Austria will enter a full national lockdown from Monday, following a surge in coronavirus cases.
Ministers say it'll initially last for 10 days, but could last up to double that.
Countries such as Germany, Slovakia and Greece have also brought in tougher coronavirus measures - but Austria has become the first European country to return to a full lockdown this autumn.
School children will be asked to return to remote learning where possible, but schools will remain open for children of parents with essential jobs or for students with special needs.
Austria had previously introduced strict restrictions for unvaccinated people, with the full lockdown coming just days after those measures were introduced.
The country has also announced that COVID-19 vaccines will become compulsory, with the measure coming into effect from February 1st.
It will become the first European country to make vaccines mandatory by law.
Announcing the measures, Austrian Chancellor Alexander Schallenberg said the new rules are aimed at avoiding a fifth wave of cases.
He said the country had failed to get enough people vaccinated, and sharply criticised politicians who had supported anti-vaccine messages.
Austria so far has reported a 69% vaccine uptake rate across the entire population, compared to 77% in Ireland.
Austria's announcement comes on the same day new COVID-19 measures come into effect in Ireland, including a return to work from home and a new midnight curfew for bars, restaurants and nightclubs.