Unfortunate that it doesn't allow you to get back to zero.
Various countries have managed to do it, including China with hard lock downs.
b) getting back to zero does not mean staying at zero. China has had long stretches of time with zero reported cases of local transmission, punctuated by brief outbreaks like the current one.
That's different from people who get infected in China. There have been long stretches of time with zero local cases in China.
Just to illustrate the difference, here's a typical daily report from China's main public health authority:[1]
> BEIJING, June 28 (Xinhua) -- The Chinese mainland on Sunday reported 21 imported COVID-19 cases but no new locally transmitted cases, the National Health Commission said in its daily report on Monday.
The "imported cases" are among travelers undergoing quarantine.
There have been a few outbreaks with local transmission, but so far, all of them have been successfully contained before they spread very far. Right now, for example, there's an outbreak in a town on the border with Myanmar. The town itself has been locked down and everyone in it (270k people) has undergone PCR testing, and will be tested a second time over the coming days. So far, about two dozen infected people have been identified. However, outside of this town, there are currently zero local cases in China.
1. http://www.xinhuanet.com/english/2021-06/28/c_1310031605.htm
This would simply be impossible if there were community spread of the virus inside China. With open restaurants, theaters, etc., the virus would spread like wildfire in China's dense cities, and everyone would know about it. The strict lockdowns in early 2020 worked to bring cases very near zero, and they were followed up with mass testing campaigns (for example, nearly all 11 million residents of Wuhan were tested in June 2020) to find the last few infections.[1,2]
The common reaction among many people, to deny that China eliminated SARS-CoV-2 within its borders, simply isn't tenable.
1. "Post-lockdown SARS-CoV-2 nucleic acid screening in nearly ten million residents of Wuhan, China": https://www.nature.com/articles/s41467-020-19802-w
2. "Comprehensive large-scale nucleic acid–testing strategies support China’s sustained containment of COVID-19": https://www.nature.com/articles/s41591-021-01308-7