Pfizer said the vaccine had no serious side effects and that the company will apply for emergency use authorisation from US regulators within a matter of days."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," said Pfizer CEO Albert Bourla.Last week the company had announced that its vaccine, jointly developed with BioNTech, was 90% effective in preventing Covid-19 infections in the ongoing Phase 3 trials.Protection in patients was achieved seven days after the second of two doses, and 28 days after the first, according to preliminary findings.

"The first set of results from our Phase 3 Covid-19 vaccine trial provides the initial evidence of our vaccine's ability to prevent COVID-19," Bourla had said last week."We are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis. We are reaching this critical milestone in our vaccine development program at a time when the world needs it most," he had added.Pfizer has also launched a pilot delivery programme for its experimental vaccine in four US states. The vaccines must be shipped and stored at -70 degrees Celsius, significantly below the standard for vaccines of 2-8 degrees Celsius.

"We are hopeful that results from this vaccine delivery pilot will serve as the model for other US states and international governments, as they prepare to implement effective COVID-19 vaccine programs," Pfizer said in a statement on Monday.

It picked Rhode Island, Texas, New Mexico, and Tennessee for the program after taking into account their differences in overall size, diversity of populations, immunization infrastructure, and need to reach individuals in varied urban and rural settings. The four states will not receive vaccine doses earlier than other states by virtue of the pilot, nor will they receive any differential consideration, Pfizer said.

Across much of the globe, Covid-19 infections rates are soaring to record highs, with hospital intensive care units filling up and death tolls mounting as well. Based on supply projections, the companies said they expect to supply up to 50 million vaccine doses globally in 2020, and up to 1.3 billion doses in 2021.

The World Health Organization earlier hailed as "encouraging" Pfizer and BioNTech's announcement. "We welcome the encouraging vaccine news from @pfizer & @BioNTech_Group & salute all scientists & partners around the who are developing new safe, efficacious tools to beat #COVID19," WHO director Tedros Adhanom Ghebreyesus had said in a tweet.