Shanghai cases up, third of US cases BA.2

| March 23, 2022

Coronavirus infections have hit a new daily high in the Chinese city of Shanghai as a study estimated about a third of cases in the United States were of the BA.2 variant.

China’s financial hub Shanghai on Tuesday reported a fifth consecutive daily record for locally transmitted COVID-19 asymptomatic cases amid the highly infectious Omicron variant.

Although small compared with outbreaks in other countries, the rise is significant as Shanghai redoubles its efforts to implement China’s “dynamic clearance” policy designed to curb each flare-up.

The city is pressing ahead with a block by block testing scheme after already completing more than 30 million tests.

Shanghai reported 865 domestically transmitted asymptomatic infections for Monday, official data showed, up from 734 a day earlier.

The municipality also reported 31 new local cases with confirmed symptoms, which China counts separately, on Monday, including one person who was initially reported as an asymptomatic infection and showed symptoms later, according to data from the National Health Commission.

Chinese authorities have warned local governments against slackening in their virus control efforts and reiterated that infections should be identified and isolated quickly, while acknowledging that officials should minimise the economic and social impact of COVID-19 restrictions.

The NHC said on Tuesday that cities, including those with more than 10 million residents, must be able to complete a testing campaign within 24 hours, while its extent should be tailored to the need for COVID-19 control and not necessarily blanket testing.

Including the infections in Shanghai, mainland China reported on Monday 2281 new locally transmitted cases with confirmed symptoms, the NHC said, compared with 1947 a day earlier.

In the US, the Centers for Disease Control and Prevention (CDC) on Tuesday estimated the BA.2 sub-variant of Omicron made up more than a third of all coronavirus variants circulating in the country.

COVID-19 infections in the US have receded sharply since hitting record levels in January, although a coronavirus resurgence in parts of Asia and Europe due to the BA.2 sub-variant has raised some concerns.

As of March 20, the seven-day moving average of US COVID-19 cases was 27,786, down 17.6 per cent from a week earlier.

Most of the US is considered to have low transmission, under new CDC guidelines introduced last month, which emphasised hospitalisation rates and advised most people they no longer needed to wear masks.

Other Omicron sub-variants that have been circulating since December – called BA.1.1 and BA.1.1.529 – now make up about 57.3 per cent and 7.9 per cent respectively of circulating variants.

BA.2 was shown to be more transmissible than Omicron’s more common BA.1 variant in initial data. 

But there appears to be no significant difference in disease severity, the World Health Organisation said last month.