Using a country that had not given out boosters, like the USA or UK until recently, you’d get a better idea of the efficacy of the vaccine against Delta infections.
Moreover even in Israel the daily cases among double vaccinated are less than those among the unvaccinated. Look at the chart here https://www.ft.com/content/a1b2fd70-71b5-4e91-be0b-553b0e1e2... The line for “Two dose” cases per 100k among over 60 year olds is below unvaccinated since august 15 and continually remains less.
90%? No, that’s too high, but for instance data from public health England is saying the vaccines have around 15-45% efficacy (or 40-80% if doses 8+ weeks apart) against covid-19 infection after 25+ weeks, not 0%. https://mobile.twitter.com/EricTopol/status/1437890711139995...
Looking at your link, it looks like the comparisons they make are purely based on COVID case counts and vaccination percentages. There are other factors that need to be considered: counties with higher vaccination rates in the USA are also likely to have a higher rate of testing, due to the politics of COVID (people who are more afraid of COVID are both more likely to be vaccinated and more likely to get a test when sick). At the country scale, it seems like something similar may be going on: they compare Portugal and Israel with the poorer countries of South Africa and Vietnam and state their case rates are similar. But different countries are using different policies which may affect the infection rate there. For instance, Vietnam has used lockdowns and border closures in recent months to slow the spread of the virus,[1] while Portugal with its high vaccination rates has recently removed almost all COVID restrictions.[2]
[0] https://www.cnbc.com/2021/08/25/covid-protection-for-the-ful...
[1] https://en.wikipedia.org/wiki/COVID-19_pandemic_in_Vietnam#M...
[2] https://www.reuters.com/world/europe/portugal-lift-most-rema...