While Buenos Aires Health Minister Nicolás Kreplak says the current bronchiolitis outbreak is "the worst in history" and other experts are more cautious, there are drugs in the pipeline that could soon be a balm against a disease that every year stresses health systems and in some cases can be serious and even deadly.
Some of these new developments are vaccines, the first of which was recently approved in the United States, but only for those over 60. And the most important problem today occurs in children under 2 years old. Another vaccine, from the Pfizer laboratory, is in the process of being approved in that country and the objective would be pregnant women, so that babies are born protected.
But the immediate good news comes from the Annual Meeting of the European Society for Infectious Diseases in Paediatrics, where phase IIIb results from the "Harmonie" clinical trial were presented, which showed that the drug nirsevimab showed an 83 percent reduction in hospitalizations.
The previous, phase III trial, dubbed "Melody," had been published a year ago in The New England Journal of Medicine. It was developed in 21 countries and designed to determine the efficacy of nirsevimab in healthy late preterm and term infants (35 weeks gestational age or older) who were exposed to their first RSV season. Infants received a single intramuscular injection of 50 mg for those weighing less than 5 kg or 100 mg for those weighing more than 5 kilos.
The new study was now conducted in 250 health centers in France, Germany and the United Kingdom during the 2022-2023 season. 8,000 children participated. "We are working so that we can have this alternative in the Southern Cone as soon as possible," said Sergio Montero, general manager of Sanofi Vaccines for the Southern Cone.
The U.S. CDC microscope image shows respiratory syncytial virus, which causes breathing problems in infants.
When could I arrive in Argentina? From the laboratory they told Clarín that "The dossier was presented to ANMAT for evaluation on March 31, 2023." Now we have to wait for the times of the regulatory body. It is estimated that by next year's bronchiolitis season, if the drug is approved, it could be available.
Simon Drysdale, pediatric consultant in Infectious Diseases at St. George's University Hospital and co-chief investigator of "Harmonie", explained: "Respiratory infections caused by respiratory syncytial virus (RSV) cause the hospitalization of a large number of children under 12 months each year (Note of R: according to data from the Argentine Society of Pediatrics, two out of three babies suffer from it in their first year of life ). These data reinforce the potential public health benefit of nirsevimab in terms of helping to reduce hospital stress."
The data also showed that nirsevimab reduced the incidence of hospitalizations due to severe severe lower respiratory tract disease (patients whose oxygen level is below 90% and require supplemental oxygen) linked to RSV by 75.7 percent.
This means that the impact of bronchiolitis on health systems could be significantly reduced with the use of this drug. So far in Argentina, another monoclonal antibody, palivizumab, is available for use in premature babies or babies under two years of age with congenital heart disease, and is applied in five doses at intervals of one month. In the case of nirsevimab, it is a single application.
Nirsevimab, the product of a partnership between AstraZeneca and Sanofi, has obtained special designations to facilitate the accelerated development of several regulatory agencies around the world. And it has already obtained authorization for sale in the European Union, the United Kingdom and Canada, while it is currently under regulatory review in the United States.
A mother leaves with her baby from the guard of the Children's Hospital of San Justo. Photo: Guillermo Rodríguez Adami
A "vaccine" that is not a vaccine
It should be noted that nirsevimab, although it is inoculated preventively, is not a vaccine. José Gómez Rial, head of the Immunology laboratory at the University Clinical Hospital of Santiago (Spain) explained in Gaceta Médica what this "passive immunization" consists of.
"Within the immunization formulas there are several ways; Until now we knew about the active immunization generated by vaccines, which triggers a complex network of elements that activate the immune system," he said.
What was known until now, too, was "passive immunization derived from the passage of antibodies via placenta or breastfeeding, where antibodies are transferred that protect children," Gómez Rial added. And in this case "the entire immune system is not activated. It would be like an antibody transfusion but with a fixed duration."
This protection achieved with antibodies such as nirsevimab "will protect the child for as long as these antibodies last in the body – they estimate that about six months – enhancing the protection that the mother could transfer but in a much more complete way and directed specifically to RSV".
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