Vaccines new and very new

First, two new vaccines.  Johnson & Johnson and Novavax put out press releases about their vaccines last week. These are two vaccines that NZ has agreements to buy.  The Novavax vaccine is (a slightly modified version of) the viral spike protein. The mRNA vaccines (Moderna, Pfizer) get your body to make this protein, and the DNA vaccines (AstraZeneca, J&J) get your body to make mRNA to make the protein; a protein vaccine cuts out the middleman.   Novavax are reporting good results, estimating 95% efficacy against the original variants of SARS-2-CoV [?Covid Classic], about 85% against the B 1.1.7 (“UK” variant) and about 60% against the B 1.351 (“South Africa” variant). That’s as good as the mRNA vaccines against the original strains. It might well be as good against the new variants — we don’t have direct randomised trial estimates of effectiveness for the new variants and the mRNA vaccines, but we have antibody tests that suggest substantial but lower protection. Johnson & Johnson didn’t provide much data, and they aren’t claiming as high effectiveness, but they are claiming to prevent serious disease and death, and it’s a single-shot vaccine. We will presumably see more information from both companies when they are evaluated by the FDA and its European counterpart, as we did for earlier vaccines.

Next, the AstraZeneca vaccine in people over 65.  The situation has clarified a bit, though it’s still not clear what number Handelsblatt were quoting.  There is very little Covid data (so far) on people over 65, because there were very few in the trial.  This will improve somewhat when data are released from trials in India and the US.  There is good reason to expect that the vaccine would work in people over 65, but very little direct experience.  In a usual drug-approval situation there is a very strong status-quo bias: the status quo is often not that terrible; the drug doesn’t realistically promise a big improvement; you don’t want to give drug companies incentives to cut corners in trials. Usually it’s better to postpone a decision for a year or so to get better information. With Covid, the status quo is a massive human and economic disaster, and the balance of risks is very different. Leaving people unvaccinated is dangerous, epidemiologically and to the global economy as well as to them personally, so it’s not clear whether the ‘safe’ approach for regulators is to approve the vaccine for all ages or carve out an over-65 exception. It probably depends on the country.

Finally, arithmetic. Israel has been doing well at delivering vaccines, and we’re starting to see rates of infection after vaccination. These aren’t straightforwardly comparable with vaccine efficacy numbers.  A story in the Jerusalem Post has the headline Just 0.04% of Israelis caught COVID-19 after two shots of Pfizer vaccine  and goes on to say (emphasis added)

According to the studies conducted by Pfizer, the vaccine had an efficacy of about 95%, which is considered very high. The Israeli data appear to confirm the inoculation’s effectiveness, showing an even more promising result.Later in the day, Maccabi Healthcare Services – one of the country’s four health maintenance organizations – released the first results of the vaccination campaign of its members, with the organization also comparing the data to a control group that did not get inoculated.
Some 248,000 Maccabi members were already a week after the second shot as of Thursday. Of those, just 66 got infected with the virus, the majority of them over the age of 55 and about half of them with preexisting conditions. All those infected experienced only a mild form of the disease, and none were hospitalized.Over the same period of time, some 8,250 new cases of COVID-19 emerged in the control group of some 900,000 people having a diverse health profile. Those who were not inoculated were therefore 11 times more likely to get the disease than those who were immunized, showing 92% effectiveness.

95% effectiveness means you’d expect 5% of vaccinated people to test positive as infected if 100% of unvaccinated people did. Or 0.05% test positive as infected if 1% of unvaccinated people did. But 1% is a very high rate — the US, at its very worst, wasn’t getting close to 1% of the population as new cases in a week.