More than 74,000 new cases of the coronavirus were reported globally on Tuesday, the largest increase in a single day since the virus began and almost 30pc above the previous day's rise.
More than 850,000 cases and 42,000 deaths have been reported across 205 countries and territories, according to a Reuters tally on Wednesday.
Italy and the United States have reported a total of more than 100,000 cases each.
Germany's Bund yield was down 4 basis points at -0.497pc.
Most of the rest of the core euro area market also saw declines, with France and Belgium seeing rates steady.
"I think it's a great opportunity to get into the European bond market as you have a guarantee from the (European) Central Bank" that it will continue buying government bonds amid its hefty stimulus package, said Marija Veitmane, mult-asset strategist at State Street Global Markets.
"By expanding the QE (quantitative easing program), the ECB are there to support the peripheral European markets," she said.
Portugal sold seven-year bonds on Wednesday via a syndicate of banks, as national treasurers in Europe come under pressure to finance government rescue programs being mounted to fight an economic downturn caused by the spread of COVID-19. By mid-morning, the order book had reached 24 billion euros.
Portugal's 10-year government bond yield was last up 1.2 basis point to 0.847pc, having reached earlier a six-day high of 0.871.
Spain was the first euro zone member country to tap the primary market with a seven-year bond last week.
And Belgium saw record demand for its bond sale on Tuesday. Investors placed orders of over 58 billion euros for Belgium's 8 billion-euro sale of seven-year bonds, according to a lead manager update seen by Reuters, making it the largest-ever order book for a euro zone bond sale.
Lyn Graham-Taylor, fixed income strategist at Rabobank, said there was a strong risk-off mood across the financial markets on Wednesday.
The market can't "look around the corner" for a significant improvement in the euro zone economy given recently weak data and the lack of encouraging news about the coronavirus, he said.
Data on Wednesday showed euro zone manufacturing activity collapsed last month as breaks in global supply chains caused by measures to curb coronavirus crushed output.
The nosedive could worsen in coming months, a survey showed on Wednesday.