Now, as the virus sweeps through a country of 1.4 billion people who lack natural immunity having been shielded for so long, there is growing concern about possible deaths, virus mutations and the impact, again, on the economy.
Beijing reported five COVID-related deaths on Tuesday, following two on Monday which were the first fatalities reported in weeks.
Authorities have also been racing to build so-called fever clinics, facilities where medical staff check patients' symptoms and administer medicines.
In the past week, major cities including Beijing, Shanghai, Chengdu, and Wenzhou announced they had added hundreds of fever clinics, according to government WeChat accounts and media reports.
A survey by World Economics showed on Monday China's business confidence fell in December to its lowest since January 2013.