Asked whether Chris Samba and David Dunn were two of the sufferers, Allardyce said: "It's definitely swine flu - you've speculated on the names and I'll leave it at that.
"We have had one more case this morning, one more player and there are a couple of staff.
"Other than that, the others that we left behind are recovering well but not available for tomorrow."
Allardyce said Blackburn had only decided to play the fixture at Stamford Bridge - which they lost 5-0 - because they were bound to do so by Premier League rules, and admitted there was a chance the virus could have been passed on.
"The Premier League has tried to sit on the fence by saying that we didn't request to have the game called off," Allardyce said.
"We knew we couldn't get the game called off because we were told way back in February or March when we took some guidelines that unless there was some government legislation, everybody had to do whatever they had to do.
"If there was a swine flu outbreak, you couldn't call a game off, no matter what.
"We fulfilled our total, 100 percent, responsibility by confirming two cases of swine flu and suggesting that it looks like one or two other players and members of staff had similar symptoms, and we made the same phone call to Chelsea."
Asked about the danger of it spreading on a match day, Allardyce said: "It's a highly contagious strain as everybody knows but I can't comment any further than that."
Blackburn 8/11, Draw 5/2, Peterborough 4/1