BioNTech stock popped Wednesday after the Food and Drug Administration released Pfizer's argument in support of offering Covid booster shots six months following the second dose.

Recent data suggest the vaccine is roughly 84% effective after four months, down from 96% in the week after the second dose, Pfizer said in the document. The FDA posted the briefing ahead of a key meeting on Friday. An independent panel of experts will debate Pfizer's booster shot plan before making a nonbinding recommendation to the full FDA.

The meeting is a key step toward launching booster shots next Monday — a plan the White House Covid task force announced last month. The plan would start offering third dose of the Pfizer-BioNTech and Moderna vaccines eight months after the second dose. The FDA has already authorized booster doses in some immunocompromised people.

On the stock market today, BioNTech stock jumped 6.1% to 355.25. Pfizer stock inched up 0.1% to 44.77.

BioNTech Stock: Will FDA Approve Boosters?

Recent data suggest vaccine effectiveness is waning. But Pfizer didn't blame the delta variant. It cited a study performed at Kaiser Permanente in Southern California.

"Effectiveness against delta infections was more than 90% early on," Pfizer said. "Vaccine effectiveness decreases with increasing time since being fully vaccinated, irrespective of variant, and effectiveness against delta variant hospitalizations remained high over the entire study period."

On Friday, the FDA says it will discuss whether Pfizer has presented sufficient data "to support safety and effectiveness of a booster dose" six months following the second dose. BioNTech stock could pop against if the booster dose is approved.

Pfizer's application is for booster shots in people ages 16 and older — the population in which its vaccine is now fully approved. The original two-dose vaccine is also authorized in people ages 12-15.

Pfizer notes the primary two doses are still very effective against severe illness requiring hospitalization and death. Part of the FDA's criteria for approving the booster dose will depend on "the effectiveness of booster vaccination in preventing important Covid-19-related outcomes in individuals who have already received a primary vaccination series."

BioNTech stock analysts call for more than $19.5 billion in full-year sales. That number could rise if the FDA approves a third dose of the company's vaccine.

Experts Split On The Booster Shot Debate

Recently, a group of experts argued against booster doses. Instead, they favored getting vaccines out to unvaccinated people. In the U.S., about 47% of eligible people are unvaccinated, the Centers for Disease Control and Prevention estimates.

Dr. Marion Gruber, director of the FDA's Office of Vaccines Research and Review, was among those arguing against booster shots in a paper published in the medical journal, The Lancet. Gruber will speak during the meeting Friday, introducing the booster topic on behalf of the FDA.

Enthusiasm for vaccine stocks briefly peaked in August. But shares of BioNTech and Moderna are restarting their runs.

On a year-to-date basis, BioNTech stock has surged by triple digits. Shares have a top-notch Relative Strength Rating of 99, according to IBD Digital. This puts BioNTech stock in the leading 1% of all stocks in terms of 12-month performance.

Follow Allison Gatlin on Twitter at @IBD_AGatlin.