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New RSV Vaccine: How to Protect Your Family Against RSV This Season

September 13, 2023
A baby lays on an exam table

The FDA recently approved an RSV vaccine that will be given to pregnant women to protect infants. RSV vaccines for older people and a new monoclonal antibody for babies will also be available this year.

This fall, as many Americans will make appointments to get their flu shots and COVID-19 boosters, new vaccines will offer protection to infants and adults at high risk of another common illness: respiratory syncytial virus (RSV).

The U.S. Food and Drug Administration (FDA) recently approved the first-ever maternal vaccine intended to protect newborns against RSV. The vaccine is available to women during late pregnancy to reduce the risk of severe RSV infection — it is now awaiting evaluation from the Centers for Disease Control and Prevention (CDC). 

In the meantime, families will have access to a newly approved monoclonal antibody that is recommended for all infants less than 24 months old.  

Furthermore, the FDA has approved two RSV vaccines for older adults and the CDC recently recommended that anyone aged 60 years or older be eligible to receive them, making this the first year in which people can protect themselves against all three viruses: RSV, influenza and COVID-19.

Below, Dr. James Versalovic, Pathologist-in-Chief at Texas Children’s Hospital and Director of Texas Children’s Microbiome Center, answers questions about the upcoming preventative options available for pregnant women, babies and older adults.

What is RSV?

RSV is a very common respiratory virus that causes mild, cold-like symptoms in most people (runny nose, fever and cough). When RSV becomes a lower respiratory tract infection, however, it can lead to life-threatening complications. 

“When it moves into the lower part of the lungs, it can lead to severe infection that requires supportive care,” said Dr. Versalovic. “Among other things, it can cause bronchiolitis and life-threatening pneumonia, and in severe cases, this virus may result in infections requiring ICU hospitalizations and mechanical ventilator support.”

RSV is so contagious that avoiding it altogether is almost impossible — the CDC estimates that the vast majority of children will contract RSV by the time they turn 2 years old. RSV is typically transmitted through close contact with someone who is infected and many people are not even aware they have it.

A seasonal illness, RSV starts in the fall and peaks in the winter — but that pattern seems to be changing. 

“It's hard to know when RSV will strike during the year these days,” said Dr. Versalovic. “Since 2021, we've been confronted with RSV surges at atypical times during the year. So we need to be vigilant about tracking RSV infections at Texas Children's and advising parents when we must go on high alert.” 

Who is most at risk?

Infants are particularly susceptible to RSV, because their immune systems are still developing. The risk of RSV-associated lower respiratory tract disease (LRTD) is highest during the first 12 months. According to the CDC, RSV is the leading cause of infant hospitalization in the U.S. Each year, RSV causes up to approximately 80,000 hospitalizations and 300 deaths in children under 5 years old.

Older adults — and those who have preexisting conditions like asthma and congestive heart failure — are also at risk.

“Although RSV is seen as a threat to the very young — and rightly so — it actually has a much bigger impact on the elderly in terms of raw numbers,” said Dr. Versalovic.

In fact, the CDC reports up to 160,000 hospitalizations among older adults and up to 10,000 deaths each year because of RSV infections.

What you need to know 

In 2023, the FDA gave full approval to two RSV vaccines — Arexvy from GlaxoSmithKline and Abrysvo from Pfizer. Both are administered as a single dose and both are highly effective. In clinical trials, GSK’s vaccine was 88% effective against severe RSV infection; Pfizer’s vaccine was 85% effective.

“Both vaccines use traditional platforms similar to a flu shot, not to be confused with mRNA technology used in COVID-19 vaccines introduced by Pfizer and Moderna,” said Dr. Versalovic. “They work by introducing RSV protein into the body to stimulate an immune response.” 

Although the RSV vaccines are not without side effects, doctors believe the benefits outweigh the risks for older adults, especially those with underlying health conditions or weakened immune systems. 

RSV vaccines can be administered at the same time as other vaccines.

RSV vaccine for pregnant women

The advisory panel of Abrysvo, Pfizer’s vaccine for older people, recommended its use for pregnant women, and the FDA approved it last month. Abrysvo will be given to pregnant women in their late second or third trimester of pregnancy to pass on RSV protection to their fetuses — and the antibodies will continue to provide protection to babies for up to six months after delivery. 

The safety and effectiveness of Abrysvo for immunization of pregnant women to prevent lower respiratory tract disease (LRTD) and severe LRTD caused by RSV in infants were evaluated in multiple clinical studies. Abrysvo reduced the risk of severe LRTD by 81.8% within 90 days after birth, and 69.4% within 180 days after birth. 

The most commonly reported side effects were pain at the injection site, headache, muscle pain and nausea. 

The FDA is requiring Pfizer to conduct postmarketing studies to assess the risk of other, potentially more serious side effects. It is not yet clear when the vaccine will become widely available.  

The new monoclonal antibody

In July, the FDA approved Beyfortus, a new monoclonal antibody developed by Sanofi and AstraZeneca — the first new RSV monoclonal antibody developed in over 20 years. Monoclonal antibodies are laboratory-made proteins that mimic the immune system’s ability to fight off pathogens.  

Three clinical trials supported the safety and efficacy of Beyfortus. A phase 3 trial showed that it reduced RSV-triggered lower respiratory tract infections that require medical care by 76.4% and cut RSV hospitalizations by 76.8%. 

One dose of Beyfortus, administered as a single injection, may provide protection during the RSV season, and as a result, the FDA has approved its use for all children up to 24 months of age.

“This is a big development,” said Dr. Versalovic. “The problem with the old monoclonal antibody was that it was only available for a narrow subset of children who were at high risk of disease. We now have a way to reduce the impact of RSV on all children under 2 years of age. This will be extremely helpful this year.” 

Monoclonal antibodies work differently than vaccines. “The key advantage is that you get the antibodies directly into infants and children under 24 months of age,” said Dr. Versalovic. “With vaccines, it takes time to produce antibodies to protect you against whatever the vaccine is for. The monoclonal antibody is injected directly into the body and so bypasses that step, conferring protection right away.” 

RSV is nothing new — but this season, we have a host of new weapons to combat it, which will hopefully reduce its harmful impact on infants, older adults and the health care system as a whole.