"Hopefully we can get him tomorrow. We'd like to, but we'll see what happens," interim head coach Leslie Frazier said. "It's migraine-related. He's having some episodes, so we've just got to see how things go."
Harvin has dealt with migraine headaches since he was a teenager and missed several practices and one game last year, as well practices earlier this season with complications. He collapsed on the Vikings practice field on Aug. 19 and was taken to the hospital in an ambulance, but that episode was caused by a reaction to medication for the headaches, not a migraine itself.
He 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 seems to have decreased the frequency and longevity of the episodes since.
Several other Vikings who were held out of practice Wednesday remained inactive on Thursday, including DE Ray Edwards (ankle), G Steve Hutchinson (thumb), WR Greg Lewis (concussion), RB Adrian Peterson (ankle), and CB Chris Cook (knee).
Hutchinson, Peterson and Edwards might have a shot at practicing tomorrow, but Edwards could be the long shot of the group.
"That's the plan to try to get each one of them out here tomorrow, just see what they can do if they can go. Hopefully they can because we'd like to get a gauge as to how far away they are," Frazier said. "We'll see what happens tomorrow."
Hutchinson received a new cast over his thumb on Wednesday and did some work on the side Thursday to test his capabilities. Frazier said he talked to offensive line coach Pat Morris about offensive linemen who have played without the use of a hand.
"He's actually had a center who was a right-handed center who broke his hand and ended up snapping with his left hand," said Frazier, who couldn't recall the center's name. "That blew me away to hear that, but I guess you can do it. We'll see. We'll see where he is."
WR Sidney Rice (hip) was given the day off for precautionary reasons, like he was last week.
"Just try to get him to Sunday like we did a week ago. It should help him," Frazier said.
The Vikings also had a few players that were limited, including QB Brett Favre (ankle/neck/shoulder), who returned after being given Wednesday off. Safeties Husain Abdullah (ankle) and Jamarca Sanford (hamstring) were also limited.
Frazier, who has one game under his belt as an NFL head coach, could end up with a lot of game-day decisions.
"Yeah, it looks that way. It's not ideal," he said. "You'd like to know today who your starting lineup's going to be. It's that time of the year."
Wide receiver Bernard Berrian (groin) and safety Eric Frampton (hamstring) practiced fully for the second straight day.
For the Bills, G Eric Wood (ankle), CB Terrence McGee (knee), DE Dwan Edwards (hamstring), LB Reggie Torbor (shoulder), TE Shawn Nelson (illness) and NT Torrell Troup (fibula) were all held out of practice for a second straight day.
T Demetrius Bell (knee) and LB Chris Kelsay (illness) returned to practice on a limited basis while RB C.J. Spiller and DE Spencer Johnson (hamstrings for both) remained limited.
REPORT: BIENIEMY BEING HIRED BY COLORADO
Vikings running backs coach Eric Bieniemy will be the new offensive coordinator for the University of Colorado, according to the Denver Post. According to the Post, Colorado has decided on Redskins tight ends coach Jon Embree as its next head coach and Bieniemy is slated to be Embree's offensive coordinator.
Bieniemy declined to comment through a team spokesman.
Vikings interim head coach Leslie Frazier said he didn't have any update on Bieniemy about an hour before the Post broke the news, but former Vikings head coach Brad Childress, who brought Bieniemy to the Vikings, said before his dismissal that he had a lot of respect for Bieniemy.
"I do think highly of him. I think he can be a coordinator in this league and I think before it's over that he could probably be a head coach in this league," Childress said when asked about Bieniemy in relation to the Colorado job on Nov. 19. "I know what his recruiting skills are like. He's an excellent recruiter, excellent people person. Great, great teacher of offensive football. We'd hate to lose him, but certainly if he has that opportunity it would be hard to hold him back."
Tim Yotter is the publisher of Viking Update. Follow Viking Update on Twitter and discuss this topic on our message boards. To become a subscriber to the Viking Update web site or magazine, click here.