The Republic of Ireland and Northern Ireland administrations have signed a memo formalising their co-operation in the battle against coronavirus.
A memorandum of understanding (MOU), which has been signed by the two departments of health, focuses on facilitating greater co-operation on messaging, research and public health measures.
Other areas will also be considered including procurement.
It comes following apparent confusion when Stormont Finance Minister Conor Murphy said he had agreed a deal with Dublin for an order of Personal Protective Equipment from China which did not materialise.
The Republic's Department of Health later said it had not been possible to place the joint order, due to what it said was "the context of what is an increasingly challenging international environment" for such equipment.
The new memorandum was agreed by Minister for Health Simon Harris and his counterpart in Northern Ireland, Health Minister Robin Swann, as well as the two chief medical officers - Dr Tony Holohan and Dr Michael McBride - and has the support of both administrations.
Mr Harris said there has already been "significant engagement" throughout the pandemic.
"This MOU will ensure timely and responsive communications and decisions in a fast-moving environment; that both administrations will seek to adopt similar approaches, where it is appropriate to do so on the advice of respective chief medical officers," he said.
"I want to thank my colleagues in Northern Ireland for their co-operation to date. This is a global pandemic. It knows no borders and we are all in this together. It is essential we continue to do everything we can across the island to fight this pandemic."
Mr Swann added: "I want to acknowledge the ongoing collaborative work between my department, the Public Health Agency and Health and Social Care Board and their counterparts in the Republic of Ireland.
"This has been the case from day one and is a reflection of the long-standing cooperation and relationships built up over many years.
"We face a common challenge, a challenge that will test us as never before.
"We will continue to do everything possible to work together for the best possible outcome."
Dr Holohan added: "We have been working closely with our Northern Irish colleagues since the start of the Covid-19 crisis. Today's MOU will formalise the close ongoing co-operation that has been taking place."
Dr McBride said it is essential the two administrations work together over Covid-19.
Northern Ireland First Secretary Arlene Foster said the executive is engaging with counterparts in London and Dublin as well as having discussions with the Chinese Consul General, Zhang Meifang, on securing more equipment to support healthcare staff and sharing medical expertise.
"The concerns about PPE are being treated extremely seriously by this executive," she said.
"The first batch of a fresh order from the NHS was delivered to Northern Ireland on Monday 6 April comprising some 5.5 million items in total.
"However, we know that we need to replenish and increase the stock that we hold, given the expected level of demand in the coming weeks.
"Efforts to source more PPE are continuing, and this is a constant focus of our executive meetings. The Minister for Health is actively working with the Minister of Finance to pursue all feasible supply routes, both international and local. It is a global challenge."