Top Rank outlined a double positive test for coronavirus on Monday as questions on Tommy Morrison were once again raised.
The incident happened ahead of their latest event taking place on Tuesday evening at the MGM Grand.
Jamel Herring, who was originally cleared of having COVID-19 after beating the virus, was one of those flagged.
The second was Luiz Melendez.
Revealing the disappointing situation, Top Rank said: “The Top Rank on ESPN main event between WBO junior lightweight champion Jamel Herring and Jonathan Oquendo will not proceed as scheduled after Herring tested positive for COVID-19 earlier this morning.
“The highly anticipated Mikaela Mayer-Helen Joseph junior lightweight bout will be Tuesday’s main event (ESPN & ESPN Deportes, 9 p.m. ET).
Said Herring, “I’m extremely disappointed that I’m not going to be able to fight tomorrow night.
“As I’ve shared previously, I tested positive for COVID-19 on June 22 after exhibiting symptoms. I quarantined and recovered as directed by my doctor.
“I then retested on July 3 and my test was negative. So this result is a complete surprise. I was fully prepared to make my second title defense tomorrow night.
I’m hoping that my team and Top Rank can reschedule this fight soon. Thank you for all the support everyone has shown. I can’t wait to get back in the ring and perform.”
They added: “In addition, the Luis Melendez-Eddie Vazquez bout has been canceled due to Melendez testing positive for COVID-19.”
In a shocking twist, Herring later confirmed he then tested negative for the standard range of the virus but has the antibodies to fight off further infection – for now.
“The moment I leave the MGM Grand, my antibody test results come back. I can’t win!
“It’s good to at least know I have the antibody in my system, that helps fight the virus now,” stated Herring.
The current super-featherweight ruler could now potentially fight again in the next few weeks.
Tommy Morrison’s wife Trisha has been warning of the dangers of false positives for some time now.
The widow of the late, great heavyweight champion gave her reaction to the news on social media.
Trish believes Tommy Morrison was a victim of such circumstances when accused of having HIV during the 1990s.
Upon his untimely death in 2013, ‘The Duke’ had no signs of the disease despite a two-decade fight to clear his name.