Scientists say Pfizer’s announcement that its coronavirus vaccine is over 90 percent effective should be treated with caution. The news was made public through a press release and no data has been provided to support the company’s claims, which raises questions about how effective it might actually be in the general public.
The vaccine developed by Pfizer and BioNTech was widely touted as one of the most promising candidates against COVID-19. Pfizer initiated a Phase 3 clinical trial of the vaccine known as BNT162b2 on July 27. To date, more than 43,500 individuals have been enrolled in the study, of which nearly 39,000 have received two doses of the vaccine.
In the press release, Pfizer announced that it will continue enrolling participants until the “final analysis”, i.e., until 164 COVID-19 cases are confirmed in the cohort. To date, 94 cases have been confirmed.
“Case sharing between vaccinated individuals and those who received the placebo shows a vaccine efficacy rate of over 90 percent seven days after the second dose,” Pfizer stated. This means that protection is achieved 28 days after the start of vaccination, which consists of a two-dose program. As the study progresses, the final percentage of vaccine efficacy may vary”.
The company announced that it plans to work with BioNTech to submit data for review in a scientific publication once the full study is completed. It is not known when this will happen.
Pfizer said it expects to produce up to 50 million doses of the vaccine by the end of the year, and 1.3 billion doses in 2021, but both experts and politicians urged caution in the announcement.
President-elect Joe Biden issued a statement saying that while the results were “excellent news” and “cause for hope,” the fight against the coronavirus was far from over. “It will be many months before there is widespread vaccination in this country,” he said.
Scientists said the news from Pfizer and BioNTech was very welcome, but there is currently no evidence to support claims of 90% efficacy.
“The full data set on which the claim is based has not yet been published, so we do not know exactly what has been found,” said Eleanor Riley, Professor of Immunology and Infectious Diseases at the University of Edinburgh in the UK, in a statement.
“The two companies are trying to point out that the study participants are ethnically different, which is good, but they do not say anything about the age of the study participants. If a vaccine is to reduce serious illness and deaths and thus enable the general population to return to normal everyday life, it must be effective in older and elderly members of our society. We also do not yet know the severity of cases observed in the study, whether infection or infectivity has been prevented or how long immunity is expected to last”.
Michael Head, Senior Research Fellow in Global Health at the University of Southampton, UK, also expressed concern about the results published in a press release and said that whether the vaccine is effective in the elderly will be key to its success – which is currently unclear.
It is known that older people are more likely to develop severe cases of COVID-19. In the USA, there are about 40 million people over the age of 65. If a vaccine is not effective in this group, its overall effectiveness is likely to decrease.
The vaccine has also not been tested on pregnant women or children.
Head said there would also be major problems in distributing the vaccine: “It has been reported that the vaccine has to be stored at minus 70 degrees Celsius, which is not necessarily routinely available in most health centers, even in the UK, let alone worldwide.
Others pointed out that, since two doses are required, the true effectiveness of the vaccine will only be known in time. The need for two doses will also have an impact on vaccine production – i.e. Pfizer’s claim of 50 million doses means that 25 million people have been vaccinated.
Another major hurdle in distributing a vaccine, even if it proves to be 90 percent effective, is getting people to take it. Surveys from the USA show that the willingness to take a vaccine against COVID