Pfizer says that a third shot boosts antibody levels 5x to 10x against COVID Classic and Beta. Remember that antibodies aren’t the whole story, and that Pfizer has incentive to get as many people as possible to buy their vax. They also said they are working on a Delta-specific booster.
This article argues that splitting vaccine doses (so there are more of them) would be a Good Thing.
This study shows that CoronaVac (which is used in many many places in the world) had an efficacy of 83.5%. Note, however, that they didn’t have any participants older than 59, there were very few cases over the period of the study, and it was probably too early to catch Delta cases.
Preliminary news from Cuba is that their three-dose regimen — two of Soberana02, one of SoberanaPlus — gives 91.2% efficacy.
This article says that 1.3M Canadians got a different second dose brand than they got for their first dose.
Note that there are at least four things that affect how sick you are going to get:
- Your genetics. For example, supertasters are less likely to be hospitalized.
- The amount of virus which you are exposed to. If you are exposed to trillions of virus particles, you are more likely to get sick than if you are exposed to one.
- How good your immune system is on that day. Your immune system will not be as effective if you are having a bad day. (I got a chronic sinus infection right after my mother died, and I don’t think it’s coincidence.)
- What antibodies your body comes up with. The immune system creates a bunch of different antibodies, basically at random, and tries them to see what fits. It makes more of the ones which work better, but it might only come up with one that’s 50% as effective as one that your neighbour comes up. This is just blind luck, as far as I can tell.
This study found that the speed of the innate immune system responding to SARS-CoV-2 was important, and that if people already had high levels of innate immune system activation due to an RSV infection (one of the many “common cold” germs), then that completely inhibited SARS-CoV-2.
This article reports on a study which found that proxalutamide, an experimental prostate cancer drug, reduced COVID deaths by an amazing 77%. This would be great, but take a giant boulder of salt for the moment: there are a lot of scientists looking askance at the paper for various reasons. Still, it would be great…