1) The low efficacy of the Novavax vaccine candidate against the B.1.351 is concerning. However, the data is also reassuring in many ways. First, the vaccine itself worked very well against the 'old' SARS-CoV-2 variants and the B.1.1.7 (UK) variant. Also, the vaccine...

2) ...seems to work almost as well in HIV positive individuals as in HIV negative individuals. And, vaccine efficacy against B.1.351 seemed markedly reduced, but still present. This was against symptomatic disease in general. It is very likely, that the efficacy against....

3)...severe disease is much higher. There are also some other things we can learn here. Novavax was reporting very high neutralization titers from their initial clinical phases, around 1:3500. Now, we see that there is a reduction in neutralization against B.1.351....

4)...of about 6-10-fold (depending on the preprint, for some even higher). That would result in a 1:350 neutralization titer. That's around the titers that Pfizer reported against the wild type strain. This could mean two things: The readouts of different neutralization assays...

5)...run in different labs are not comparable. Or, neutralizing antibodies are not the (only) correlate of protection. Or both. But it would be good if independent labs could run sera from several of the current vaccine trials and compare directly. Another important point is....

6)....and that it may be hard to extrapolate efficacy reduction from one vaccine to another. The Novavax data may indicate that the Pfizer and Moderna vaccines could also fall to 50% efficacy against some of these variants. Or the reduction could be much less...

7)....What also needs to be kept in mind is that the numbers are still small. Once numbers are accumulating, the picture may change a little. And let's not forget, 50% would not be great, but its MUCH better than nothing......

8)....especially if there is higher efficacy against severe disease. Let's wait for more data. And in the meantime, let's bring case numbers down.

9) PS: Since I was called pedantic today already on Twitter. It is Shabir Madhi, not Shabir Maddi. @Novavax https://ir.novavax.com/news-releases/news-release-details/novavax-covid-19-vaccine-demonstrates-893-efficacy-uk-phase-3

10) I take the comment about efficacy in HIV+ individuals back. Sloppy reading and misinterpretation of the data on my side. Thanks to the people who were making me aware. Apparently I am not pedantic enough.