The swift response to an outbreak of Covid-19 in Beijing shows that the lessons of the fight against the virus have been learned. Dozens of cases have been confirmed, all linked to a wholesale food market in the city’s Fengtai district, prompting authorities to go onto what amounts to a war footing. The facility has been closed, surrounding neighbourhoods locked down and mass testing carried out while an exhaustive investigation into finding the cause takes place. This is how any responsible government needs to react to the coronavirus to prevent a much-feared second wave of infections. Vice-Premier Sun Chunlan, who has been overseeing the nation’s Covid-19 response since January, called on officials to take “decisive measures” and warned that the risk of further spread was high. She is only too aware of what happens when there is inadequate vigilance; she was sent to Wuhan, where the first outbreak in China occurred, to restore confidence after accusations of a cover-up by local authorities. The city and Hubei province pioneered the nation’s approach to the infectious disease with strict lockdowns, quarantining, isolating and testing. With the national capital now being the site of a large Covid-19 cluster, all that has been learned from five months of dealing with the virus is being put into practice. Beijing braces for ‘explosive Covid-19 outbreaks’ as market cases mount No nation is better equipped to confront outbreaks. Finding the source will be important; while an initial investigation of genome sequencing shows the virus came from Europe, determining how it got to the market and was able to spread so rapidly is what matters most. The infection was discovered on chopping boards in shops that sold imported frozen salmon, prompting supermarkets to take the fish from shelves and diners to be wary of it in restaurants. But such a response is based on speculation and only after thorough scientific research can the source be determined. Beijing had not had a case of Covid-19 transmission for 55 days until Thursday when a man, who did not have a history of travel or contact with people arriving in the capital, was confirmed as being infected. He and another confirmed case, a meat inspector, had been to the market earlier this month, prompting mass testing and the discovery of dozens of other sufferers. Knowledge about the virus is constantly being gleaned and theories abound about how frozen food and packaging can support and prolong the life of the virus. But that is not proof it came from the fish; it could also have come from someone with the disease coughing on food or other people. The fresh cluster has surprised some Chinese who thought the nation’s successes in fighting Covid-19 meant it had been conquered. But its re-emergence and the rising number of imported cases prove that guards can never be let down.