Rome: The results of nationwide antibody tests conducted on nearly 65,000 Italians indicate that some 1.5 million individuals or 2.5% of the population have had the coronavirus, health officials said on Monday.

That figure is six times the number of confirmed cases in Italy's official virus tally. The results - viewed with the country's overall death toll of close to 35,000 -align with the 2.3% estimated mortality rate of the virus.

Dr Franco Locatelli, a key scientific government adviser, said the tests were designed to understand the virus' circulation nationwide and not whether Italians with antibodies were safe from the virus.

The huge geographic variability in the results - some 7% of residents in hard-hit Lombardy had the virus versus 0.3% in Sicily - showed that Italy's three-month nationwide lockdown was critical to sparing parts of the country the devastation experienced in the north, he said.