Thomas Seitz, 53, is “according to his doctors expected to make a swift recovery,” national news agency DPA reported, quoting a statement.
Seitz was in November threatened with a fine by deputy speaker of parliament Claudia Roth, when he took to the stand in the Bundestag wearing a mask with holes.
Roth offered him an FFP2 mask instead of his net-like mask, but Seitz had complained about the “muzzle”.
The far-right party has in recent months vocally opposed measures including mask-wearing or social contact limits put in place by Chancellor Angela Merkel's government to halt transmission of the virus.
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AfD co-leader Alexander Gauland had accused her government of a “corona-dictatorship” while some AfD MPs have marched alongside demonstrators protesting the restrictive measures.
Nationwide, regions where the AfD attracted most support in the last elections were also reporting the highest rates of infections.
In the worst-hit Bautzen or Görlitz regions, where one in four people voted AfD, incidence rates are now at above 600 per 100,000 people — more than three times that of the national rate of 179.
German media also reported over the weekend that an AfD city councillor in the Saxony town of Böhlen, Harald Haenisch, succumbed to the virus after he was hospitalised and put on a ventilator.
While confirming his death, the town's mayor had declined to state the cause of the death.
Haenisch had demonstrated against coronavirus curbs, including at a large protest in Berlin that turned violent.
Germany went into a partial lockdown from Wednesday, with non-essential shops and schools shut in the hopes of halting a surge in coronavirus infections.
On Thursday, Europe's biggest economy reported another record in daily new infections, surpassing the 30,000 mark for the first time.
Germany has recorded a total of 24,125 deaths, up by about 700 in one day.