Pfizer and BioNTech's COVID-19 vaccine shows 90% efficacy

Pfizer and BioNTech have announced that their SARS-CoV-2 vaccine candidate has proved more than 90% effective in preventing COVID-19 in participants without prior evidence of infection. The results are based on initial data from the companies’ Phase 3 clinical study of 43,538 participants, including 94 confirmed cases of COVID-19.

The Phase 3 clinical trial of the mRNA vaccine candidate BNT162b2 began on 27 July and has enrolled 43,538 participants to date, 38,955 of whom had received a second dose of the vaccine as of 8 November. An external, independent data monitoring committee (DMC) conducted the interim analysis once 94 evaluable cases of COVID-19 had accrued; the trial is continuing to enrol and is expected to continue through the final analysis when a total of 164 cases have accrued.

The case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90%, at seven days after the second dose, the companies claim. 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 study 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. In addition to the primary efficacy endpoints evaluating confirmed COVID-19 cases accruing from seven days after the second dose, the final analysis now will include, with the approval of the US FDA, new secondary endpoints evaluating efficacy based on cases accruing 14 days after the second dose as well. The companies believe that the addition of these secondary endpoints will help align data across all COVID-19 vaccine studies and allow for cross-trial learnings and comparisons between these novel vaccine platforms.

“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,” said Pfizer Chairman and CEO Dr Albert Bourla. “We are reaching this critical milestone in our vaccine development program 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. We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks.”

Pfizer and BioNTech currently estimate that a median of two months of safety data following the second (and final) dose of the vaccine candidate — the amount of safety data specified by the FDA in its guidance for potential Emergency Use Authorization — will be available by the third week of November. Additionally, participants will continue to be monitored for long-term protection and safety for an additional two years after their second dose.

Along with the efficacy data generated from the clinical trial, Pfizer and BioNTech are working to prepare the necessary safety and manufacturing data to submit to the FDA to demonstrate the safety and quality of the vaccine product produced. Based on current projections, the companies expect to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021.

It’s particularly good news for the Australian Government, which announced just a few days ago that it had secured 10 million doses of the mRNA vaccine, along with 40 million doses of a protein vaccine from Novavax. This is in addition to the government’s existing commitments to purchase the vaccine candidate AZD1222 from the University of Oxford and AstraZeneca, and the local candidate UQ-CSL V451 from The University of Queensland and CSL (Seqirus). CSL in fact has contracts with AstraZeneca and the Australian Government to manufacture approximately 30 million doses of AZD1222 — a manufacturing process that began just yesterday at its facility in Broadmeadows, Victoria.

The CSL manufacturing process will start with the thaw of vials containing vaccine cells. The cells — frozen under liquid nitrogen to preserve their integrity — need to be thawed in preparation for replication in the bioreactors at the Broadmeadows facility. After growing in the bioreactors, the vaccine is then filtered and purified leaving just the antigen, or vaccine product. It is then ready for final formulation and filling into dosage vials.

During 2020–2021, CSL will manufacture eight large-scale batches of vaccine drug substance. Should the vaccine demonstrate its safety and efficacy in clinical trials that are currently underway, it is anticipated that it will require a two-dose per person regime. The vaccine will not be released for use until the relevant clinical trial and manufacturing data are reviewed and approved by the Therapeutic Goods Administration (TGA), but first doses are expected in the first half of 2021.

Multiple doses of the UQ-CSL V451 vaccine candidate have already been manufactured at the Broadmeadows facility and are being held in readiness to progress the vaccine to Phase 2b/3 clinical trials, once Phase 1 data has been released and analysed.

“This is an important milestone and marks the end of many months of around-the-clock preparation by our skilled personnel globally within CSL Behring, Seqirus and research and development,” said CSL’s Chief Scientific Officer, Dr Andrew Nash. “Both campaigns are still technically challenging, but at this time we are tracking well and expect to produce the AZD1222 and the UQ-CSL V451 vaccine for Australia by mid-2021.”

Image credit: ©stock.adobe.com/au/terovesalainen

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