* Second round of COVID tests begins in Chaoyang district
* Beijing reported 31 infections on Tuesday vs Monday's 33
* Shanghai's month-long lockdown nightmare drags on
By Eduardo Baptista and David Stanway
BEIJING/SHANGHAI, April 27 (Reuters) - The second round of COVID-19 testing in Beijing's largest district began on Wednesday, with this week's campaign to screen most of the Chinese capital's 22 million residents so far detecting less than three dozen new infections a day.
Beijing residents have rushed to stock up on food and other supplies as the city races to stop a nascent outbreak and avert a city-wide lockdown like that which has paralysed Shanghai for the past month, leaving some in the Chinese commercial hub of 25 million venting extreme frustration.
Authorities in the capital have so far focused on early mass testing, whereas Shanghai waited for a about a month before launching a city-wide screening campaign.
In Beijing, Shi Wei, 53, a retiree, said he was encouraged by the city's low caseload so far, but nervous.
"These past two days every time I go to the supermarket there are lots of people, so I just turn around and leave, as I feel slightly unsafe," he said. "I can understand the panic, given what happened in Shanghai."
Beijing screened the more than 3.5 million residents of its Chaoyang district on Monday, all of whom are due for new tests on Wednesday. On Tuesday, 16 million from other districts were also screened and will be re-tested on Thursday.
It was unclear what percentage of those tests led to the detection Beijing's 31 new COVID cases on Tuesday, compared with the previous day's 33. No deaths have been recorded so far.
As of 8:00 p.m. on Monday, the results from 526,457 samples from Chaoyang available at the time came in negative. Officials have yet to publish all the results from Monday's test.
MONTH-LONG ISOLATION
Meanwhile Shanghai reported 48 new deaths on April 26, down from 52 the day before. That takes the official death toll to 238, all reported from April 17 onwards, although many residents have said relatives or friends died after catching COVID as early as March, casting doubt over the statistics.
The city's new local asymptomatic coronavirus cases fell to 11,956 from 15,319 the day before, with symptomatic infections dipping to 1,606 from 1,661.
Cases outside quarantined areas dropped to 171 from 217. Other cities that have been under lockdown began easing restrictions once such cases hit zero.
Shanghai's prolonged isolation has fuelled frustration over lost income, family separation and quarantine conditions, as well as access to health services and food. For many, the regular tests present the only chance to open their front doors.