The only way this gets insider trading pinned on it is if the vaccine turns out to have issues and the stock price takes a big dive later. If the vaccine works, they sell tons of them and the stock price stays up, then there's no advantage gained by selling now. So, no insider trading. We will have to wait and see.

I suppose it could also be if this CEO had bought a ton of extra shares in anticipation of the food news dropping, but executives trades are publicly reported so we would have known about it.