LONDON (Reuters) – England’s test and trace system identified 31,794 people who had been in close contact with someone who had tested positive for COVID-19 in its first week of operation, the government said on Thursday.

Some 85% of them were reached by the government’s new army of contact tracers and told to self-isolate for two weeks.

Prime Minister Boris Johnson’s government, facing heavy criticism for its handling of the pandemic, has touted the scheme as the way to ease lockdown measures while keeping the coronavirus spread in check.

Other countries in the United Kingdom have similar programs to the one in England. Program leader Dido Harding said the service was already working at scale and would step up over the summer.

“Is it completely perfect? No of course it isn’t,” she said. “But I think it is fit for purpose as we stand today.”

The program handled 8,117 people who tested positive for coronavirus between May 28 and June 3, of whom 5,407 were asked to provide details of recent contacts, the government said.

The contacts, who typically would have been within 2 meters of the person who tested positive and for more than 15 minutes, were traced by local health protection teams, newly recruited staff and online.

Harding said more than three quarters of contacts were reached and agreed to self-isolate within 24 hours of being identified.

“We are not at the gold standard yet that we want to be of isolating all contacts within 48 hours of someone requesting a test, but you can absolutely see the path of how we get there,” she said.

A smartphone tracking app will be added in the coming weeks, although the government has not specified when.

Britain is one of the countries worst hit by the coronavirus. By Tuesday the death toll neared 52,000, according to a Reuters tally of official data sources.