US-based pharmaceutical major Pfizer and German biotech firm BioNTech on Monday said that their vaccine candidate was found to be more than 90 per cent effective in preventing Covid-19 in first interim analysis of data from late-stage Phase 3 trial.

Pfizer Chairman and CEO Albert Bourla called the development "a great day for science and humanity."

While the pandemic has killed over 1.2 million people worldwide, the announcement by Pfizer and BioNTech raises hope that effective Covid-19 vaccine dose could be on its way, and if approved, before the end of this year itself.

The two companies said that their mRNA-based vaccine candidate, BNT162b2, has demonstrated evidence of efficacy against Covid-19 in participants without prior evidence of SARS-CoV-2 infection. SARS-CoV-2 is the virus responsible for Covid-19.

The analysis was conducted on Sunday by an external, independent Data Monitoring Committee (DMC) from the Phase 3 clinical study.

The case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90 per cent, at seven days after the second dose, the two companies said.

This means that protection is achieved 28 days after the initiation of the vaccination, which consists of a two-dose schedule.

As the study continues, the final vaccine efficacy percentage may vary.

The DMC has not reported any serious safety concerns and recommends that the study continue to collect additional safety and efficacy data as planned.

The data will be discussed with regulatory authorities worldwide, Pfizer and BioNTech said.

"Today is a great day for science and humanity. 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," Albert Bourla, Pfizer Chairman and CEO, said in a statement.

"We are reaching this critical milestone in our vaccine development programme at a time when the world needs it most with infection rates setting new records, hospitals nearing over-capacity and economies struggling to reopen.

"With today's news, 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," Bourla added.

The Phase 3 clinical trial of BNT162b2 began on July 27 and has enrolled 43,538 participants to date, 38,955 of whom have received a second dose of the vaccine candidate as on November 8.

The trial is continuing to enroll and it also will evaluate the potential for the vaccine candidate to provide protection against Covid-19 in those who have had prior exposure to SARS-CoV-2, as well as vaccine prevention against severe Covid-19 disease.

"We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks," Bourla said.

Pfizer and BioNTech said they are continuing to accumulate safety data and currently estimate that a median of two months of safety data following the second (and final) dose of the vaccine candidate will be available by the third week of November.

Along with the efficacy data generated from the clinical trial, the two companies are working to prepare the necessary safety and manufacturing data to submit to the US Food and Drug Administration (FDA) to demonstrate the safety and quality of the vaccine product produced.

Based on current projections, Pfizer and BioNTech expect to produce globally up to 50 million vaccine doses this year and up to 1.3 billion doses in 2021.

"The first interim analysis of our global Phase 3 study provides evidence that a vaccine may effectively prevent Covid-19. This is a victory for innovation, science and a global collaborative effort," said Ugur Sahin, BioNTech co-founder and CEO.

More than 200 vaccines to protect against the virus are being developed by scientists around the world in a process that is taking place at unprecedented speed.