There is now a 95% chance COVID-19 has been eliminated in New Zealand, according to our modelling, based on official Ministry of Health data.
As of June 4, New Zealand has had 20 consecutive days of zero new cases, with only one active case remaining.
New Zealand is now preparing to relax its COVID-19 restrictions to alert level 1 from as early as next Wednesday, which would end physical distancing and size restrictions on gatherings. But our modelling suggests removing limits on large gatherings will increase the risk of a very large new outbreak from 3% to 8%.
To reduce this risk, New Zealanders will need to continue avoiding the three Cs of possible infection: closed spaces, crowded places and close contact.
As crowds return, the risks will rise in New Zealand
New Zealand is now very close to its elimination target. But there is still a 5% chance of undetected cases.
From the perspective of the virus, the most significant change will be the end of restrictions on the size of gatherings. Airlines can fill up economy class again, nightclubs can pack their dancefloors and universities can open their lecture theatres.
Someone who caught the virus three or four weeks ago may not have developed severe symptoms (which happens in around 30% of people) and not got a test. They could have passed the virus on to someone else, who also missed out on a test.
A chain of infections like this could continue for a while before it is detected. Some segments of the population, such as younger people, are less likely to develop symptoms and are therefore more likely to sustain hidden infection chains.
COVID-19 is a superspreading virus. The reproduction number (R0) tells us that on average each infected person infects another 2.5 people. But for every ten people who catch COVID-19, nine probably won’t pass it on, while the tenth person may turn up at an event and infect 25 others.