Potent RSV vaccine data lifts hope after years of futility

Vaccinating pregnant women could protect newborns from a common but deadly respiratory virus called RSV, according to a new study.

Preliminary results hope that after decades of failure and frustration, a vaccine against RSV may finally be close to becoming a reality.

Pfizer said Tuesday that a large international study found that vaccinations for expectant mothers were nearly 82% effective in preventing severe cases of RSV during the baby’s most vulnerable first 90 days of life. announced. At 6 months of age, the vaccine was proven to be 69% effective against serious illness and had no safety issues for mothers or babies.

“Mothers are constantly giving their babies antibodies,” said virologist Kenna Swanson, vice president of viral vaccines at Pfizer. just place it in a better position.

The quest for a vaccine is not just for protecting infants. RSV is also dangerous for older people, and Pfizer and its rival GSK recently announced that competing injectables have proven to protect older people.

None of the findings are helpful this year, when an early RSV surge is already congesting children’s hospitals. But they put forward the prospect that one or more vaccines may be available before his RSV season next fall.

Dr. William Schaffner, an infectious disease specialist at Vanderbilt University, said: “We are invading.”

Tuesday’s data was reported in a press release and has not been vetted by an independent expert.

Here we look at the long quest for an RSV vaccine.

What is RSV?

For most healthy people, RSV, or respiratory syncytial virus, is like the common cold. The virus can infect deep within the lungs and cause pneumonia, which can inflame the small airways in infants and interfere with breathing.

Approximately 58,000 children under the age of five are hospitalized for RSV in the United States each year, and hundreds die. Among adults over the age of 65, about 177,000 are hospitalized with her RSV, and 14,000 die each year.

Worldwide, RSV kills about 100,000 children annually, mostly in poor countries.

Why are there no vaccines?

The tragedy of the 1960s set the whole field back. Using the approach that led to the first polio vaccine, the scientist created his RSV vaccine by growing the virus in the lab and then killing it. However, in children’s tests, not only was the vaccine not protective, but adolescents infected with RSV after vaccination had worse outcomes: two died.

“For 20 years, despite advances in science, no one has come close to developing an RSV vaccine,” Schaffner said.

He noted that even today’s latest RSV vaccine candidate was first tested in the elderly, not in children.

How did development take off?

Modern vaccines tend to target the outer surface of the virus, which is what the immune system recognizes when bacteria enter. In the case of RSV, its target is the so-called F protein, which helps the virus stick to human cells. Again, there were hurdles. That protein is a shape-shifter that rearranges its morphology before and after it “fuses” into the cell.

According to structural biologist Jason McClellan of the University of Texas at Austin, the immune system forms effective RSV-fighting antibodies only when it finds what it calls a pre-fusion version of the protein.

In 2013, while working at the National Institutes of Health, McClellan and virologist Bernie Graham figured out the correct shape and figured out how to freeze it in that shape. That discovery paved the way for today’s development of various RSV vaccine candidates.

(Coronaviruses also hide in shape-changing surface proteins, so the same finding was key to the hugely successful COVID-19 vaccine.)

What’s in your pipeline?

Several companies are developing RSV vaccines, but Pfizer and GSK are the most advanced. Both companies recently reported a final-stage test in the elderly. Although the competing vaccines are made somewhat differently, each has proven highly effective against particularly serious diseases. approval will be sought.

The data on older people “looks great,” said McClellan, who has been following vaccine development closely. “I think we’re on the right track.”

And if successful, vaccinating pregnant women could be “a win for two, not one,” by providing protection for both mother and baby, says the University of Maryland School of Medicine. said Dr. Wilbur Chen of

Pfizer’s maternal vaccine is the same recipe that has been successfully tested in the elderly, and it plans to seek Food and Drug Administration approval for these vaccinations by the end of the year.

The new study included 7,400 pregnant women in 18 countries, including the United States, and spanned multiple RSV seasons. Preliminary results reported on Tuesday show the vaccine is most effective against severe disease. For mild illness, efficacy was 51% to 57% for her, which fell short of the statistical requirements of the study, but Pfizer says it could be clinically more effective as it may reduce the number of clinic visits. says it makes sense.