VIENNA—Tens of thousands of protesters marched through Vienna on Saturday after the Austrian government announced a nationwide lockdown beginning Monday amid a rise in coronavirus infections. Demonstrations against virus restrictions also took place in Switzerland, Croatia, Italy, Northern Ireland, and the Netherlands on Saturday, a day after Dutch police opened fire on protesters and seven people were injured in rioting that erupted in Rotterdam. Protesters rallied against coronavirus restrictions and mandatory COVID-19 passes needed in many European countries to enter restaurants, Christmas markets, or sports events, as well as mandatory vaccinations. The Austrian lockdown will start Monday and comes as average daily deaths have tripled in recent weeks and hospitals in heavily hit states have warned that their intensive care units are reaching capacity. The lockdown will last at least 10 days but could go up to 20, officials said. People will be able to leave their homes only for …