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Bronchiolitis: Respiratory Syncytial Virus Vaccine for Pregnant Women Evaluated in Argentina

Argentina participated in the clinical trials to prove its efficacy and ANMAT is evaluating its authorization. The FDA endorsed the application between 32 and 36 weeks of gestation. It is intended to protect babies from birth to 6 months of age.

Respiratory syncytial virus (RSV) is highly contagious and a common cause of respiratory illness that can be life-threatening in young infants (Gettyimages)

Bronchiolitis is an acute respiratory infection that occurs most frequently in the autumn-winter months and affects mostly children under one year of age. Although it can be caused by different viruses, the most common is the Respiratory Syncytial Virus (RSV).

According to the latest National Epidemiological Bulletin, 143,887 cases of bronchiolitis in children under two years of age have been reported so far this year. In June, the outbreak of this respiratory infection exceeded previous case levels by more than 70%. outbreak of this respiratory infection exceeded by more than 70% the levels of cases prior to the the COVID-19 pandemic (which had put the circulation of other respiratory pathogens on hold). Therefore, since the end of May, the postcards were repeated in pediatric wards all over the country: full waiting rooms and several hours of delay in the attention due to the number of babies and children with bronchiolitis.

On Monday, the U.S. Food and Drug Administration (FDA) announced the approval of a vaccine for use in pregnant women against respiratory syncytial virus to prevent lower respiratory tract disease (LRTD) in infants from birth to 6 months of age.

The Abrysvo vaccine is manufactured by Pfizer and was approved in the U.S. for use between 32 and 36 weeks gestation. 32 to 36 weeks gestation and is administered as a single-dose intramuscular injection. The FDA had already approved the vaccine in May for use in patients over 60 years of age. When will it be available in Argentina?

When it will be available in Argentina

Respiratory syncytial virus is especially common in children, and most people can be expected to be infected with RSV by the time they reach the age of two (Getty)

In Argentina, the Pfizer laboratory has already submitted the documentation and requested authorization to the National Administration of Medicines, Food and Medical Technology(ANMAT). The regulatory agency is evaluating all the information submitted and there is still no estimated date of authorization.
The safety and efficacy of this vaccine in pregnant women was analyzed in ongoing international, randomized, placebo-controlled clinical studies involving 7,400 pregnant volunteers.
The clinical trials were conducted in 18 countries, one of which was Argentina. As previously reported InfobaeThe MATISSE (MATernal Immunization Study for Safety and Efficacy) trial, developed by Pfizer, is a Phase III, randomized, double-blind, placebo-controlled study designed to evaluate the efficacy, safety and immunogenicity of RSVpreF in infants born to healthy mothers, women vaccinated during pregnancy.
It enrolled about 7,400 pregnant women and began in June 2020, covering multiple RSV seasons in both the northern and southern hemispheres. The safety and efficacy of this vaccine in pregnant women was tested in clinical studies with 7,400 pregnant volunteers (Gettyimages).

Vaccine efficacy

The efficacy of the vaccine The results of the studies showed that the Abrysvo vaccine "reduced the risk of severe lower respiratory tract disease (LRTD) by 81.8% within 90 days after birth and by 69.4% within 180 days after birth." In the subgroup of pregnant women who were 32-36 weeks gestational age, immunization "reduced the risk of LRTD by 34.7% and reduced the risk of severe disease by 91.1% within 90 days after birth compared with placebo."
The most frequently reported side effects were "pain at the injection site, headache, muscle discomfort and nausea".
Following approval in the U.S., Peter Marks, director of the FDA's Center for Biologics Evaluation and Analysis said, "RSV is a common cause of illness in children, and infants are among those most at risk for severe disease, which can lead to hospitalization."
"This approval provides an option for pregnant people to protect babies from this potentially deadly disease," he added.
In a dialogue with InfobaeGonzalo Pérez Marc, pediatrician (MN 110,813) and principal investigator of the study of this vaccine being carried out at the Military Hospital of the City of Buenos Aires, was enthusiastic about the possibility of mitigating the impact of this disease: "Bronchiolitis is the main cause of viral pneumonia and mainly affects infants all over the world, especially those with risk factors. In children under 6 months of age, it has a very high rate of morbidity and intensive care hospitalizations".
Bronchiolitis is seasonal and burdens the world's health systems every winter and kills more than 100,000 children. "This is the first time that a highly effective vaccine has been developed to prevent severe disease , especially in newborns, who are most at risk. Administered to pregnant women, it has proven to be safe and effective, allowing the passage of antibodies from the mother to the baby and providing protection during the first 6 months of life", added Pérez Marc.
"Argentina, along with South Africa and the United States, was one of the leading countries in clinical development and to be part of this achievement is historic, because numerous Argentine researchers have co-authored the article that reports on this vaccine, and that highlights the importance that the country had in the development," concluded the pediatrician and researcher.

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