It's 96% effective against the original covid strain, 86% effective against UK variant B.1.1.7, but only 49% effective against the South African variant B.1.351...

That 49% has two confounding factors, 1: it includes a significant portion of hiv positive individuals, the efficacy was 60% if you exclude them. 2: N is not large enough to give you reasonable confidence in either of those numbers the ci was between 19%-80%, which is almost useless, not quite, since it seems like there is evidence that it is at least a little less effective, but by how much is still anyone’s guess at this point.

> only 49% effective against the South African variant

The South African data is a much smaller study without much statistical power and with an extremely wide 95% confidence interval. I’d take that figure with a grain of salt. Kudos to Novavax for including it nonetheless.

Oh no! Better not give it to anyone!

I am not an expert, but I think I read that once you acquire immunity to a virus it might be more difficult to acquire same or better level of immunity to a similar virus.

That's why you can't take vaccine for all strains of influenza and if prediction of which strain is going to be prevalent is wrong and you take wrong vaccine you can't do much about it.

Now, the Covid-19 vaccines are different mechanism so I don't know if or how this translates. For now what I read about the way the mechanism is built on some of the vaccines is that these should really be effective even if there are large changes to the virus. But there are of course always specific mechanisms and sequences that the immune system requires to recognize and act on virus and so there can never be universal vaccine.

I think some robust citation is needed for this.

The concept in question is original antigenic sin [1], and is real, though it's unclear whether it applies to immunity in this case.

[1] - https://en.wikipedia.org/wiki/Original_antigenic_sin

That’s interesting, thank you for the reference.

This is not an accurate speculation.

They try to predict flu strains because it is prohibitive to identify and produce vaccines for every strain in time for flu season each year.

By your assertion, the entire notion of yearly flu shots would be irrelevant.

Smart smaller countries that can't get supplies should approve this now and have all the supply to themselves. Or maybe the EU can do that instead of trying to get the UK supply...

The linked article seems to say that even if the UK approved this vaccine today, we wouldn't get our doses until the second half of the year. I don't know if that's because earlier doses are earmarked, but it sounds like it's going to take time to get production up to speed.

Worth remembering these vaccines are even more successful at stopping death and hospitalisation, than the headline efficacy figures. The headline figures count any COVID as a failure.