England manager Gareth Southgate says online abuse he received after encouraging people to have coronavirus vaccinations “makes you think twice about speaking out”.
Southgate was targeted after presenting an NHS video following Euro 2020.
And he said he understands why players may not want to speak about having the vaccine.
“I recognise that others might feel less comfortable and have some anxiety,” he said.
“That’s why it’s a bit more complicated and I guess that would be why perhaps they might feel less confident about speaking up.
“If you’re receiving messages when you support the programme that say ‘You could be up in front of a Nuremberg-type trial in 10 years’ and people are quite vicious with comments, it does make you think twice about speaking out.
“Because what if you are on the wrong side? At the moment I couldn’t be sure I am on the right side. I am comfortable that I’ve had the vaccine.
“I’m comfortable that I think it was the right thing to do a video for the NHS. But I also recognise that others might not be so keen to put themselves in that situation.”
‘Conspiracy theories’ could be preventing young people getting jab
Southgate says he is unsure how many of his current England squad have received both doses.
Fewer than half of players at most Premier League and English Football League clubs have been vaccinated and earlier this week Republic of Ireland and West Brom forward Callum Robinson said he had not been vaccinated – despite having had Covid-19 twice.
Most England players have declined to talk about their vaccination status when speaking to the media this week.
Premier League managers have previously called on their players to get immunised, including Jurgen Klopp, Pep Guardiola, Mikel Arteta, Nuno Espirito Santo, Steve Bruce and Graham Potter.
“At their age they are more open to some of these conspiracy theories,” Southgate said of younger people in the UK.
“They are reading social media more, they are perhaps more vulnerable to those sort of views.
“From what I can see there is a bit of confusion around.”
England play Andorra away on Saturday in a World Cup qualifier before hosting Hungary on Tuesday. Back-to-back wins could see the beaten finalists from Euro 2020 secure a place at next year’s World Cup in Qatar, which will be held from 21 November to 18 December.
“I’ll always speak to the players about anything in their lives. But we are here to win football matches first and foremost,” Southgate added.
“Look, everybody knows where I stand on the subject. To move out of a pandemic, the only way was a vaccination programme and I think that was essential.”