COVID vaccine efficacy


The public policy response to COVID19 in most countries includes these two axioms – 1) mass vaccination is essential to end the pandemic, and 2) the vaccines do not prevent the transmission of the virus but they do result in a substantially lower seriousness of the illness in those that catch it.

So it is useful to interrogate these axioms by checking the actual data.

Here is how a small sample of countries is doing with vaccinations.

Israel did remarkably well to get above 50% over 6 months ago. Canada lagged but its vaccine roll out was then rapid. The UK and US are broadly similar. From this chart, the narrative would have you believe that the number of new COVID cases this year should have been highest in Canada, lowest in Israel with the UK and US in between. (Ignore Australia – there is insufficient data yet and it being a closed island creates a mismatch in comparisons to other countries; but I’ll leave the data as a sidenote.)

Here is the chart of new cases:

This chart shows the actual result to be opposite to the expected. Israel is suffering the most new cases, Canada the least and the UK, US in between.

What about the reduction in seriousness of the illness? Here is the case fatality rate:

Israel’s case fatality rate (CFR) has been very stable, showing some reduction this month. There is no obvious associated reduction in CFR with rising vaccination penetration.

Canada’s CFR dropped rapidly during the first half of this year while the vaccine penetration was only around 5% of the population. As the vaccine penetration rapidly increased, the CFR remained stable, with some reduction emerging just recently.

The CFR in the US is similar in pattern to Israel. The UK has seen a reduction in CFR in the last three months which roughly coincides with its increase in case numbers. Overall, the proposition that illness severity is reduced is not compelling.

There is enough evidence to conclude that mass vaccination is not going to end the pandemic. What is missing in this analysis is the effect of naturally acquired immunity relative to vaccine induced immunity. Could it be that a rapid vaccine rollout put a ceiling on natural immunity arising from cases of acquired COVID? I think that would be plausible. If so, an explanation for the actual data is that naturally acquired immunity is more effective than vaccine induced immunity.

One thought on “COVID vaccine efficacy

  1. “There is enough evidence to conclude that mass vaccination is not going to end the pandemic. ”
    That is as plain as day.
    ” What is missing in this analysis is the effect of naturally acquired immunity relative to vaccine induced immunity”
    Here’s an idea, “Let’s consider therapeutics some people don’t have to be hospitalized.”
    Unfortunately, Masks and vaccines are the only allowable considerations

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