Covid-19 NZ: Is it really a good idea to call Omicron ‘mild’?

Is Omicron really ‘mild’? Or is it just ‘milder’? Keith Lynch attempts to quantify the risk Covid poses and explains the ‘mildness’ conundrum is, well, complicated.

There’s a single word that keeps popping up when people talk about Omicron – “mild”.

For most people, Associate Health Minister Ayesha Verrall has said, Omicron would be a mild to moderate illness.

Prime Minister Jacinda Ardern said very much the same on Sunday while announcing the red traffic light setting: “ … because of vaccinations, for most people it will be a mild to moderate illness that you can manage at home”.

READ MORE:
* Covid-19 NZ: Omicron is here. This is what happens next
* Covid-19: Inside an Omicron wave – understanding the rise and fall
* Covid-19: The NSW Omicron outbreak is not what you think

If you ran an Omicron branding focus group (“break into teams and pick a word to describe the virus”), it’d certainly appear. Just like Volvos are “safe”, Omicron is thought of as “mild”.

Google “Omicron” and “mild” and you’ll see more than 1 million results. The headlines include: “Is Omicron really mild?”, “How Mild is Omicron, really?”, “Omicron severity: milder but not mild”. There are countless social media threads where users scold others for suggesting Omicron is “mild”.

The m-word was once a docile, forgetful adjective typically used to describe Auckland winters or the meal you ordered on Saturday night.

Now, it’s very much embedded in our Covid-19 discourse. As The Atlantic reported in December: “Medically, the term ‘mild’ originated as an academic catchall for all SARS-CoV-2 infections not severe enough to get someone admitted to a hospital.”

The word “mild” has become highly contentious, even politicised. It has been used as a catch cry by those who want to drop all public health restrictions. ‘’Omicron is the common cold!’’ essentially implies “why are we bothering with these masks?”.

On the other hand, some public health professionals have over-played Omicron’s severity – seemingly ignoring evidence that it’s much less dangerous than Delta.

What’s more, the word “mild” is somewhat subjective. Merriam-Webster defines it very simply: “not severe”. It is clearly ridiculous to tell the family of a person who died or ended up in ICU with Omicron that the virus is “not severe”.

Tell a nurse in a month from now Omicron is “not severe” and see what the reaction is. (Don’t do this in real life. I’m just making a point.)

But at the same time, it’s somewhat inane (and arguably counterproductive) to tell a healthy, triple-vaccinated 20-something that Omicron presents a severe threat to their life.

Context also matters when it comes to how we think about “mildness”. A person in Ireland may well look at the Omicron outbreak as relatively mild. Of the 6000 or so people that have died during the pandemic there, relatively few have been during the recent wave.

But only about 50 New Zealanders have died with the coronavirus. It’s very likely the death toll will rise in the months ahead. Therefore, it is understandable many New Zealanders won’t see Omicron as mild – even though Aotearoa’s fatality rates will simply never be comparable to the likes of Ireland, the United States and Britain.

This “mildness” conundrum is partly why Omicron is so disorientating.

Think of it this way: you’re at least double-vaccinated and there are two rooms. In one of the rooms is an infectious person who has the Delta variant, and in the other is a person with Omicron. You have to enter one of the rooms. Which one?

Covid-19 modeller Professor Michael Plank outlined this example to me to understand the dizzying risk Omicron poses. He felt he’d rather go into the room with Delta. He’s less likely to walk out with an infection. But if he’s guaranteed to contract Covid-19, he’d rather leave with Omicron.

We’ll stick with individual risk for a moment, something that’s far from straightforward.

A range of factors from gender to comorbidities have an impact on how likely someone will get very ill with Covid. And when there are hundreds of thousands of cases all at once, some people who are statistically unlikely to get very sick – that is likely to have a “mild” illness – just get really unlucky. Toss a coin often enough, and eventually it’ll land on its edge.

Two variables dominate: age and vaccination status. The older you are, the more likely you will face serious outcomes from Covid. And vaccines make you significantly less likely to get seriously ill.

For example, in a social media post, Professor Paul Glasziou of Bond University in Australia suggested the chances of dying from Omicron for someone who has had at least two doses are likely similar to the flu. Some reporting suggests the risk to the boosted is actually even less.

Can you give me some hard numbers?

We’ll do our best, but it is early days. The data we present here is being used to get a read on what the impact of Omicron could look like on a population level.

Therefore it’s best to think of the hospitalisation rates as illustrative – they certainly don’t account for your, or a specific group’s, individual risk. The numbers are also based on international inputs that may well change. We don’t have New Zealand-specific data yet.

To offer up the range of scenarios on how Omicron could affect New Zealand, Covid modellers need to get a read on how severe Omicron is to both the vaccinated and unvaccinated.

Severity was easier to account for when the original variant, which is called wildtype, started spreading in 2020. There was Covid and there were people. There was no immunity.

Today, getting a complete read on severity is much trickier.

Given what we’ve seen overseas, Plank estimates when it comes to hospitalisations, Omicron poses about three-quarters the risk that the wildtype variant posed back in 2020 – assuming someone gets infected.

Let’s just dwell on this for a moment. Yep, this means Omicron is intrinsically less dangerous (after infection) than the first variant but not by that much. You probably recall that early 2020 wasn’t very pleasant. You might recall hundreds of people dying daily in Italy and Britain. You probably didn’t think that variant was all that mild.

If Omicron had spread through New Zealand in March 2020 via 5 million immunologically naive people, it would not be mild. It would be a disaster.

The only reason Omicron can credibly be described as “mild” is because of the vaccines. Incredibly successful inoculation programmes are why Ireland, Denmark and the UK have been able to lift all Covid restrictions.

Below, you can see an approximation of risk in different age groups, based on data provided by Plank. We’ve compared Delta to Omicron and you can see the difference the current vaccines make.

The vaccine effectiveness is sourced from UK data. There’s a temporal aspect to this – if you had your second dose six months ago you may be less protected against hospitalisation than someone who had it recently. (There’s also a chance we could be underestimating how good two doses is at preventing hospitalisation.)

Just to be clear, what you can see below is the risk of hospitalisation if a person is exposed to the virus. If you are infected, the risk of hospitalisation goes up slightly, but it’s still very low in most boosted age groups.

But there’s certainly still a risk, particularly to the elderly, which is why boosting this age group is of utmost importance.

It’s not all about individuals though, is it?

Yes. You are right. Let’s go back to Glasziou’s comparison to the flu again.

The problem with Omicron, as he notes, is that it creates so many cases so quickly. “In well-vaccinated countries … Omicron seems to be like having months of flu season compressed into a couple of weeks, swamping health care.”

This has been described as the “small percentage of a big number is still a big number” problem.

If there are hundreds of thousands of Omicron cases in a single week, and a good proportion of those hit the unvaccinated or elderly, you still run into big problems, particularly in a creaking health system.

This is why Omicron certainly hasn’t been mild in the US, where there are major immunity gaps. There, hospitalisations surged to all-time highs.

And this is why there are restrictions to slow down the spread.

This somewhat baffling confluence of individual and societal risk is why Verrall can credibly tell the nation: “For most people, Omicron [will] be a mild to moderate illness that you can manage at home” in the same press conference where she’s announcing significant measures to slow the spread of the disease.

It’s why Plank can say: “For most people, if you’re up to date with your vaccines, the risk of getting severely ill with Omicron is very low” in the same press release where his fellow academic Dr Matthew Hobbs says Omicron should not be thought of as mild, as it’s hospitalising and killing people.

There are, too, plenty of unknowns around the impacts of long Covid.

I asked University of Otago Professor of Biochemistry Kurt Krause if he thought Omicron was mild.

“I’d probably not say ‘mild’,” he said. “It’s more in the realms of seasonal influenza (in the fully vaccinated) and that kills tens of thousands of people in the US annually and affects millions.”

This is also why it’s not a good idea to seek out a Covid infection during the Omicron wave. Looking to get sick while the hospitals are struggling really isn’t the best call.

For the vast majority of vaccinated individuals who catch Omicron, yes it will almost certainly be mild, definitely milder than Delta. But for a society with immunity gaps that sees uncontrolled spread … not so much.