The World Health Organization's special envoy on Covid-19 has said the world cannot wait for universal testing or a vaccine to "come out of lockdown" and people will have to find new ways to live with the threat of the virus in their lives.

Dr David Nabarro said people will need to find ways to go about their business, otherwise we will be "paralysed" by the virus.

He said getting everyone on board and learning to live with this "as best we can" knowing that the coronavirus has not gone away, is key to reducing restrictions on social and economic activity.

Speaking on RTÉ's Today with Sean O’Rourke, Dr Nabarro said it is an impossible task for everyone to be tested and the virus is "not going to stop and wait for tests so we need to defend ourselves in the midst" of it.

He said communities will have to be vigilant and find people with the disease, isolate them quickly and trace and isolate their contacts.

He said a lot depends on our own responsibility to decide not to go out to a gathering or to work if you have symptoms like a cough or a temperature and it will be our civic duty to act responsibly both collectively and individually to help protect against "such a vicious virus".

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Yesterday, Minister for Health Simon Harris said the more progress that is made here over the next three weeks, the more likely it is that the Government can begin to tweak some of the restrictions that are currently in place.

However, he said this does not mean going back to life before Covid-19, because "it is still going to be here".

"There isn't going to be a magic point at the start of May, where life as we knew it can resume."

He said that social distancing is going to remain a "very big part of life", until an effective treatment or vaccine can be found.

Dr Nabarro said wearing face masks is one means of defence against the spread of Covid-19 and masks will need to worn by health workers, the sick and those who work closely to other people in the workplace, including hairdressers and those working at checkouts in supermarkets. 

He said he suspects many will want to wear masks going about their everyday life to protect themselves and "to show they are taking it seriously". 

He said a homemade mask will not provide absolute protection, but will provide an opportunity to limit spread. 

Dr Nabarro said society will have to work out how large social gatherings can take place again.

He also said a vaccine for the coronavirus is difficult to produce and a solution in producing a large-scale vaccine is not going to happen soon. 

"This virus is not going to disappear and we need to learn how to protect ourselves," he said. 

Dr Nabarro also said he is "a super fan of what's happening in Ireland" and of the efforts made here to follow the WHO's guidance in relation to dealing with Covid-19. 

He said he is delighted to see an Irishman leading the emergency response in the WHO (Michael Ryan) and that the steps announced yesterday by the WHO would be followed in Ireland.