4 week lockdown - why?

Krissie from Henderson

Hi all.

I am an essential worker with a BSc(hons) degree in Biomedical Science working in food safety/animal health, and the partner of another essential worker who works in a front line clinical environment. We're out there placing our household at increased risk to keep this AMAZING nation going through the lockdown, and ensuring it can still keep going afterwards.

With that in mind, I just wanted to offer some information about the likely reasons that the Government has talked about this being a 4 week lockdown, about the COVID-19 virus (more correctly: SARS-CoV-2) and why the Government has stated that the lockdown could last longer than 4 weeks. I personally find that having some understanding of it all helps me feel a little bit better about it, and thought that others might feel similarly.

So, first thing's first, the virus:
A virus is just a small package of a few molecules. Fundamentally, it' a genome wrapped in a protein shell, with a few proteins sticking out to allow for attachment and entry into host cells. It can't replicate outside of a host, and uses the internal machinery of a cell to replicate. SARS-CoV-2 in particular is an enveloped virus, meaning that when an infected cell makes the attachment proteins of the virus, they are deposited in the cell membrane: As the assembled genome-containing protein shell of the virus leaves the cell, it takes some of this membrane with it, along with its attachment proteins. This is essentially why handwashing is so effective - because soap or strong alcohol can readily disrupt the lipid envelope which causes the virus to lose everything that makes it infectious. The fact that it's an enveloped virus also results in another lucky coincidence that could potentially see New Zealand eliminate it if we all stay safe: It cannot survive on surfaces for very long. For some surfaces/environments it might be a matter of minutes, and for others a matter of days, but no longer.

So why 4 weeks?:
The World Health Organisation has stated that the symptoms of COVID-19 (the disease caused by the virus) can take between 2 and 14 days to appear. They have also stated that a person may remain infectious for up to 14 days after symptoms appear, even if they begin to feel well again afterwards. Assuming somebody became infected on the first day of the lockdown (and didn't sadly die before it ended, which is unfortunately the reality we face)... every such person should in theory be clear of the virus again by the end of the lockdown. The virus cannot spread unless it can infect people, and if we reach a point where nobody has it, we've eliminated it from New Zealand.

Why could it be longer?:
The Government has stated that 4 weeks is the earliest reasonable timeframe in which it could hope to have achieved its aim of eliminating the virus from daily life. There will, of course, be new cases entering New Zealand as Kiwis return home from overseas. In addition, there will also be those who misunderstand the lockdown requirements, or worse, openly flout them. Finally, there are also the workers in essential services who may be at increased risk despite that risk being managed by the introduction of safer working practices. Each of these factors represents a possible way for the chain of transmission to be extended. If the chain of transmission is extended, the lockdown must be extended.

What happens after?:
Unfortunately, nobody can fully answer that question as we simply aren't there yet. However, we can reasonably expect that a heightened alert level will remain. Though the aim is to eliminate the virus, there will always be a risk that it hasn't been fully eliminated, or that it could be reintroduced anew. Most reasoned estimates for the time required for a new vaccine to be approved for worldwide distribution stand at a minimum of 18 months. So, we can assume severe border restrictions will last at least that long, (with perhaps some travel allowed for residents or for essential purposes, tied in with strict border quarantine requirements).

However, all this only works if people abide by the requirements of the lockdown. Regardless of how long it lasts, the sooner and more completely that happens, the sooner restrictions can be lifted. The sooner all this happens, the sooner our doctors, nurses, emergency workers, other essential services workers, and indeed, the country as a whole, can breath some small sigh of relief.

Kia Kaha, and stay safe everybody.