Here’s a recent graph from Maccabi Healthcare Services, one of the 4 Israeli HMOs, on the trajectory of their first 50,000 clients vaccinated. The green line represents 50,777 members who were age 60+ and vaccinated on December 19-24 (green line) versus Maccabi’s entire clientele of 480,000 age 60+ clients, including the 50k vaccinated (blue line).
The horizontal axis is days after the patient’s first dose. The vertical axis represents percent infected (blue and green lines) or percent hospitalized for COVID among the inoculated (yellow line).
So, the Pfizer vaccine doesn’t do anything for a couple of weeks after the first dose, but then kicks in on Day 14. By the end of the 3rd week, which is when people are supposed to go back for their second dose, it’s about 60% effective. And that’s probably understated because the blue line is 11% made-up of people in the green line, plus over time the blue line includes more and more people who were inoculated after December 24 and are entering the third week when the vaccine starts to work.
So this isn’t quite as good as in the Pfizer clinical trial. I believe they reported 89% efficacy from one dose by the end of three weeks, but their clinical trial sample wasn’t skewed as old as this one. But, it’s pretty good. It should make the Brits feel better about their controversial First Doses First strategy.
Another Israeli HMO called Clalit reported 33% efficacy from Day 14 thru Day 17. But in the Maccabi graph, efficacy steadily improves through Day 22, then flattens somewhat in Day 23, which is a different metric than what Clalit reported. So the two results might well be reconcilable.
So some takeaways from the Maccabi numbers: