In the period of hospital admissions shown by Kuipers, mid-November to mid-January, relatively few adults had received their booster shot. Then it is logical that a relatively low number (1.5 percent) end up in hospital. It is plausible that a higher percentage of boosted people now end up in hospital.
For a comparison between vaccination and hospital admissions, it is better to look at the booster vaccination rate in the middle of that period, in early December. At that time, roughly 5 percent of adults had been boosted. The booster still had a favorable effect, because 1.5 percent of the people in the hospital during that period had had the extra shot. But the booster rate of 5 percent is a factor of 10 smaller than the 55 percent that Kuipers showed on Tuesday evening.
The effect of vaccination without a booster also remains clearly favorable. The chance for unvaccinated people to end up in hospital is correctly represented in Kuipers’ picture. While only 14 percent of over 18s are unvaccinated, over 55 percent of adults in hospital are unvaccinated.