Vaccine Effectiveness and Excess Mortality in Singapore

In several previous posts, I’ve noted that excess mortality data from Europe and Israel suggests that vaccine effectiveness against death has been overestimated. For example, the chart below plots excess mortality over time in Israel:

The shaded area corresponds to the period of time by which more than 80 percent of over 60s were doubled vaccinated. Comparing it to the area that isn’t shaded, the overall level and pattern of excess mortality is almost identical.

In fact, if you showed someone the shaded and unshaded areas, and asked them to guess which one represents the pre-vaccine rollout period, and which one represents the post-vaccine rollout period, they wouldn’t be able to tell.

Now, this certainly doesn’t mean that vaccine effectiveness against death is zero. But it is hard to reconcile with claims of, say, 90% effectiveness against death. And excess mortality data from Singapore appears to tell the same story.

Singapore has one of the world’s highest vaccination rates, and the overwhelming majority of doses given were either Pfizer or Moderna. (In other words, only a small percentage of Singaporeans received the supposedly inferior Sinovac vaccine.)

In addition, the rollout was completed in good time, as the chart below indicates. By 31st August 2021, 78% of over 80s and 88% of those aged 60–79 had been double vaccinated.

However, these high vaccination numbers were not enough to prevent a substantial rise in excess mortality during the country’s Delta wave, as the chart below indicates.

Singapore successfully contained the virus until the autumn of 2020, by which time the country’s leaders had realised Zero Covid was not a viable long-term strategy. However, excess mortality reached more than 30% in both October and November – approximately the same level as in Germany.

Given the very small number of unvaccinated elderly people – by 1st October, around 84% of over 80s had received two vaccine doses – it’s difficult to square the excess mortality figures with claims of 90% vaccine effectiveness against death.

Having said that, the data from Singapore probably aren’t quite as unexpected as the data from Israel and Europe. Singapore hadn’t really seen any waves of Covid prior to the autumn of 2021, so there may have been more ‘dry tinder’ in the population when the Delta wave got underway.

Hong Kong is currently going through what looks to be a deadly Omicron wave, its deadliness apparently driven by the country’s low elderly vaccination rate. So even if vaccine effectiveness against death has been somewhat overstated, using the vaccines to help achieve focussed protection certainly makes sense.