The Labour leader has backed extra restrictions aimed at curbing the rampant spread of the virus, but said they must be as "short as possible" so as not to have a negative long-term impact on communities.
And he warned that people could face going "in and out of restrictions for months on end" unless Ministers improved the country's flagging testing system.
Sandwell and Wolverhampton are currently in local lockdown, while Walsall, Dudley and parts of Staffordshire have all seen rising cases and could face new restrictions in the coming weeks.
Thousands of people across the region have struggled to get a Covid test, with some sent as far away as Scotland when they try and book online and others turned away from testing centres.
Sir Keir was due in Walsall today as part of Liam Byrne's campaign for West Midlands Mayor.
He told the Express & Star: "We have supported the Government with these measures and urge people to follow the restrictions.
"They do have a real impact and local communities are entitled to ask the government, what are you going to do to make sure the restrictions are as short as possible?
"People don't want to go in and out of restrictions for months on end. They need to know that they will get better protection from the Government."
Sir Keir, who replaced Jeremy Corbyn as Labour leader in April, returned to work last week after self-isolating while a family member awaited test results.
He said issues with testing were part of a "catalogue of incompetence" from Ministers that had "badly let down" people in the Black Country and Staffordshire.
"The Government needs to get on top of testing now, but instead of accepting there is a problem the Prime Minister is pretending it is all a stunning success," he said.
"My message to him is don't make a promise for tomorrow, deal with the problem today."