I have spent a good deal of the day reviewing the massive data dumps from the Pfizer trials and an event bigger dump in Lancet today from the Oxford group.
The Pfizer data is well presented and is clear. It is a highly effective vaccine. The length of the immunity is unknown. We know nothing of its ability to prevent asymptomatic spread. It is safe, although I think in press reports of the significant and unpleasant local effects and the transient systemic effects have been minimized. However, they were all in the nuisance category with no long term harm. This is clean data and comparatively easy to discern. As above, there are issues that the study did not address. The local reactions were anticipated prior to the study by the way, so they are no surprise.
The Moderna vaccine is similar, and I expect data to be similar and the side effects. The cold chain is much less arduous.
So we await the publication of their results.
The Oxford group published their results in The Lancet today. There is a lot of data here, and picking out the details takes time and some discernment.
The whole study is somewhat disorganized in many ways. However it does contain a lot of useful information.
The vaccine has been studied in the UK, Brazil and South Africa. However the South African data is incomplete.
It seems originally this vaccine was designed to be single dose. But early phase data showed a less then hoped for immune response. So the booster dose at a month was added. Now for various reasons early dosing was at half the dose it ended up being. So some early enrollees had a low first dose and a full second dose. Now the trial was designed to have the doses given 28 days apart. However because of early difficulties in manufacture, some enrollees got their second doses at 6 and 8 weeks after the first. This actually in the end produced some intriguing data. In addition the subjects in the Oxford study were more ethnically diverse than in the Pfizer study. The age ranges are similar in both studies. However the half first dose subjects were a significantly lower age group. However in the two full dose studies there really was no significant difference in effectiveness between age groups. So I tend to agree with professor Pollard that the increased effectiveness of the LD/SD regime is almost certainly real. So the vaccine was 60% effective in the SD/SD group and 90% effective in the LD/SD group. If you combine the groups then you get a 70% effective result.
Now because of the 6 to 8 week delay between doses you can infer that one dose is 50% effective. That would make it questionable to advise a single dose regimen. However there was no significant change in effectiveness when the second dose was delayed.
In addition this group did study asymptomatic and symptomatic PCR testing. Even one dose drastically reduced asymptomatic PCR positivity. This has enormous public health implications and is very positive news.
The other really encouraging thing is that as far as I can tell no subject who had at least one dose of either of these vaccines became seriously ill. All the serious illness and deaths were in the placebo arm.
In addition in both studies great care was taken to discern any evidence of vaccine acceleration. There was no evidence of vaccine acceleration even in those vaccinated who had previously had conformed Covid-19 infection. I think this vaccination of previously infected subjects was only addressed by the Oxford group.
There seems a bit of a dispute developing I think between Pfizer and the regulator. As far as I can discern, the FDA want the control group to remain unvaccinated to better understand the long term side effects. Pfizer feel, and I agree, that this is unethical and they plan to vaccinate subjects in the placebo arm.
So there is a lot of information to digest and I'm sure with experience, clinical practice and recommendations will evolve.