Today around lunchtime, the government will announce new measures it hopes will ease the burden on hospitals grappling with a second wave of Covid-19 infections and the seasonal flu. Keith Lynch and Kate Newton explain what we are up against with the latest Covid variant.
Covid is back. Well, it never really went away, but the… current iteration BA.5 appears to help fuel New Zealand’s second major wave, which is putting even more strain on hospitals in a stressed and painful winter.
On Wednesday, New Zealand reported: 11,464 cases and 729 people hospitalized with Covid-19. In response to this, the government will propose a number of new measures today. Why? That number of hospital admissions is perhaps the biggest concern.
Let’s start with the latest news about BA.5
The first figures suggest that those who have not yet had Covid are most at risk in the current wave.
READ MORE:
† Covid-19 NZ: How common are Covid reinfections (and how bad are they?)
† Omicron NZ: Why the government is doing (almost) nothing about Covid
† Covid-19 NZ: understanding the Omicron variant BA.5 and why it is fueling a second wave
About 4% of cases in the 24 hours to Wednesday at 1 pm there were reinfections.
In total, reinfections make up about 1% of all 1.5 million confirmed Covid cases in New Zealand.
(The actual percentage will be higher, though, because not everyone caught it Covid in the first Omicron wave would have tested or registered a positive case. If one of those people registers as a business now, it will look like they are for the first time when they aren’t.)
Since we were late at the ‘living with Covid’ reality of 2022, we can expect the reinfection rate to rise. It’s definitely higher overseas.
However, let’s stick to that number of 1.5 million for a moment. In reality, the actual number will be much higher – as much as half of us may have had the virus now†
This means two things:
- A lot of people have had Covid.
- There are still many sensitive people who have not yet contracted the virus and, like Professor Michael Plank has told before stuff† it’s those who haven’t had it who are probably at the greatest risk of infection in this wave.
While BA.5 is clearly capable of infecting humans again it is unlikely that the previous wave left us no protection†
Covid in the UK, for example, is still disproportionately hitting those who have so far sidestepped the virus.
As American journalist Ed Yong explains in a recent piece for: The Atlantic Ocean“About half of those in England who have been infected in the current wave” are for the first timeeven though they represent only 15% of the country’s population.”
He writes: “This clearly shows that while reinfections are a serious problem, the population still has some protection against catching even BA.5†
A pre-printed study from Qatar Released this week also suggests that having BA.2 provided significant cross-protection against BA.5.
Pre-Omicron infection, the study suggests, provides very little protection against BA.5, but notes that the “effectiveness of a previous infection against symptomatic BA.4/BA.5 reinfection was 76%.”
This is somewhat encouraging news. It supports the idea that BA.5 doesn’t just pass by all our existing immunity to that BA.2 attack.
But at the same time, 75% is not 100%, as Plank points out.
“75% immunity would mean that the risk of becoming reinfected is a quarter of the risk of becoming infected for the first time (according to BA.2) – so we would expect more first infections than reinfections, but there could still be quite a significant number of reinfections, and they will steadily increase as immunity wanes and the number of people not yet infected decreases.”
And on to case numbers
The seven-day moving average of Covid cases is around 10,000, but that only tells part of the story.
We start by looking at who has had Covid in New Zealand. As the table below shows, the first Omicron wave was concentrated in people under 50, particularly in teenagers and young adults.
The chart below shows the daily case totals by age group. You can see them increasing in all age groups, but the walks among the younger New Zealanders are not nearly as dramatic as the first time.
This doesn’t necessarily mean they won’t get infected either. They may simply not test or report positives.
As Professor Paul Hunter, professor of medicine at the University of East Anglia, recently told stuff: “We have seen in the UK that second infections are much less common in the daily dashboard numbers than primary infections, mainly because people are more likely to be sick enough to think they need a test.”
What is alarming, however, is that the number of cases in the oldest age groups is higher than during the March wave.
You can also see that the proportion of cases in the older age groups has increased.
Now you could point out that there were nothing but 800 or so Covid cases in 70-79 year olds on July 8 – no That far more than the 446 who tested positive on March 22.
However, given the number of hospital admissions in the age group 70+ sits at 3.9% vs 0.2% for those over 20, you can get a sense of how a small shift in the number of cases can add up to a significant burden on the health system.
And hospital admissions
As the chart below outlines, there has been a gradual increase in the average age of those hospitalized with Covid in the current wave.
Also alarming – and probably a consequence of who’s infected – is that the number of hospitalizations also seems to have risen slightly in recent weeks.
It is important to remember that these graphs show the percentage of people who have been hospitalized ‘with Covid’, which the Ministry of Health publishes daily.
Plank also suggests something else that may be contributing to the number of hospitalizations.
“People who have so far avoided infection, if their last vaccine doses were around January/February (like many) will now experience significant declines in immunity, which will likely contribute to hospital admissions as well.”
Those New Zealanders are vulnerable to any kind of Omicron infection.
Are more people dying than usual?
As Our world in data explainsexcess mortality is the number of deaths “from all causes during a crisis beyond what we would have expected under ‘normal’ circumstances”.
This provides a better measure of the true toll of Covid-19. In New Zealand, for example, about 1,600 have died from Covid. That doesn’t necessarily mean Covid killed themonly that they died within 28 days of testing positive.
ELLA BATES-HERMANS/Things
Covid-19 and flu have swept across the country at the same time this winter, affecting vulnerable health services.
Of those, 742 have been officially coded as a result of Covid-19, according to the Ministry of Health, although more than 200 are waiting to be classified. You can read more about how this works here†
A study published in the British medical journal last year showed a significant increase in the number of additional deaths in 2020 around the world. New Zealand, which kept Covid out, had a lower than expected overall death rate.
The table below gives us an indication of the overall death rate in New Zealand in 2022 – our first year of living with Covid-19.
As expected, death rates vary in different age groups. For example, the death rate in 0-4 year olds is usually lower than in 2021. But the death rate in 70-74 years is sometimes significant this year above the pre-pandemic average†
It’s only July, so we have to be careful not to read too much into this dataset right now.
What can I take with me from all this?
The overall conclusion, in our view, is that we see a higher rate of hospital admissions in a significantly older cohort.
The dilemma New Zealand may face is that this particularly vulnerable cohort of the population largely evaded BA.1 and BA.2 and may be less protected from BA.5.
This is especially troubling in the winter, where people are indoors and hospitals are under pressure from other respiratory illnesses. And the antibodies caused by their first booster will certainly have decreased.
This all touches on that somewhat bizarre Covid paradox – avoiding infection (particularly for the most vulnerable) is clearly a good thing, but at the same time infection, in combination with vaccinationcontributes to an immunity pool that protects the population.
Another thing to keep in mind in the coming weeks is that New Zealand now has its own unique immunity profile.
This makes it harder to look abroad for the next month and say, ‘Yeah, it’ll be fine, we’ll be just like those guys’.
We are on our own.