could provide a promising new option to protect children, young adults at risk and older adults who need specific strategies appropriate in terms of vaccine response, timing and treatment regimen.”

While the initial focus is on protecting young children, Dr. Boivin’s team is exploring the potential applicability of the vaccine to other populations. However, he cautioned that the vaccine would not be suitable for individuals with compromised immune systems or pregnant women, as even an attenuated virus could pose a risk in these cases.

The research findings have been published in the journal npj vaccines, marking a significant milestone in the quest for effective respiratory virus prevention in young children. Further research and clinical trials will be necessary to confirm the vaccine’s safety and efficacy in humans, but the initial results offer a hopeful outlook for the future of pediatric respiratory health.

The development of this vaccine builds on a broader effort to address the challenges of RSV prevention. Recent advancements include monoclonal antibody injections for infants and a maternal vaccine that provides protection to newborns through the placenta. However, a long-lasting vaccine for toddlers and preschoolers remains a crucial goal, potentially offering sustained immunity beyond the first few months of life. As James Campbell, an infectious disease pediatrician at the University of Maryland, has noted, this represents the possibility of “true vaccines” for children after their first birthday.