From midnight, Austrians have been asked to work from home and non-essential shops have closed.
New restrictions have sparked protests throughout Europe. People clashed with police in the Netherlands and Belgium.
Infection rates have risen sharply on the continent, prompting warnings from the World Health Organization (WHO).
On Saturday WHO regional director Dr Hans Kluge told the BBC that unless measures were tightened across Europe - such as on vaccines, wearing masks and with Covid passes for venues - half a million more deaths could be recorded by next spring.
Last week Austria became the first European country to make Covid vaccination a legal requirement, with the law due to take effect in February. Politicians in neighbouring Germany are debating similar measures as intensive care units there fill up and case numbers hit fresh records.