Mead, who was named Euro 2022 Player of the Tournament, suffered an ACL injury when playing for Arsenal in December. Wiegman had previously said it would take a "miracle" for her to recover in time for this summer's tournament in Australia and New Zealand.
"I haven't told her she will be the captain -- that is how we have been all the time," Wiegman told a news conference. "We have just talked about football. She was selected and where she is at right now. We haven't really spoken about that yet."
Forward Beth England is also named in the squad after impressing for Tottenham this season following her Women's Super League-record move from Chelsea last summer.
"She is really close, she will train with the team. That was a hard call, like all the defenders we had to think about and she didn't get there with the 23," Wiegman said when asked about Le Tissier.
"We also see her more as a right back, at club she plays as a centre back, she has had a very good season but this is the choice we made."
England are looking to add to their trophy haul under Wiegman after winning last summer's Euro 2022 and the inaugural Women's Finalissima in April.
Wiegman also said it was disappointing that the women were limited to 23-player squads, while the men had 26 for their World Cup in Qatar last year.
"We wanted to bring it to 26," Wiegman added. "I don't think having 26 makes the injury risk lower, [but] I think you then have more options when something happens and you can keep someone in the squad and give more rest.
"The congested schedule, we all know when we move forward we have to do a better job all together to make it better in all stages and get better scheduling for the players."
The Women's World Cup begins on July 20, with England beginning their tournament against Group D opponents Haiti on July 22. They then face Denmark on July 28 and China on Aug. 1 in their final group stage games.
The final is scheduled for Aug. 20 in Sydney.
Full 23-player England squad
Goalkeepers: Mary Earps (Manchester United), Hannah Hampton (Aston Villa), Ellie Roebuck (Manchester City).
Defenders: Millie Bright (Chelsea), Lucy Bronze (Barcelona), Jess Carter (Chelsea), Niamh Charles (Chelsea), Alex Greenwood (Manchester City), Esme Morgan (Manchester City), Lotte Wubben-Moy (Arsenal).
Midfielders: Laura Coombs (Manchester City), Jordan Nobbs (Aston Villa), Georgia Stanway (Bayern Munich), Ella Toone (Manchester United), Keira Walsh (Barcelona) Katie Zelem (Manchester united).
Forwards: Rachel Daly (Aston Villa), Bethany England (Tottenham Hotspur), Lauren Hemp (Manchester City), Lauren James (Chelsea), Chloe Kelly (Manchester City), Alessia Russo (Manchester United), Katie Robinson (Brighton & Hove Albion).
Standby: Emily Ramsey (Everton), Maya Le Tissier (Manchester United) and Jessica Park (Everton).