The streets of Ayrshire could be locked down until at least June, health bosses have today warned.Scotland's chief medical officer said that restrictions placed on movement amid the Covid-19 crisis may be in place across the nation well into the summer.Dr Catherine Calderwood said that "some sort of measures" were needed for "at least 13 weeks" to stop the disease spreading.It follows a similar warning from the chief scientists advising the UK government, who said lockdown measures should not be lifted until June at the earliest.Dr Calderwood said that any lifting of the lockdown at this stage was likely to risk the virus continuing to spread.Speaking on BBC Radio Four's Broadcasting House, she said restrictions of less than 13 weeks could