A Virus-Induced Vaccination Strategy to Prevent and Defend the Spread of RSV in Pregnant Infants
Efforts to develop an RSV vaccine were set back substantially after a particularly notable failure in the 1960s. Researchers were able to produce a vaccine that had been inactivated to stop the viruses from replicating. In a clinical trial, two infants died when they were tested on the shot. The infants began to take the vaccine well, according to a structural biologist at the University of Texas at Austin. But during the next cold and flu season, 80% of the children who had received a shot and then subsequently caught RSV became so ill they were hospitalized1. Only 5% of children who received placebo and then caught the disease ended up in the hospital.
The optimism about RSV prevention in children isn’t just about vaccinating pregnant people. There is an alternative to prophylactically injecting newborn babies with an anti-RSV vaccine that was approved for widespread use in November of last year. As well as providing choice for parents, Bont says that the antibodies may be important for premature babies who did not receive sufficient antibodies from their vaccinated parents.
Rather than try to make a vaccine from inactivated viruses, researchers attempted to make a vaccine that used a surface component of the Viruses and triggered a protective immune response A major breakthrough came when scientists, including McLellan, characterized the different conformations of protein F, a molecule found on the surface of RSV. The host cell’s membranes is brought together by the Protein F, so that the Viruses can enter the cell.
Protein F exists in two forms: a postfusion form, which is highly stable, and a prefusion form, which is not. During an epidemic of the virus, the prefusion form of the protein takes over and transitions to the second form once the epidemic is over.
The Impact of Vaccines on the Health-Care System: A Case Study of the Pfizer-GSK-Vaccine for Pregnant People in South Africa
The vaccine candidate from Pfizer was found to be effective in two trials earlier this year. The firm gave vaccine to pregnant people to increase their total antibody numbers, the hope being that those antibodies will be transferred to their infants.
In young and elderly people,RSV causes mild cold-like symptoms but can be dangerous. Cases have soared in recent months, putting stress on health-care systems. Babies that are between one month and one year old are the second-highest cause of death behind Malaria. For adults, the data are sparser: a study1 in 2022 estimated that around 6,500 people in the United States die of RSV annually, with the highest rates in people over 65.
Moderna’s mRNA-based vaccine stimulates the production of a stabilized version of this protein, whereas the Pfizer and GSK vaccines inject synthetic versions of it directly. In trials, their efficacies have been remarkably similar, although Bont expects differences to emerge in their initial protection they offer and the durability of immunity after they are rolled out on a larger scale.
It is also not clear how strongly countries will recommend the vaccine for over-60s. Cheryl Cohen, an epidemiologist at the University of Witwatersrand in Johannesburg, South Africa, said that the impact of an RSV vaccine for older people is very low in South Africa. Older people make up a small proportion of its total population and flu vaccines have not achieved good uptake in this group.
Cohen says that the vaccine for infants is one of the top new products they are looking for. The benefits she lists — preventing a large number of hospitalizations and deaths, relieving stress on hospitals and the fact that pregnant people are in frequent contact with health-care systems, meaning vaccines can be integrated into routine care — apply across low-, middle- and high-income countries.