FDA approves GSK's RSV vaccine for older adults, world's first shot against virus

The Food and Drug Administration on Wednesday approved an RSV vaccine produced by GlaxoSmithKline for use on adults ages 60 and older.

The approval, the first ever globally by a regulatory body for an RSV vaccine, is a decisive victory for GSK in a race against drugmakers Pfizer and Moderna to bring to market a shot that targets the respiratory syncytial virus.

Shares of GSK rose nearly 2% Wednesday following the approval.

GSK's chief scientific officer Tony Wood said in a statement the decision "marks a turning point" in the company's effort to reduce the "significant burden" of RSV.

The company will now focus on ensuring eligible older adults in the U.S. can access the vaccine "as quickly as possible," he said. GSK will also work toward regulatory review and approval of the shot in other countries.

London-based GSK during an earnings presentation last week said it has "millions" of doses of the RSV vaccine ready to ship. 

The company plans to meet in June with the federal Centers for Disease Control and Prevention's vaccine advisory committee to hash out potential vaccination schedules for the U.S., according to that presentation.

GSK's shot is also inching closer to approval in the European Union. Last week, the European Medicines Agency recommended that the company's vaccine be approved by the EU for older adults. 

The shot would help countries combat the next RSV season in the fall. 

The U.S. suffered an unusually severe RSV season last year. 

Cases of the virus in children and older adults overwhelmed hospitals across the country, largely because the public stopped practicing Covid pandemic health measures that had helped keep the spread of RSV low. 

RSV usually causes mild, cold-like symptoms. But each year the virus kills 6,000 to 10,000 seniors and a few hundred children younger than 5, according to the CDC. 

The FDA said the approval of GSK's vaccine was based on data from a phase three trial on older adults. 

In March, an independent panel of advisors to the FDA recommended the shot based on those trial results, which found the shot nearly 83% effective at preventing lower respiratory tract disease caused by RSV. Disease was defined as two or more symptoms including shortness of breath, wheezing, cough, increased mucus production, crackles, low oxygen saturation, or need for oxygen supplementation. 

The independent panel unanimously said the efficacy data on GSK's vaccine was sufficient. 

But the advisors also flagged potential safety issues over a nervous system disorder, Guillain-Barre syndrome, that may be tied to the shot.

A 78-year-old woman in Japan was diagnosed with Guillain-Barre syndrome nine days after receiving GSK's vaccine, according to an FDA briefing document. She was hospitalized for six months before being released.

The document said the woman was the only case of Guillain-Barre syndrome out of the more than 12,000 people who received the shot. 

GSK said in February that there is insufficient evidence to confirm the woman got Guillain-Barre as a result of GSK's shot.

But the FDA said at the time that it considers the case to be related to GSK's vaccine. 

On Wednesday, the agency said it will require GSK to conduct a study to further assess the risk of Guillain-Barre syndrome and another side effect observed in a clinical trial that co-administered the RSV shot with a flu vaccine.

Guillain-Barre syndrome is a rare disorder in which the immune system attacks its own nerves, causing muscle weakness and sometimes paralysis. Most people recover completely from the disorder, but some cases can be fatal or have lasting effects.

The rate of Guillain-Barre syndrome is typically one to two cases per 100,000 people each year in the U.S., according to the National Organization for Rare Disorders.

The FDA flagged the disorder as a potential safety issue with Pfizer's RSV vaccine for older adults.

Two people developed Guillain-Barre syndrome after receiving Pfizer's shot in a late-stage clinical trial with more than 20,000 vaccine recipients.

Pfizer in February said it will conduct a safety study to further assess Guillain-Barre syndrome if the FDA approves its vaccine.

The pharmaceutical company is hoping to win that approval later this month.

No cases of Guillain-Barre syndrome were identified during a clinical trial of Moderna's RSV vaccine.

Moderna plans to file an application for FDA approval during the first half of this year.