But as I said, these are not comparable quantities. 99.9% is the percentage of previously-infected people in Israel who were re-infected. This 99% is the perce

But as I said, these are not comparable quantities. 99.9% is the percentage of previously-infected people in Israel who were re-infected. This 99% is the percentage of infections which are reinfections. It's a totally different number. If we were to naively calculate an "effectiveness" from this data point (which I absolutely do not think we should do), it'd go like this: First, about 10% of the UK population has been infected. If there were no protection for re-infected people, we'd, of course, expect 10% of cases to be re-infections. Instead it's more like 1%, which suggests that being previously infected makes you 10x less likely to be infected. This gives a 90% back-of-the-envelope "effectiveness" against reinfection. Now, I don't think it's actually 90% - I think that analysis leaves out a lot of other information we'd need to know. And besides, we'd have to perform a similar conversion for the Israeli 99.9% number to have something to compare to. But we shouldn't make the mistake of saying "99.9% and 99% are in the same ballpark".