A man enters the employee entrance of the Pfizer World Headquarters building in the Manhattan borough of New York, U.S., November 23, 2015. Image Credit: Reuters

Pfizer announced on Wednesday that its vaccine trial has been completed, with "95% effectiveness." The high success rate of the large-scale clinical tests is expected to bring coronavirus under control. Pfizer's BNT162b2 vaccine is one the leading coronavirus vaccine candidates. It was developed by Pfizer and BioNTech. Officials said results will be submitted for regulatory approval "within days," the companies announced Wednesday, after their final analysis suggested the drug was even more effective than previously thought.

The US pharma giant and its German partner said their Phase 3 trial was now complete, and that it found the vaccine was 95 percent effective at preventing symptomatic COVID-19 — up from the 90 percent announced last week.

Vials with a sticker reading, "COVID-19 / Coronavirus vaccine / Injection only" and a medical syringe are seen in front of a displayed Pfizer logo. Image Credit: Reuters

There have been no serious side effects among the 41,135 adults who received two doses, the companies said in a joint statement. The most common reactions were that 3.7 percent of participants experiencing fatigue and 2 percent had a headache, it said.

Data release awaited

Experts have urged caution, particularly before more data is publicly released. And distributing any vaccine to the United States and wider world will also be a monumental logistical challenge. But nevertheless the news has been treated as a glimmer of hope in an otherwise bleak year, as global deaths have risen above 1.3 million, almost 250,000 of them in the United States. If approval was given this year, that would beat expectations in what is usually a glacially slow process.

"The study results mark an important step in this historic eight-month journey to bring forward a vaccine capable of helping to end this devastating pandemic," Dr. Albert Bourla, Pfizer chairman and CEO, said in the statement. "With hundreds of thousands of people around the globe infected every day, we urgently need to get a safe and effective vaccine to the world."

Pfizer and BioNTech said they will now submit a request "within days" for emergency use authorization with the U.S. Food and Drug Administration, while sharing their data with regulators in Europe and elsewhere. The news comes days after Moderna, a biotech company based in Massachusetts, said early analysis from its own Phase 3 trial suggested its vaccine candidate was 94.5 percent effective.

Doubly encouraging, experts say, is that the Pfizer-BioNTech and Moderna candidates both use the same cutting-edge technology: messenger code called "RNA" that's injected into the body and tricks it into producing an immune response.

'95% effective': Where it comes from

The figure of 95 percent comes from Pfizer and BioNTech analyzing 170 confirmed cases among the 40,000-plus people involved in the trial. Just eight people who were given the vaccine got sick, compared with 162 who were given a placebo. Pfizer says it plans to manufacture 50 million doses this year and 1.3 billion in 2021, using facilities in Missouri, Massachusetts, Michigan and Belgium. Its vaccine must be kept at minus 94 degrees Fahrenheit.

Pfizer has developed a super-cool storage unit packed with dry ice, which it says will help transport the vaccine around the world, including to remote places. But experts warn that in practice keeping such a vaccine at such low temperatures will be an unprecedented supply-chain challenge.