MEMPHIS, Tenn. (NewsNation Now) — A Tennessee doctor has died of a COVID-related illness. He tested positive for COVID antibodies and had been recently vaccinated, but his doctors are speaking out that the vaccine did not contribute to his death.

Dr. J Barton Williams went from doctor to patient when he fell ill weeks ago. Dr. Stephen Threlkeld helped treat him at Baptist Hospital.

Threlkeld says the disease quickly went from diagnosis to death.

“It was matter of days,” Threlkeld said. “Just a tragedy.”

Williams, an orthopedic surgeon for OrthoSouth, died February 8 of multisystem inflammatory syndrome or MIS, a condition usually affecting children and attacking the immune system.

“The immune system attacks the body in many ways and causes multi-organ system failure,” Threlkeld said. “It affects the heart, the gastrointestinal tract and other places.”

Threlkeld says Williams tested positive for COVID-19 antibodies, meaning he had COVID at one time, but he never knew it. And he had gotten his second COVID-19 vaccine just weeks before his death.

After rumors that the vaccine contributed to his death, Williams’s family allowed those who treated him to do the unprecedented: speak out about his condition.

“The family has been incredibly generous and courageous in allowing the details of his case to be put out there for those of us who took care of him, just to try and make sure the facts were out there true,” Threlkeld said.

They want to dispel rumors this was a new variant of coronavirus. Threlkeld says they never found an active virus in Williams body.

“It does seem to be in every case we have seen so far, to be related to the virus itself,” Threlkeld said of MIS. “It’s a post-viral, sometimes a few weeks later, a post-viral effect. Not during the first part of it.”

We asked if the vaccine could not be a protector against this because Williams had already been predisposed to the coronavirus.

“It’s a very important question. All preliminary,” Threlkeld said. “We are working with the CDC to see how vaccines can play in all directions. We don’t have any data to suggest the vaccine has any effect in either direction.”

Health officials are meeting daily to study Williams’s rare case. But they’re still spreading the message that everyone should be vaccinated.

“The way to avoid this rare, albeit terrible, illness is to get the vaccine,” Threlkeld said. “The way to avoid it is to prevent the infection in the first place.”

He says it’s something Williams would want.

“He would want this out there and the facts. he would want the true facts out there and to have an effect to save other people,” Threlkeld said. “And you certainly hear his voice in this by saying get your vaccine.”

We’re told the exact cause of Williams’s death has not been determined and an autopsy is pending.