Khamzat Chimaev seemingly has retired from his MMA career as he is still suffering from severe lingering effects of COVID-19."Borz" posted a picture on his Instagram detailing why he thinks his mixed martial arts days are over due to the physical effects caused by the disease.Before the retirement announcement, Khamzat Chimaev also uploaded a picture of him supposedly coughing up blood in a sink. This is what he wrote according to a translation from Russian:"Take yourself and your family. This is the most important thing. The main thing is I do not know what this disease is but it is not easily outlived," said ChimaevChimaev also posted the following in his Instagram Story about 25 minutes ago.Translated photo via Reddit courtesy of r/mma user u/thesalamandirk pic.twitter.com/swBAaI9AT3— Aaron Bronsteter (@aaronbronsteter) March 2, 2021Here are some of the best reactions on Twitter from MMA fans and Khamzat Chimaev's colleagues:No way. Obviously hope everything is ok with his health but super sad to see a guy with as much potential as he had not see it through against elite talent. I texted all my mma friends after watching his first fight in the ufc saying I thought he was a 185 khabib. Freaky good.— Big Ev (@DoubleVodkaDon) March 2, 2021Wow. If this is true he’s one of the biggest what if’s I can think of.— Jack McGuire (@JackMacCFB) March 2, 2021Is this only from covid? Didn’t ufc fly him to America for additional care.. is ufc saying he can’t continue with his athletic career? Crazy..— ztrain12 (@ztrain12) March 2, 2021Could have dethroned usman..— Abhijeet Singh (@abhijeetacm) March 2, 2021Maybe he makes a comeback a few years down the line when his body feels better. But good for him. Not forcing his way back. Hate to see such a great talent retire early but it’s for the best if he’s not healthy— Larry Freakgerald (@freakgerald) March 2, 2021Just here to wish Khamzat Chimaev all the best and hope he fully recovers.As a huge fan of the sport of course I hope we see him back in the Octagon. If he feels he can't do it anymore bc of health issues, we should respect that.— MaRCeL DoRFF 🇳🇱🇮🇩 (@BigMarcel24) March 2, 2021Khabib had a point in his career where he wanted to quit because of his back injuries, but his father convinced him to stay— Self Proclaimed MMA expert (@realUFCfighter) March 2, 2021So sad he’s one of my fighters I really hope he one day recovers n comes back it’s obvious covid problem and the long last dmg of the lungs he needs time to recover praying 🙏— Vetrix (@Hzmework) March 2, 2021inshallah he recovers 100% and decides to return he has so much potential 💔.— Hassan Ahmed 🦅 (@hassan__ahmed99) March 2, 2021Khamzat Chimaev's UFC careerUFC Fight Night: Chimaev v MeerschaertThe Swedish-Russian fighter impressed combat sports fans in 2020 when he debuted in UFC and followed to win two more bouts in Fight Island within an interval of just two months.Competing in the Welterweight division, Khamzat Chimaev quickly positioned himself as a title contender in the weight class. UFC booked him to fight Leon Edwards in December 2020, but the British fighter had to pull out of the fight as he contracted the virus.Edwards reportedly also experienced a severe case of the disease, losing 12 pounds while sick. The bout was rescheduled to January, but this time it was Khamzat Chimaev who tested positive for COVID-19."Borz" struggled with the disease, even "thinking that he was going to die" during the first two weeks of the infection. He returned to training in February but could not make it for the bout's third attempt on March 13.UFC President Dana White invited Khamzat Chimaev to get better treatment for his symptoms in the United States, but it seems that all the effort was to no avail as he seems to be still severely affected by the disease.Khamzat Chimaev tried to convince himself and fans that he was completely recovered from COVID-19. He restarted his trash-talking during February and even was recorded in a video while punching some heavy bags in training."Now I'm back to a hundred percent. My lungs are good. We work hard day after day. I've always worked hard, but we have never trained for five rounds before. Now I train extra hard with longer sessions. I want to smash him [Leon Edwards], brother. I want to destroy him," Khamzat Chimaev said ahead of the third cancellation.