It is most perplexing then, that Sullivan, who is writing about the end of an epidemic, after all, never mentions the word vaccine in his article.
Sullivan was writing about the epidemic without talking about the vaccine.
Sullivan was writing about the epidemic and  the vaccine.
We might need a convention.
He was definitely correct.
A boater is swimming in the water next to their overturned boat.
A man is waiting for his luggage at the airport.
People are buying ice cream at the indoor market.
He said this just now.