There are 52 confirmed with 30 probable cases of Covid-19, Director-General of Health Ashley Bloomfield says. That brings the total number of confirmed and probable cases in New Zealand to 950.
A renowned New Zealand expert in viral immunology says he's encouraged at the rapid pace of global efforts to find a vaccine against Covid-19.
But Professor Graham Le Gros still expects the process will be a lengthy one, given the time and care needed to ensure a vaccine will be safe for an entire population to use.
Le Gros, the director of Wellington's Malaghan Institute of Medical Research, said the most promising point of vaccine efforts to date was that antibodies appeared to be able to neutralise the virus.
"I have every faith that making an effective vaccine for this novel coronavirus is possible," he said.
"What we can't yet predict is how long it will be until such a vaccine is widely available.
"While there is plenty of news about work underway towards a vaccine, even the most optimistic predictions from top scientists put a safe and effective vaccine that can be mass-produced at least 18 months away."
There also remained a few tricky aspects of the virus, including how it infected people and effectively hid from the immune system.
"We don't know whether or how the virus will evolve and we don't know whether there's protective immunity once you've had infection.
"What is essential now is research – global, collaborative research – to understand this virus, and for communities globally to follow health guidelines to minimise the virus's impact."
Professor Graham Le Gros is encouraged at the pace the world is racing to make a vaccine to stop Covid-19. File photo / Mark Mitchell
One potential candidate for a vaccine, developed by scientists at the University of Pittsburgh in the US, was tested in mice through a fingertip-sized patch and was found to produce virus-specific antibodies in quantities great enough to stop it.
Similarly promising, researchers at the Peter Doherty Institute for Infection and Immunity in Melbourne have shown how the body can fight the virus and recover from the infection.
By testing blood samples of a healthy woman in her 40s, who had mild-to-moderate symptoms of Covid-19, scientists were able to observe an immune response across different cell types, which could also prove the secret to a new vaccine.
In another new study, scientists at California's Scripps Research Institute used an antibody recovered from a survivor of the Sars epidemic in the early 2000s to reveal a potentially vulnerability in the new coronavirus.
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That also pointed to the possibility that other antibodies linked to Sars-CoV may also hold the key to neutralising the Sars-CoV-2.
"But what we don't know is how parts of the immune response to the virus works at different stages of life," said Le Gros, who is involved in a fledgling New Zealand effort to make a vaccine.
Covid-19 had been shown to trigger what are called cytokine storms – an over-reaction of the body's immune system which could prove harmful and sometimes lethal.
Le Gros said the same mechanism that our bodies used to fight cancer – namely T-cells, which controlled the degree of cellular immune responses – was what kicked this effect off.
"When they start seeing viruses, they just kill everything, and cause a lot of destruction by releasing hormones that make the whole body shut down," he said.
"So we know that we can make an antibody response, but we've got to be careful, because we don't want to hurt people who are otherwise well."
Le Gros said he'd been interested in work that showed that simply stimulating someone with a bacterial infection could invoke a strong type 1 immune response.
"There's a possibility that we could raise just enough of what we call innate immunity that it actually reduces many of the symptoms of the virus and leads to a very mild infection."
He said some groups of scientists were attempting to shorten the push for a vaccine by bypassing traditional methods, which typically took years.
"Some of these efforts aren't even really vaccines as such, but more kinds of immune therapies, in which they might vaccinate an animal, purify the antibodies, and then make these fragments and insert them into people.
"We have to be very careful with vaccines, especially around who we are trying to vaccine. Is it the general population, or people who are quite susceptible? It's a big deal to roll out.
"Normally, making a fundamentally new vaccine and bringing it into the system would take five years. There's a rationale and justification in fast-tracking it for those people who are at very high risk, or who are very sick, but otherwise, we need to take a lot of caution."
Meanwhile, Le Gros said we could help our immune systems by eating a well-balanced diet and leading healthy lifestyles.
"And I'm sorry, but supplements won't boost your immune system. It's antigens and bugs that stimulate that."
