An mRNA vaccine being developed to protect against COVID-19 by Pfizer and German biotech BioNTech is more than 90% effective and appears to be safe for recipients, according to early results from a Phase III trial.

“The first interim analysis of our global Phase III 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, M.D., BioNTech Co-founder and CEO.

“When we embarked on this journey 10 months ago this is what we aspired to achieve. Especially today, while we are all in the midst of a second wave and many of us in lockdown, we appreciate even more how important this milestone is on our path towards ending this pandemic and for all of us to regain a sense of normality.”

The trial investigators are aiming to recruit 44,000 participants, a total they have almost reached, and have agreed with regulatory authorities to report final results when a total of 164 confirmed COVID-19 cases have accrued across the study. This initial analysis was carried out after 94 cases had been recorded in the participants.

There are currently 47 vaccine candidates for SARS-CoV-2 in clinical trials around the world, eight of which have already reached Phase III, according to the WHO.

BioNTech is one of three key biotech’s developing mRNA vaccines to combat the SARS-CoV-2 virus – the other two are US-based Moderna (also at Phase III) and German biotech CureVac (currently at Phase II) – but BioNTech is the first to report any Phase III results.

BioNTech announced in March that it would partner with Pfizer to develop the vaccine – the two companies already had an existing agreement to co-develop an mRNA flu vaccine – and the two partners are now pushing ahead to get the vaccine on the market as soon as possible. The German biotech has also partnered with Shanghai-based Fosun Pharma to develop and distribute the vaccine in China.

The Phase III trial is randomly assigning participants who have not previously been exposed to SARS-CoV-2 to receive vaccine or placebo (1:1 ratio). It began at the end of July and has already enrolled 43,538 participants in the US, Brazil, Argentina, Germany, South Africa, and Turkey. According to the companies involved, 42% of those taking part are from “racially and ethnically diverse backgrounds.” The vaccine is split into two doses given 28 days apart and 38,955 participants have already received a second dose of the vaccine or placebo.

The initial analysis of the results shows that those in the vaccine group seem to be well protected against the virus compared with those in the placebo group, with an efficacy rate of more than 90% 7 days after being given the second dose. This measure is a primary endpoint for the study and the researchers are also measuring the efficacy at 14 days after the second dose as a secondary endpoint.

Although the focus of the study is on protection for previously unexposed individuals, the study investigators are also assessing the potential for the vaccine to be protective against SARS-CoV-2 in people who have already coronbeen exposed to the virus. They are also looking particularly at the vaccine’s ability to prevent severe COVID-19, which affects around 15% of people infected with the virus.

mRNA vaccines are new and have not yet been approved to protect against infectious diseases. They have a lot of potential and can be developed significantly faster than traditional vaccines, one reason that two of the eight companies at Phase III are developing mRNA vaccines, despite the novelty of the technology.

With any new medicine or vaccine, safety is a prime concern. This is even more important when the technology is also new, as in this case.

BioNTech and Pfizer say they have not observed any serious side effects to date, but are monitoring safety data carefully. The FDA has stipulated that 2 months of safety data, collected after participants have received the second dose, are needed for an application for Emergency Use Authorization, which the companies predict will be available before the end of November. However, participants in the study will continue to be monitored for an additional 2 years after receiving their second vaccine dose.

Both companies are also looking at their manufacturing capacity and predict they will be able to supply up to 50 million doses around the world this year and up to 1.3 billion in 2021.