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expert reaction to announcement by Pfizer that they have concluded the Phase III study of their COVID-19 vaccine candidate after demonstrating 95% efficacy

Pfizer and BioNTech have announced that they have concluded phase 3 study of their COVID-19 vaccine candidate, demonstrating 95% efficacy.


Dr Zoltán Kis, Research Associate at the Future Vaccine Manufacturing Hub, Imperial College London, said:

“It is a phenomenal achievement to reach this stage of vaccine development against a new disease less than a year after the start of the COVID-19 vaccine development programs. This has been made possible largely due to the use of new transformative platform technologies, such as the RNA vaccine platform.

“Today’s press release from Pfizer is another piece of very promising news, both for developing a COVID-19 vaccine, and for the RNA platform technology. Once fully developed and validated, the RNA platform technology puts us in a much better position to develop and produce vaccines substantially faster against future viral outbreaks, including outbreaks caused by both existing and currently unknown, future viral pathogens. This is possible because any RNA sequence can be produced using the same production, purification and formulation processes – only the template DNA needs to be changed. Thus, by using the RNA vaccine platform technology, vaccine candidates against virtually any disease can be produced.

“This is very advantageous when compared to existing technologies whereby each conventional vaccine would usually require its own unique production process to be developed. In addition, conventional vaccine production requires larger scale and higher cost facilities compared to a facility housing the RNA vaccine production platform. Thus, developing and producing RNA vaccines can save time and costs in the future. Production volumes and production rates can be substantially increased if vaccine formulations with lower amounts of RNA per vaccine dose can be used.

“In this press release, Pfizer stated that it expects to produce 1.3 billion vaccine doses by the end of 2021. Considering the global population (currently at around 7.8 billion) and the fact that two doses are required per person, 1.3 billion doses is not even close to meeting the global COVID-19 vaccination demand. The manufacturing of these vaccines can limit the rate at which the global population will become immune and the rate by which we overcome the COVID-19 pandemic. Therefore, vaccines with a lower amount of RNA per dose will have a substantial manufacturing advantage. Moderna’s COVID-19 vaccine candidate has 100 micrograms of RNA per dose, whereas the BioNTech/Pfizer vaccine candidate has 30 micrograms of RNA per dose.

“The low temperatures required for distributing the Pfizer/BioNTech and Moderna COVID-19 vaccines (if approved by regulators) can make distribution challenging, in particular in low and middle income countries, and in countries with hot climates and/or a lack of adequate infrastructure. The Moderna COVID-19 vaccine candidate is shipped at -20 °C. The Pfizer/BioNTech vaccine candidate needs to be shipped at even lower temperatures of -70 °C, which is even more challenging, although special temperature-controlled thermal shipper boxes utilizing dry ice have been developed for shipping the Pfizer/BioNTech vaccines. Thus distributing these vaccines globally might pose additional challenges for the equitable distribution of vaccines.

“The COVID-19 pandemic is a global healthcare crisis, and a global approach is required to resolve it. Thus, it is important to immunise people in all countries in the world for the following reasons:

1) To reduce mortalities globally (by giving the vaccine to the most vulnerable globally)

2) To stop the spread of the disease and prevent additional waves of outbreaks

3) And to be able to open up borders and allow travel between countries.

“A lot has been achieved so far with the development of COVID-19 vaccines, but there are numerous challenges ahead for overcoming this pandemic. These include manufacturing and distribution challenges as well as challenges related to administering the vaccine to people.”


Dr Charlie Weller, Head of Vaccines at the Wellcome Trust, said:

“This reported additional data is another bright moment in what has been a dark year. Today’s update from Pfizer/BioNTech on the efficacy of their vaccine is highly encouraging. Such high levels of efficacy reported in over 65 year olds surpasses all expectations we had for the first generation of COVID-19 vaccines. This group is amongst those most at risk of serious illness, and alongside healthcare workers must be prioritised to receive the first doses of any vaccines. It is critically important that regulators can now independently and rigorously assess the data.

“However, we must continue with efforts to ensure development, scale-up and fair access globally of a wide range of vaccine candidates. Ending this pandemic will take extraordinary levels of global collaboration, but through a combination of vaccines to protect those most at risk, effective treatments, tests and essential public health measures, we can overcome COVID-19.”


Dr Penny Ward, Visiting Professor in Pharmaceutical Medicine at King’s College London and Chair of the Education and Standards Committee of the Faculty of Pharmaceutical Medicine, said:

“This data confirms and extends the information available for the Pfizer BioNTech vaccine. More information is provided on the split of cases between the unvaccinated and vaccinated populations and on the occurrence of severe disease in each group.

“The vaccine is clearly effective at reducing the frequency of disease of all grades of severity, although there is no comment on hospitalisation/mortality noted. The incidence of severe disease among the cases of COVID reported was 9/162 (~5.6%) in the unvaccinated population compared to 1/8 (12.5%) in the vaccinated population. However, as 8 of the severe cases occurred in the unvaccinated population and only 1 in the vaccinated population, efficacy in preventing severe disease per se is still ~90% overall.

“More information on the split of higher risk individuals recruited into the trial was supplied, but the nature and pattern of disease in these subgroups is awaited and is necessary to interpret the reasons for the one severe case noted in the vaccinated population.

“More information is also provided on adverse effects. No serious events were reported. Grade 3 adverse effects (i.e. bad enough to interfere with usual activities) were reported after the second injection – fatigue in 3.8% (about 1 in every 25 people vaccinated) and headache in 2.2% (or about 1 in every 50 persons vaccinated). These can be expected to wear off within one or two days based on similar reports from other (non-COVID) vaccines; headache and other aches and pains usually respond to paracetamol or ibuprofen.

“This data continues to support the use of vaccination to reduce COVID morbidity in the population: full publication of the data is eagerly awaited.”


Prof Stephen Evans, Professor of Pharmacoepidemiology, London School of Hygiene & Tropical Medicine, said:

“This announcement in a press release is very good news indeed. There are now rather more data accrued with, it is said, no serious side effects.

“The numbers of cases of confirmed (but mainly mild) cases of COVID-19 split on the vaccine to 162 on placebo. From the previous press release it could be calculated that the split when there were 94 cases was 8:86. This suggests that in the more recent data, all the extra 76 cases were in the placebo group. This is slightly surprising and a highly significant difference in the later data. We do not know the reason for this.

“The statistical lower bound on the efficacy is now about 90% with the current estimate of about 95%. There is still statistical uncertainty in these data and any suggestions that 95% is importantly different from 90% or 94% should be ignored.

“It seems there is some evidence that in older adults (but we do not have data in detail and there are probably no data for 80 years and older) there is also very good efficacy with minimal side effects. This is again very good news, not just for this vaccine, but as it also makes it more likely that other vaccines will also be reasonably effective in older adults.

“There is also good news that severe COVID-19 is reduced as well as mild disease. Again, there is considerable uncertainty because results are based on only ten cases, but this is nevertheless good evidence that the vaccine protects against severe disease. Differences between vaccines cannot be concluded on the basis of these results.

“While we await a full paper, the FDA will have access to much more data and details than in a published paper. The head of the Biologics Center at the FDA, responsible for vaccines, has assured us that no politically appointed people are present for the assessment of any vaccines – they are briefed but do not attend the relevant meetings.

“If the data are also submitted to the European Medicines Agency, then we can expect both agencies to conduct a very careful evaluation and we can rely on their conclusions. Relying on a press release is not enough.”


Prof Trudie Lang, Director, The Global Health Network, Nuffield Department of Medicine, University of Oxford, said:

“Today’s update from Pfizer provides further encouraging news and more detail on the protection against disease that their vaccine is showing from this definitive phase III trial. The detail on achieving 94% protection in the elderly participants in the trial is particularly excellent news.

“The company are reporting that they now have enough efficacy data to submit for approval from the regulatory authorities, who will undertake a detailed assessment of both the efficacy and safety data. We will need to wait and learn over time how long the protection lasts, and to see whether this vaccine can also prevent transmission – meanwhile, this vaccine does look likely to have a strong role immediately once it is approved in protecting health workers and the vulnerable from disease.

“Another encouraging detail from this update was that of those cases that were considered severe, 90% of these had been vaccinated with a placebo. This ability to mitigate severe disease was a key question and so it is impressive that over 90% efficacy appears to be being maintained across ages and severity of disease. The safety data also looks very reassuring.

“This is a remarkable and very reassuring situation that we find ourselves in. To go from identifying a new virus to having several vaccines at the point of applying for regulatory approval is an incredible milestone for science.

“Having worked on vaccine development in several diseases such as Malaria, TB and Ebola, I am really encouraged. The progress here, the faster ways of working and the new technologies developed can be taken forward into other vaccine programmes and benefit other diseases. The achievements here have been supported by strong global collaborations and taking forward lessons learnt previously from other vaccine development programmes. Now ensuring there is equitable distribution and implementation across the globe should be everyone’s focus, alongside working within and from communities everywhere to build trust in these vaccines.”



All our previous output on this subject can be seen at this weblink:



Declared interests

Dr Penny Ward: “No COIs. I am semi-retired, but I am owner/Director of PWG Consulting (Biopharma) Ltd a consulting firm advising companies on drug and device development. Until July 2019 I was Chief Medical Officer of Virion Biotherapeutics, which was a company developing broad spectrum RNA therapy for the treatment/prevention of respiratory virus infections. Between December 2016 and July 2019 I served as Chief Medical Officer of Virion Biotherapeutics Ltd, a company developing antiviral treatments for respiratory viral diseases. Previous employee of Roche, makers of tocilizumab (anti IL6 antibody) and CMO of Novimmune, makers of empalumab (anti IFN gamma antibody).”

Prof Stephen Evans: “No conflicts of interest. I am funded (one day per week) by LSHTM. They get funding from various companies, including Astra Zeneca and GSK but I am not funded by them, I have no involvement in obtaining funding from them and I am not an investigator on any grants obtained from them. I am the statistician to the ‘meta-Data Safety and Monitoring Board’ for CEPI. I am paid for my attendance at those meetings and will be paid expenses for travel if that occurs.”

Prof Trudie Lang: “No conflicts of interest.”

None others received.

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