US Open ATP semi-finalists refuse to speak on COVID-19 vaccine, Djokovic, Medvedev and Zverev expressed doubts about it
The vaccination status of tennis players has been an ongoing issue for several years as several high profile athletes publicly expressed doubts over the safety of the vaccine. The ATP and WTA have encouraged their athletes to get vaccinated but so far numbers have been rather low (about 50 % among both men and women). The final four players standing at the US Open have not publicly spoken about their vaccination status but it's highly unlikely they have been vaccinated.
Novak Djokovic had COVID-19 last year and thankfully recovered but his stance on vaccines is rather well known. He famously said:
"Personally I'm opposed to vaccination, and I wouldn't want to be forced by someone to take a vaccine in order to be able to travel." He also expressed hope that vaccination will not become mandated which so far it hasn't been. Number two Daniil Medvedev also had COVID-19 and also recovered but he also expressed his intention of not getting vaccinated. He said:
"As for me personally, I will not be vaccinated for medical reasons related to vaccines."
Alexander Zverev took a softer stance on vaccination not saying he was for it or against it but expressed his belief that the issue has become too political. He said:
"Everyone should act as they see fit. Nowadays it's easy to be misunderstood, whatever you say. It's too political for my taste."
Felix Auger-Aliassime also publicly did not disclose his vaccination status but the Canadian never spoke about the vaccine either so it's hard to know for sure. The ATP and WTA so far are not making vaccines mandated and it's widely expected to remain that way. Players who don't get vaccinated will undergo mandatory quarantine ahead of the Australian Open as opposed to vaccinated players.