MEDIA outlets are increasingly reporting on vaccine progress, and in many ways, the month of December is looking more hopeful than ever.
However, the influx of hopeful news can also mean that it is hard to keep track of all the different vaccines and vaccine candidates, as well as of the different stages in their development.
In this special batch of Hope Behind the Headlines, we pick out the most salient developments that have occurred in the last month, focusing on three vaccines that have been approved or are near approval, and dig a little deeper into the data that are available.
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The pharmaceutical company AstraZeneca have worked with Oxford University to develop the so-called Oxford vaccine. The team have just published an interim analysis of some of their clinical trials in The Lancet.
Before the publication of the results, a preliminary analysis of phase 3 trial data hailed this vaccine as having an efficacy of 70% on November 23, 2020.
This means that the participants who took the vaccine were 70% less likely to develop Covid-19 than participants in the placebo group. This data were based on a trial that had included over 11,000 participants, 131 of whom developed Covid-19.
Although this 70% number made the headlines at the time, a deeper dig into the data since then revealed some puzzling inconsistencies.
When the scientists administered to the participants two full doses at least 1 month apart, the efficacy was 62%. However, when the participants received only half a dose the first time around (due to an error made by the experimenters) and the full amount in the second dose at least 1 month later, the efficacy jumped to 90%. Therefore, the 70% figure came from an averaging of these two end points.
These findings can be interpreted in two ways simultaneously. On the one hand, 90% is an excellent result, and knowing what dosage regimen is more likely to yield peak effectiveness is crucial. On the other hand, 62% efficacy at two full doses is “not that impressive,” as some experts have pointed out. While researchers do not yet know what may explain these differences in efficacy, experts have speculated on several potential reasons.
One reason could be the insufficient number of participants. There were not enough participants and therefore data to capture and account for the differences between the two dosing regimens.
