(Bloomberg) -- An influenza outbreak in China picked up intensity over the past week as a major city prepared to enforce pandemic-style lockdowns to curb the surge in infections.

The positivity rate for flu jumped to 41.6% in the week beginning March 5 from 25.1% the previous week, the Chinese Center for Disease Control and Prevention said in its weekly Covid surveillance report on Saturday. The Covid positivity rate was down to 3.8% from 5.1%.

The northwestern city of Xi’an said earlier this week it would employ measures similar to those used to curb Covid-19 as part of its plan to contain influenza outbreaks, with school and business closures included in the response. 

The city of some 13 million residents was locked down for a month in 2021 because of Covid, with residents largely barred from leaving their homes.

The positivity rate has increased for six consecutive weeks and started to increase more sharply in mid-February, according to government data.

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