Otago University evolutionary virologist Dr Jemma Geoghegan warns the coronavirus is "incredibly contagious".
"On average, one person infects three to four people. And then they go on to infect three to four people. So this is an exponential spread. And it is incredibly contagious," she tells Newshub National Correspondent Patrick Gower for his On Lockdown documentary.
Just how contagious this virus would prove to be was revealed as the Bluff cluster spread and spread. While around 70 people attended the wedding, ultimately it led to 98 cases.
One of those who caught the virus just by being at the same place at the same time is cyclist Adrienne, who had set off to bike the length of the country in February when there weren't even any cases in New Zealand. It wasn't even labelled a pandemic.
Starting at Cape Reinga, a month later, she had pushed through to Bluff - just in time to run into the wedding party there.
"A coach turned up and out piled all these people," she says. "I didn't talk to the bride and groom but I definitely interacted with some of the wedding party. There was a lot of interest in our bikes, some of them took photos for us, and we were taking photos for them. They had to take photos with my camera and then we'd take it back. I was eating at the same time. There was a lot going on."
She flew back to Auckland the same day Prime Minister Jacinda Ardern announced New Zealand would go into a level 4 lockdown. Then, she began to feel ill.
"I really struggled that week. I got to kind-of the Wednesday-ish and I couldn't get out of bed," she tells Gower.
"And then that following weekend there was in media stories about this Bluff wedding cluster and I was like 'ok, I wonder if this is a little more going on than feeling tired from riding my bike'.
"So that's when I went and got tested. And then later that week got the positive result back and yeah, I got coronavirus."
Adrienne went on to infect four family members in her bubble - but without the lockdown it would have been even worse, spreading to her co-workers and their families.
Watch the excerpt of Patrick Gower: On Lockdown in the video above.
