In Historic Decision, FDA Approves World’s First RSV Vaccine
Aimed at adults 60 and up, the new vaccine is highly effective at preventing this common virus from causing severe and even life-threatening illness.
Almost six decades after researchers made their initial attempt to develop a vaccine for RSV (respiratory syncytial virus), the U.S. Food and Drug Administration (FDA) has approved the first vaccine to protect against serious disease caused by this common — and occasionally deadly — virus. Up until now, there have been no approved RSV vaccines anywhere in the world.
The shot, developed by the global biopharmaceutical company GSK (GlaxoSmithKline), will be marketed as Arexvy. It is aimed at people who are 60 years old and up.
“Older adults, in particular those with underlying health conditions, such as heart or lung disease or weakened immune systems, are at high risk for severe disease caused by RSV,” said Peter Marks, MD, PhD, the director of the FDA’s Center for Biologics Evaluation and Research, in a statement. “Today’s approval of the first RSV vaccine is an important public health achievement to prevent a disease which can be life-threatening and reflects the FDA’s continued commitment to facilitating the development of safe and effective vaccines for use in the United States.”
“Our focus now is to ensure eligible older adults in the U.S. can access the vaccine as quickly as possible and to progress regulatory review in other countries,” said Tony Wood, GSK’s chief scientific officer, in an announcement.
GSK expects the vaccine will be available in the United States for older adults before the 2023–2024 RSV season, which typically begins ahead of the winter months.
The U.S. Centers for Disease Control and Prevention (CDC) estimates that each year RSV leads to about 60,000 to 160,000 hospitalizations and 6,000 to 10,000 deaths among adults 65 years and older because of severe infections of the lungs and breathing passages.
“RSV is quite a big cause of hospitalizations and deaths in those over 60, so this is a big deal,” says Yvonne Maldonado, MD, a professor of global health and infectious diseases at Stanford University in California. “I think that short of the COVID vaccine, this is probably one of the biggest recent medical breakthroughs for older adults.”
RSV Vaccine Is a Powerful Means of Prevention, Trial Findings Show
Last year, GSK released late-stage study results from a trial involving about 25,000 adults age 60 and up showing that its vaccine was 82.6 percent effective overall in protecting against lower respiratory tract disease linked to RSV. The shot had even better results in protecting against severe illness with a 94.1 percent effectiveness rate.
In looking specifically at more vulnerable groups within this older population, scientists found the vaccine to be 94.6 percent effective at preventing severe illness among study participants with preexisting medical conditions, such as cardiorespiratory problems and diabetes. In the oldest age group, those 70 to 79, the inoculation showed an efficacy of nearly 94 percent.
In separate research involving more than 800 participants, investigators found that GSK’s RSV vaccine was also strongly effective when administered along with a flu shot. “The seasonality of both RSV and influenza are overlapping; vaccine co-administration could allow higher flexibility in administration, supporting vaccine coverage, while helping to protect against both infections with reduced healthcare visits,” the authors wrote in the study, which was published December 15, 2022, in Open Forum Infectious Diseases.
New RSV Vaccine Is Safe, With Only Minor Side Effects
Researchers noted that the RSV vaccine was well-tolerated and had an acceptable safety profile. For the most part, side effects were mild and not long-lasting. The most frequently observed were some pain at the point of injection, fatigue, myalgia (muscle pain), and headache.
An FDA briefing document did flag one case of Guillain-Barré syndrome considered to be related to the vaccination, occurring nine days after the individual received the shot. Guillain-Barré syndrome (GBS) is a rare nerve disorder in which the body’s immune system attacks the peripheral nervous system.
While scientists don’t fully understand why some people develop GBS, the CDC says that in very rare cases vaccines may activate the immune system to cause damage to the nerve cells.
Every year, one to two people out of every 100,000 people develop GBS, the CDC estimates. GSK data showed a GBS incidence of about 1 in 15,000 vaccines.
The FDA briefing also noted one death among the participants from acute disseminated encephalomyelitis, an intense attack of inflammation (swelling) in the brain and spinal cord. Investigators said the death was possibly related to the vaccination.
As vaccines are administered to the public, GSK, the FDA, and the CDC will continue to conduct safety monitoring.
How Does the RSV Vaccine Work?
Efforts to create an RSV vaccine go back decades. Trials in the 1960s using an inactivated virus for vaccination (similar to the method behind the flu shot) proved to be unsuccessful.
A breakthrough finally occurred when researchers published data in the journal Science in 2013 finding that vaccines could generate a highly protective response to RSV by targeting pre-fusion F protein, a part of the virus that allows it to attach to and infect human cells.
“By injecting this stabilized protein in a vaccine, we are training the immune system to produce antibodies [protective immunity] against these proteins, thus making them unable to enter the cell to produce an infection,” explains Lalitha Parameswaran, MD, MPH, a clinical assistant professor of infectious diseases and a member of the vaccine center at NYU Langone Health in New York City.
GSK’s vaccine contains pre-fusion RSV antigen along with an adjuvant, a drug designed to enhance the efficacy of the vaccine.
Why Make an RSV Vaccine for Seniors?
Older adults who get RSV are at high risk for severe disease due to age-related decline in immunity and underlying conditions, such as asthma, chronic obstructive pulmonary disease, and congestive heart failure, according to the CDC. Severe infections include bronchiolitis (inflammation of the small airways in the lung) and pneumonia (infection of the small air sacs in the lung).
In autumn 2022, the United States experienced an early and severe respiratory syncytial virus surge, putting pressure on hospitals and care centers.
RSV spreads mostly through respiratory droplets (emitted by actions like sneezing and coughing), but with many people shielded from common infections because COVID-19-related lockdowns and masking, they were not exposed to viruses as usual. As restrictions lifted, viruses came back and people appeared to be more susceptible.
More RSV Vaccines for Adults and for Children Are in the Pipeline
GSK’s is the first of several RSV vaccines that may be available soon.
Pfizer has also developed an RSV inoculation for older adults, age 60 and up. To be called Abrysvo, the shot has received the FDA advisory group’s thumb’s up, and approval from the FDA is expected soon on the heels of this GSK decision.
From data on about 37,000 participants age 60 and up, research on the Pfizer RSV vaccine concluded that it was more than 66 percent effective at preventing illness overall, and efficacy rose to 85.7 percent in preventing severe disease.
Although the first RSV vaccines to gain approval target older adults, immunizations are also coming to protect infants. A decision from the FDA on a Pfizer RSV vaccine to be administered to pregnant people, who can pass antibodies to their unborn babies, is expected in August.
Most children get RSV before age 2, usually with only mild symptoms that go away on their own. But the CDC notes that 1 to 2 out of every 100 children younger than 6 months of age with RSV infection may need to be hospitalized. Those who are hospitalized may require oxygen, IV fluids (if they aren't eating and drinking), or mechanical ventilation (a machine to help with breathing).
The Public Needs to Understand RSV’s Dangers
As RSV vaccines are expected to reach the public this year, Dr. Maldonado stresses that more research will be needed to see how long protection lasts and how well the shots work in the real world.
“I think people may have vaccine fatigue, but this is a real threat,” she says. “I think we need to do a better job of communicating the risks of this disease — it is truly a serious illness.”