Sicily's coronavirus co-ordinator and nine other healthcare officials have been arrested suspected of taking bribes from equipment and services contracts, Italian police say.
The contracts go as far back as 2016 and total nearly €600m (£540m; $660m).
Palermo Mayor Leoluca Orlando called it "an extremely serious corruption system". It allegedly involved creaming off 5% commissions on public contracts.
It is alleged the bribes promised total at least €1.8m, Italian media report.
The head of Sicily's coronavirus response, Antonio Candela, is now under house arrest while Fabio Damiani, who heads the Trapani's health authority (ASP), is among those in police detention.
Italy - especially Lombardy in the north - has been one of Europe's hardest-hit countries by Covid-19. The pandemic has put Italy's health service under severe strain in terms of staff, equipment and finances.
The Palermo magistrate also ordered the seizure of seven companies, based in Sicily and Lombardy, and of €160,000 in bribes already paid.
Col Gianluca Angelini of the financial police said they had discovered "a true centre of power… in which dishonest public officials, unscrupulous businessmen and entrepreneurs are willing to do anything to obtain contracts worth millions".