south korea
Excess mortality data from Europe, Israel, Singapore and Australia suggest that vaccine effectiveness against death has been overestimated. In Europe and Israel, post-vaccination waves were sometimes as or more deadly than pre-vaccination waves. And countries like Singapore and Australia saw sizeable upticks in excess mortality even after vaccinating a very large percentage of the population.

So while the vaccines do offer protection against serious illness and death, their effectiveness is unlikely to be as high as 90%.

Another interesting country to look at in this regard is South Korea. After containing the virus for the first two years of the pandemic, the country experienced a major outbreak in February of this year. By that point, Korea had double vaccinated 86% of its population, and around 90% of over 80s.

Like Singapore, Korea has one of the world's highest vaccination rates. At the end of 2021, 83% of Koreans were double vaccinated, compared to only 70% of Britons and only 63% of Americans (see chart below).
covid protocol graph
If vaccine effectiveness against death is as high as 90%, you would not have expected to see a large rise in excess mortality when Korea's outbreak hit. However, there was a large rise. By the end of March, mortality was 67% higher than normal (see below). This is a greater increase than France saw during the spring of 2020!
excess mortality graph
On the other hand, if we compare South Korea with Hong Kong - where more than half of over 80s chose not to get vaccinated - we see that excess mortality was even higher (see below). This suggests that while vaccine effectiveness may not be as high as 90%, it is greater than zero. Note that South Korea versus Hong Kong provides a useful comparison, since both are in East Asia, neither had a previous wave, and both got hit at the same time (with the same variant).
excess mortality graph
Excess mortality data from around the world suggest that vaccine effectiveness has been overestimated. Even countries that achieved very high vaccination rates before the virus got a foothold saw mortality jump once the virus started spreading.