In the foreseeable future, babies, pregnant women and the elderly can be vaccinated against a serious infection with the RS virus. At least this is evident from three studies published last week.
The development of vaccines against this virus has its origins in the elucidation of the structure of the RSV fusion (F) glycoprotein, the Achilles’ heel of the virus. It occurs in two forms. Antibodies targeting the prefusion form neutralize RSV approximately 10 times more efficiently than antibodies targeting the postfusion form.
The RSVpreF vaccine is of the first type and its effectiveness has been studied in older adults in the RSV Vaccine Efficacy Study in Older Adults Immunized against RSV Disease (RENOIR) study and in infants born to women who received the vaccine during pregnancy in the framework of the Maternal Immunization Study for Safety and Efficacy (MATISSE) trial. Both are phase 3 trials that are ongoing and interim analyzes have been presented in the New England Journal of Medicine.
EEWalsh et al report the results of the RENOIR study: of the more than 34,000 participants, half received the vaccine and half received a placebo. RSV-associated lower respiratory tract disease occurred in 11 participants in the vaccine group versus 33 participants in the placebo group. RSV-associated acute respiratory disease was seen in 22 participants in the vaccine group and 58 participants in the placebo group.
B. Kampmann et al publish the MATISSE trial, conducted among 7400 mothers and their newborn child. Within 90 days of birth, an RS virus infection was found in six children of the group with mothers who had been vaccinated and in 33 children of mothers who received a placebo. After 180 days, those numbers were 19 and 62, respectively.
There is also a new vaccine that is specifically intended for newborns as a long-acting antibody against RSV. Deidre Wilkins et al. publish about this in The Lancet Infectious Diseases. It concerns nirsevimab that also binds to the prefusion form of the glycoprotein. The researchers saw that the protein in question does not mutate, which means that the chance that the virus will become resistant – and the effect of this vaccine will therefore decrease – is extremely small.
Infection with the RS virus was first reported 66 years ago in young children with lower respiratory tract disease who were hospitalized in Baltimore. It has since been found to be the leading cause of pneumonia in young children worldwide. In children under 5 years of age, the virus is associated with approximately 33 million cases of lower respiratory tract disease, 3.6 million hospitalizations and more than 100,000 deaths per year. Infants less than 6 months of age are at the greatest risk of RSV-associated illness and death, and more than 95% of RSV-associated deaths occur in low- and middle-income countries. This makes infections with the RS virus the second leading cause of death in infants, after malaria.
The new vaccines are 80 percent effective. Pediatrician-infectiologist Prof. dr. Dr. Louis Bont (UMC Utrecht), involved in all three studies, estimates that vaccination can prevent between 1,000 and 1,500 admissions per year. An advice on that vaccine is only useful if it has been done, she explains. ask for advice on adding one or both vaccines to the National Immunization Programme. The vaccine that must be administered to pregnant women has not yet been approved in Europe.