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Covid-19 vaccine breakthrough
By ECCT staff writers
A Covid-19 vaccine being developed by Pfizer of the United States and Germany’s BioNTech has been found to be more than 90% effective, according to new independent analysis. The breakthrough means that that the vaccine could be made available for use by the end of 2020 if drug authorities approve its use.
The finding was the result of the first independent analysis of any Covid-19 vaccine in phase 3 trials, the final stage before commercial licensing is granted. According to the analysis, out of the 43,3538 trial participants from diverse backgrounds, the small number of people who were infected (94) enabled the independent evaluators to calculate the effectiveness after two doses of the vaccine. In addition, no serious safety concerns have been observed to date (although data continues to be collected).
Progress on two more vaccines, from AstraZeneca, which is working with a team at Oxford University, and Moderna, an American biotechnology company, are also expected in the coming weeks. The AstraZeneca-Oxford vaccine is already known to stimulate a good immune response in the elderly. Even if Pfizer’s vaccine does not do so well in this group, therefore, there is a good chance that another will.
Questions about the vaccine remain. One is the extent to which it works in elderly people, one of the groups most vulnerable to Covid-19, and who may not respond as well. Another is whether it prevents infectiousness (it remains possible that a vaccine could prevent someone from getting the symptoms of covid-19, but not from spreading it to others). Moreover, it is not yet known how long one course of the vaccine will be effective.
There are also formidable production and distributional challenges ahead. Current projections suggest 50 million vaccine doses will be available in 2020, and 1.3 billion in 2021. Given the fact that two shots will be required for each person (injected three weeks apart), this means that, based on current projections, there will only be enough doses for fewer than 700 million people within a year, far short of the number projected to be needed to achieve global herd immunity. In the longer term, vaccine efficacies of 90% will make it feasible to generate herd immunity. If enough people take such an efficacious vaccine, then those who do not or cannot will also be protected. In the short term, though, the vaccine is likely to be used where most needed, such as for healthcare workers and the elderly.
Another challenge is that the world has never undertaken vaccination on such a large scale. Pfizer’s vaccine requires vaccine doses to be kept frozen until just before use, which poses a significant challenge for regions where electricity and transportation infrastructure is patchy.
Nevertheless, medical professionals say this breakthrough is a cause for celebration. The mRNA approach that Pfizer and BioNTech are using has never been shown to work in humans before. The data gathered from the trial mean the minor revisions to the mRNA sequence can be made, thus changing the proteins the body develops immunity to. This means that if new strains of Covid-19 emerge, different versions of the vaccine could be created to target the new strains.
