A class-action lawsuit alleges that not enough is being done to protect Michigan prison inmates from the spread of the coronavirus, as testing results from state correctional facilities illustrate how quickly the virus can spread in a confined population.

The suit, filed on Wednesday against the Michigan Department of Corrections (MDOC) on behalf of the state’s 37,000 inmates, argues that they have “been denied proper and equal access to vital preventative measures to avoid the transmission of Covid-19”.

The complaint says that MDOC has failed to isolate sick inmates, provide adequate testing or cleaning and hygiene supplies, nor enforce social distancing. Inmates want the court to order the state to implement coronavirus guidelines advised by the Centres for Disease Control and Prevention.

For its part, MDOC has published a comprehensive plan to stop the spread and mitigate the impact of virus on its inmate population. The legal action and comments from inmates published by HuffPost claim not enough has been done.

Chris Gautz, a spokesperson for the department, refutes all of the claims put forward in the HuffPost article, in which he argues: “The department has been incredibly proactive in working to slow the spread and keeping our prisoners and staff safe.”

MDOC has released test result totals to date from across its prison system. The department says that it leads the nation when it comes to consistent testing of the prisoners — originally once they develop symptoms, but this has now expanded to whole prison populations where an outbreak has been identified.

Out of the total prison population in the state, 2,675 tests have been conducted with 1,395 confirmed as positive for Covid-19, 52 per cent of those tested, 39 prisoners have died.

Two correctional facilities stand out from the table of figures released. At Macomb, 83 per cent of the tested inmates were found to be positive, but only 109 had been tested to date and they were already displaying symptoms, so it is difficult to gauge the wider impact of the virus at that location.

However, at Lakeland, where the entire prison population has been tested, an alarming 56 per cent of 1,403 inmates were found to be positive, demonstrating the swift spread of the virus in a prison environment.

Mr Gautz say that the uptick in testing at Lakeland came about because they were particularly concerned about that population. Controlling the spread of the disease was difficult, as many prisoners were asymptomatic.

“The vast majority of prisoners who tested positive last week were confused as to how they were positive because they hadn’t had any symptoms,” Gautz told ABC13.

MDOC plans to reopen an unused facility to house the sick, to separate them from the larger prison population. The lawsuit asks the court to order the department to open other similar empty facilities to stem the spread of the virus.

Dan Manville, who is representing the plaintiffs in the class action case, writes: “Time is running out for the proper protections to be put in place.”

Similar worries have been reported across the US, with concerns that a prison environment, much like a care home, is an optimum environment for the spread of the virus.

Michigan has 40,399 confirmed cases of Covid-19 and has recorded 3,670 deaths.