The Welsh first minister, Mark Drakeford, has said it is the right time for his country to emerge from its 17-day “firebreak” despite sharp rises in Covid cases and the decision by the UK government to begin a lockdown in England. Drakeford said the impact of the Welsh firebreak, which ends on Monday, would not be felt for a week or two but expressed confidence that Wales’s early action means the country will get to Christmas without a further national lockdown. In an interview with the Guardian, the Labour leader in Wales took a swipe at Boris Johnson for repeatedly insisting that an end to the crisis is in sight, claiming this undermined trust. Drakeford said the pandemic had changed the state of the union for ever, but argued it had shown not that Wales should become an independent country but that it already had the powers to make its own decisions. There will be more freedom for people to meet in Wales from Monday when a new set of national rules comes into force and pubs, cafes and restaurants will reopen. But the changes come at a time when there are as many Covid patients in Welsh hospitals as there were in April, and cases in some areas, particularly in parts of the south Wales valleys, have soared. Drakeford said: “Our decision to go for a 17-day firebreak was based on the advice we had at the time. As long as we were really strict about our firebreak, three weekends and two weeks would be enough to suppress the virus. “The impact of the firebreak will not be felt for another week or two, but we continue to follow the science and follow the advice.” Data from Wales’s Techinical Advisory Cell (TAC) suggests people have respected the firebreak with movement back down to the levels seen in May. Drakeford said: “We took a difficult decision, given we were doing it on our own. We struck a bargain with people then if we made it as strict as we needed to, it would last for the 17 days. A lot of people at the time asked, was it necessary? Now I see people saying we haven’t done it for long enough. You have to set out your stall and hold your nerve. Our ambition was to find a pathway through the rest of this calendar year.” Provided people stuck to the firebreak and now follow the new rules, he said the country should be able to get through to Christmas without another national firebreak or lockdown, but he said it was “not helpful” to speculate what may be needed in the new year. “Many more things will emerge we have not thought of,” he said. Drakeford refused to be drawn on when the crisis may be over and criticised Johnson for making over-optimistic predictions. “It will be over when we get a vaccine that offers people more than a modest amount of temporary protection. I think the prime minister has created a problem for himself in terms of trust and credibility by regularly suggesting we’re only a few weeks away from everything being fine again. [He said] it was going to be over in 12 weeks, it was going to be all over before Christmas. “Even when he was announcing the lockdown for England, he couldn’t resist a final flourish in which he claimed it would be over by spring. I think that corrodes people’s confidence in the message. I’m sure it seems attractive at the time for a few moments. In the long term it doesn’t add to the credibility of political leadership. “I don’t want to ever be in the position of saying to people in Wales it’s all just around the corner, this will be over soon. We’re going to have to live with coronavirus for a long time. There’s no magic bullet and I don’t think it helps to suggest to people there is.” The relationship between Cardiff and Westminster has been fraught at times during the crisis, not least when Wales banned people from Covid hotspots in other parts of the UK. Drakeford said the engagement between the governments had been better in recent days, but he said the crisis had changed the union for ever. “I think it will change the nature of the conversation in Wales. I’m regularly asked about whether there is a rise in enthusiasm for independence in Wales. I think coronavirus has shown that we have a Senedd with its own independent powers and a government that has been prepared to use those powers independently when we have felt it is in Wales’s interest.” The first minister has urged people to follow the new rules – but said this was only part of the job. “We don’t want people to think: ‘How far can I stretch the rules? What can I do? What more can I get away with? Everyone has to ask not what can I do, but what I should do.”