Preston is an idiot.
Shortage usually means reduced supply to a manufacturer. So in asking a manufacturer is there a shortage? The manufacturer will say no, because they are making as much, maybe more than they were before CV.
But to a buyer, a shortage means that demand has outstripped supply. So Gove was correct in that from a buyers perspective there is a shortage of reagents due to higher demand.
It’s exactly like online delivery slots....more groceries are being bought online than ever before. The supply of delivety slots have gone up, not down as they would if there were a shortage.
But to consumers, the buyers, there is a shortage because now the demand for online delivery slots is 10x higher.
Preston obviously didn’t ask the right questions.