After 60 years of research, pharmaceutical companies are on the verge of producing a very first vaccine against respiratory syncytial virus (RSV). Less known — and less dangerous — than the viruses that cause COVID-19 or the flu, RSV nevertheless contributes to clogging hospitals in Quebec.
Similar to the flu, deadly to the young and old among us, RSV is the third triumvir of the “triple epidemic” raging in Quebec. Some 3.4 million hospitalizations and 100,000 deaths are attributable to RSV each year worldwide, according to the National Collaborating Center for Infectious Diseases.
“RSV probably has a quarter of the burden of influenza,” says Dr.r Jesse Papenburg, specialist in pediatric infectiology, medical microbiologist and co-director of the Center for Vaccine Studies at the MUHC. About one in ten RSV patients admitted to hospital will die from it, roughly speaking. “It shows that there is a fairly significant burden, even if the number of cases is less than influenza. »
Almost all children contract RSV before the age of 3 years. This virus is even the leading cause of hospitalization for children under one year old. Only Pfizer is currently working on a vaccine for this young clientele. The rest of the pharmaceuticals are focusing more on a vaccine for the elderly, who are also very vulnerable to this virus.
GlaxoSmithKline (GSK) has the lead in the race for the first RSV vaccine. The company submitted its vaccine candidate last November to Health Canada authorities for approval. Pfizer is following closely. The newest to enter the final sprint, Moderna, announced last week that it had completed its clinical trials with prevention of serious infections exceeding 80% of cases for those over 60.
Moderna’s statements do not detail the degree of safety associated with its studies. Revalidating its statistics independently will prove essential, recalls the Dr Papenburg. But, we can already conclude that these vaccines work “a bit like the vaccine against COVID-19. They are very imperfect in preventing infection, but prevent serious infections,” he says.
Moderna is the only company in the race to bet on messenger RNA technology. The other competitors, such as Pfizer, Sanofi, GSK, Bavarian Nordic, Janssen, Novavax or Regeneron, rely on other more traditional types of vaccines.
The market for these vaccines alone would be worth $10 billion a year by the end of the decade, according to financial analysts at SVB Leerink.
No vaccine currently exists to prevent RSV-associated disease. It must be said that research was largely hampered by a scandal during the 1960s. Scientists in the past had injected their substance into the arms of young children and, rather than helping them, it had aggravated their symptoms. Two guinea pigs had died as a result of this error.
The studies regained vigor about fifteen years ago, when we began to understand the complexity of the virus. “We did not realize before that RSV could cause cardiac complications, respiratory complications”, recalls the Dr Papenburg.
Even if these new vaccines have not yet been approved, or even submitted to the Canadian regulator, they are already under the radar of the Committee on Immunization of Quebec. The council of experts is beginning to think about the introduction of this newcomer in the vaccination record of Quebecers.
Towards a triple vaccination?
This year, the respiratory syncytial virus was particularly virulent. This pressure of respiratory viruses on the health system has led the government to offer the flu vaccine free of charge to the entire population.
A deployment of these vaccines in anticipation of the flu season in the fall of 2023, however, seems unlikely given the lack of time to supply vaccination clinics. About 40% of Quebecers, year after year, already receive an inoculation against the seasonal flu.
Although difficult to predict with certainty, the Dr Papenburg estimates that a triple vaccination (RSV, COVID-19, flu) at the start of the cold season could eventually become a reality in Quebec since people at risk of developing a serious illness in the case of RSV are also at risk for COVID. -19 and influenza. “It overlaps a lot. It is really the same populations that we are targeting. »
According to the specialist in infectiology, the ideal would be to have a vaccine which combines the three viruses at the same time. “Moderna is working on that,” he says.
Still, COVID-19 would have to behave like other respiratory viruses by following the seasons, which has not yet been demonstrated.