By Markson Omagor
Yesterday, the 9th November 2020, Pfizer Inc and BioNTech SE announced that their Covid19 vaccine candidate had demonstrated a 90% efficacy against Covid-19.
The announcement followed the first interim efficacy analysis conducted on November 8, 2020 by an external, independent Data Monitoring Committee (DMC) from the Phase 3 clinical study.
The 90% efficacy of the BNT162b2 vaccine is based on COVID-19 in participants without prior evidence of SARS-CoV-2 infection.
In a press statement, the Companies revealed that after discussion with the FDA, it was agreed that they drop the 32-case interim analysis and conduct the first interim analysis at a minimum of 62 cases.
Upon the conclusion of those discussions, the evaluable case count reached 94 and the DMC performed its first analysis on all cases. The case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90%, at 7 days after the second dose.
The implication is that protection is achieved 28 days after the initiation of the vaccination, which consists of a 2-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 lingering Questions
Will the vaccine be effective on persons with prior exposure to Covid-19?
As of today, studies will continue to evaluate the potential for the vaccine candidate to provide protection against COVID-19 in those who have had prior exposure to SARS-CoV-2.
Will the vaccine’s efficacy against severe Covid-19 cases be high?
This question is also yet to be answered as the manufacturers assert that they need more studies and time to ascertain the efficacy of their vaccine against this group of cases.
How effective is the vaccine on older persons?
The new results also don’t tell us whether older people will get strong protection from the vaccine. Pfizer and BioNTech’s clinical trial includes people over age 65, so it will eventually provide this crucial information. Early clinical studies have suggested that older people produce a weaker immune response to coronavirus vaccines. But with such strong preliminary evidence, it’s possible that they will still get strong protection from a vaccine.
History also suggests any vaccine could be less successful in old people because an aged immune system does not respond as well to immunisation. We see this every year with the annual flu jab.
It may be possible to overcome this by either giving multiple doses or giving it alongside a chemical (called an adjuvant) that gives the immune system a boost.
What about children?
Another open question is whether children will get protection from the vaccine. The trial run by Pfizer and BioNTech initially was open to people 18 or older, but in September they began including teenagers as young as 16. Last month, they launched a new trial on children as young as 12 and plan to work their way to younger ages.
How many people need to be vaccinated in order for the virus to be defeated?
It is hard to know without knowing how effective the vaccine is going to be.
It is thought that 60-70% of the global population need to be immune to the virus in order to stop it spreading easily (known as herd immunity) – in other words, billions of people, even if the vaccine works perfectly. And yet the companies estimate that they can only be able to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021.
What is the cost of the jab and who will foot it?
In the press release, the manufacturers did not talk about the cost probably because the vaccine is yet to be cleared by FDA and the WHO.
However, UK is said to have ordered more than 10 million doses by the end of 2020, with a further 30 million doses already ordered. This means, individual countries will meet the costs of the vaccine although there are efforts to have the vaccine paid for or at least subsidized for the poorer countries.
For how long will a vaccinated person be able to fight off the infection?
The manufacturers have said that participants will continue to be monitored for long-term protection and safety for an additional two years after their second dose. So this question has not been answered as of now.
“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,” said Dr. Albert Bourla, Pfizer Chairman and CEO.
“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 Prof. Ugur Sahin, BioNTech co-founder and CEO.
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 of November 8, 2020.
Approximately 42% of global participants and 30% of U.S. participants have racially and ethnically diverse backgrounds. The trial is continuing to enroll and is expected to continue through the final analysis when a total of 164 confirmed COVID-19 cases have accrued.
In addition to the primary efficacy endpoints evaluating confirmed COVID-19 cases accruing from 7 days after the second dose, the final analysis now will include, with the approval of the 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.
Pfizer and BioNTech 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 – 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.
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 we expect to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021.