The first RSV vaccine for expectant mothers was approved by American regulators on Monday so that their children will be born protected against the frightening respiratory infection.

Every fall and winter, RSV is known for packing hospitals with infants who are wheezing. 

The maternal vaccination developed by Pfizer to prevent a severe case of RSV between the ages of birth and six months has been approved by the Food and Drug Administration.

The next stage is for the Centers for Disease Control and Prevention to recommend using the Abrysvo vaccine while pregnant, according to The Associated Press.

RSV is an annoyance similar to cold for the majority of healthy people, but it can be fatal for the very young. It either causes pneumonia or inflames a baby's small airways, making breathing difficult. 

Between 58,000 and 80,000 children under the age of five are hospitalized annually in the United States alone due to the respiratory syncytial virus, and several hundred of them pass away.

The RSV season last year was very severe in the United States and sickened infants far earlier than usual, in the summer.

Babies immune systems are undeveloped at birth, so they rely on their mothers' protection for the first few months. 

Read also: Late-Stage RSV Vaccine Trials Found 82% Effective in Infants

How It Works for Pregnant Women

The RSV vaccine works by giving a single injection late in pregnancy, which provides the expectant mother ample time to generate virus-fighting antibodies that travel to the fetus through the placenta and are ready to work when the baby is born.

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NEW YORK, NEW YORK - APRIL 10: The Pfizer company logo is displayed as traders work on the floor of the New York Stock Exchange during morning trading on April 10, 2023, in New York City.

Pregnant women also transmit immunity to other infections in this manner. Long advised to get vaccinated against the flu, whooping cough, and more recently, the COVID-19 virus, are pregnant women.

In the Pfizer trial, there were over 7,400 pregnant women and their offspring. A moderate RSV infection was not prevented by maternal immunization, but a severe case during the first three months of a baby's life was. It was still shown 69 percent effectiveness against serious sickness at age 6 months.

Most vaccine responses were soreness and exhaustion at the injection site. In the research, there was a tiny difference in the number of preterm births - just a few weeks early - between mothers who received the vaccine and those who received a placebo shot, which Pfizer has stated was accidental. 

The vaccination should only be administered between 32 and 36 weeks of pregnancy, a few weeks later than during the research trial, according to the FDA in order to avoid the potential.

Pfizer estimated that if enough pregnant women receive the vaccine, the United States might avoid up to 20,000 newborn hospitalizations and 320,000 medical visits per year.

Most vaccine responses were soreness and exhaustion at the injection site. In the research, there was a tiny difference in the number of preterm births - just a few weeks early - between mothers who received the vaccine and those who received a placebo shot, which Pfizer has stated was accidental. 

The vaccination should only be administered between 32 and 36 weeks of pregnancy, a few weeks later than during the research trial, according to the FDA in order to avoid the potential.

Pfizer estimated that if enough pregnant women receive the vaccine, the United States might avoid up to 20,000 newborn hospitalizations and 320,000 medical visits per year.

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