Harvin missed all of last week except for a small portion of last Wednesday's practice, when the latest migraine initially took him out of commission. He wasn't at practice this Wednesday as the Vikings began preparations for the New York Giants, pushing his non-participation to more than a week long.
"He has a little bit of an illness. We'll monitor it and (athletic trainer) Eric Sugarman and the staff will let me know this afternoon, but he has an illness and I don't think we'll get him on the field," Frazier said.
"My understanding of the migraines is they can come and go, so we're just being precautionary with Percy as we're trying to get him ready and hopefully take care of some things that will help him long term. It will be day-to-day situation as to whether he's out here or whether he's not out here."
Harvin visited the Mayo Clinic in Rochester, Minn., last year to try to cure the migraines or minimize their effects, and a diagnosis of sleep apnea appeared to have decreased the frequency and longevity of the episodes since, but Sunday marked the second game in his two-year pro career that Harvin has missed because of the migraines. Frazier said the receiver wouldn't be going to the Mayo Clinic this week.
"We want to try to do whatever we can to ascertain whatever's the best thing for Percy so we're trying to do that," he said.
"He should be fine and he should be able to play on Sunday," Frazier added, noting, however, that he also said that last week.
In addition to Harvin, the Vikings had five other players that didn't practice Wednesday: Quarterback Brett Favre (chest/ankle/shoulder), defensive end Ray Edwards (ankle), cornerback Chris Cook (knee), safety Tyrell Johnson (knee) and quarterback Joe Webb (hamstring).
"Ray Edwards, he's improving. We're taking a look right now as to whether it would benefit him to try today or try tomorrow, but he is making improvements so we think there's a chance that we may have him this weekend," Frazier said before Wednesday's practice.
Four others were limited – running backs Adrian Peterson (ankle) and Toby Gerhart (hamstring), guard Steve Hutchinson (thumb) and receiver Sidney Rice (hip).
"I honestly feel like I'm getting better and better each week, so I'm interested to see what this week will be like," said Rice, who added that he was amazed that his leg got bent on one catch Sunday and he didn't feel pain.
"I seen on the replay how my leg came all the way up to my shoulder. I was surprised, but I didn't feel no pain and it didn't bother me after the game so I was happy about that."
Hutchinson didn't practice at all last week.
The Giants had only two players that didn't participate at all in practice – tackle Shawn Andrews (back) and running back Ahmad Bradshaw (wrist). Cornerback Will Blackmon (chest), safety Brian Jackson (hand), wide receiver Hakeem Nicks (lower leg), center Shaun O'Hara (foot), wide receiver Steve Smith (pectoral) and defensive end Osi Umenyiora (knee) were limited.
Running back Lorenzo Booker began practicing with the Vikings on Thursday after being officially signed Tuesday. The former third-round pick of the Miami Dolphins also spent a year with the Philadelphia Eagles and just finished a stint in the United Football League.
Frazier said Monday he was hopeful that Booker could make a contribution as a third-down back in the near future.
"One of the plusses in signing Lorenzo is that he was in a similar system in Philadelphia, so some of the terminology, some of the things we're asking him to do aren't unfamiliar to him," Frazier said. "We're hoping that as we go through this and we give him information there will be great recall and there's a possibility we may be able to get him on the field on Sunday. That's what we're hoping. We'll take it day-by-day."
"It's a potential solution to what we see right now as a potential problem," Frazier said of the lack of depth at quarterback. "We're optimistic as we mentioned before that Brett is going to be fine and Tarvaris will be good. With Joe's situation being what it is, we needed someone for practice. R.J. gives us that."