Martin Kulldorff develops new statistical and epidemiological methods for disease surveillance, many of which are relevant for cancer research.

Put another way, vaccinated individuals were 27 times more likely to get a symptomatic COVID infection than those with natural immunity from COVID.
Here's the full study:

Martin Kulldorff also insists vaccinating the young is a mistake.
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Sources
https://www.dfhcc.harvard.edu/insider/member-detail/member/martin-kulldorff-phd/
https://thehill.com/opinion/healthcare/558757-the-ill-advised-push-to-vaccinate-the-young
https://www.medrxiv.org/content/10.1101/2021.08.24.21262415v1