FDA Approves 1st RSV Vaccine To Protect Older Adults

Older Americans this fall could get an RSV vaccine for the first time, after the Food and Drug Administration approved Wednesday a new shot from drugmaker GSK to guard against a virus that leads to thousands of hospitalizations and deaths in seniors.

"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," Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said in a statement.

The FDA's decision follows wide majority votes in favor of the safety and efficacy of GSK's Arexvy vaccine at an advisory meeting in March. 

A separate panel of the Centers for Disease Control and Prevention's vaccine advisers is expected to convene to discuss recommendations for use of the vaccine in June, a key step to guarantee insurance coverage ahead of the fall.

Data from GSK's ongoing trial published in February found a vaccine efficacy of 82.6% against RSV-related lower respiratory tract disease. 

"In older adults, RSV is a common cause of lower respiratory tract disease (LRTD), which affects the lungs and can cause life-threatening pneumonia and bronchiolitis," the FDA said.

GSK says its vaccine led to side effects that were largely "mild or moderate" and resolved within two days on average, like pain around the injection site or fatigue.

The FDA said it will require GSK to conduct a study after the shot's rollout to "assess the signals of serious risks" for two rare side effects that might be linked to the vaccine.

One is Guillain-Barré syndrome, a nervous system disorder that was seen in one trial participant, and the other is acute disseminated encephalomyelitis, a kind of brain and spinal cord swelling that two recipients developed after getting an influenza vaccine at the same time. 

Other results are expected later from studies on the safety and efficacy of co-administering Arexvy at the same time as other shots, like the stronger flu vaccines that are given annually to seniors.

Arexvy is an adjuvanted vaccine, meaning that it combines its immunogen mimicking part of the virus with an additional ingredient to trigger stronger immune responses.

The antigen builds on work by researchers at the National Institutes of Health that was hailed as one of the top 10 breakthroughs of 2013. That work would also end up forming the basis for COVID-19 vaccines used today.

Its adjuvant, called AS01, is derived from the Chilean soapbark tree and has also been used at a higher dose in the company's Shingrix vaccine.

Officials have underscored the urgency of rolling out a vaccine now, especially in the wake of fears of a "tripledemic" between COVID-19, RSV, and influenza last season.

Up to 10,000 deaths and 160,000 hospitalizations a year are caused by the virus in seniors ages 65 and older, according to estimates presented to the CDC's advisers in February, though officials also said figures range widely around this largely underdiagnosed disease.

Future seasons

GSK is still studying Arexvy over the coming seasons, which could yield more data on whether seniors should be boosted annually for RSV. 

That and other outstanding questions gave some of the FDA's advisers pause at their last meeting, though they acknowledged the positive data on the shot so far. 

The CDC's advisers may also vote only on recommendations around Arexvy for this season, effectively deferring decisions over the shot's long-term future. The panel may also vote on a narrower age cutoff for the shot. In the CDC's February meeting, a majority of the agency's work group on the topic favored recommending GSK's vaccine for adults 65 and older but not for those as young as 60, the CDC's Michael Melgar said.

Other shots

GSK's vaccine is just one of a wave of new immunizations drugmakers are racing to roll out this year for RSV.

Pfizer is also pursuing an RSV vaccine for older adults that won a narrower backing on safety and efficacy from the FDA's advisory committee earlier this year. The FDA is expected to decide on approval of Pfizer's shot by the end of this month. 

The company is also developing immunizations to guard against RSV in babies, another age group especially vulnerable to severe RSV cases, by vaccinating moms before they give birth. 

FDA's decision on that shot is expected by August, following a meeting of the FDA's vaccine advisers on May 18.

Meanwhile, AstraZeneca and Sanofi are pursuing an antibody drug to be administered directly to infants that could also guard against RSV. 

An FDA panel is scheduled to meet on June 8 to discuss the shot, with a decision over approval by the end of September.

First published on May 3, 2023 / 2:05 PM

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