Bill Gates, long recognized as one of the world’s foremost proponents of vaccines, raised some eyebrows at a recent talk in Australia when he admitted there are “problems” with current COVID-19 vaccines.

Speaking at Australia’s Lowy Institute as part of a talk entitled “Preparing for Global Challenges: In Conversation with Bill Gates,” the Microsoft founder made the following admission:

“We also need to fix the three problems of [COVID-19] vaccines. The current vaccines are not infection-blocking. They’re not broad, so when new variants come up you lose protection, and they have very short duration, particularly in the people who matter, which are old people.”

Such statements came as a surprise to some in light of Gates’ longstanding support of — and investments in — vaccine manufacturers and organizations promoting global vaccination. However, they were the latest in a string of developments in recent weeks that have increasingly called the COVID-19 vaccines, in particular, into question.