By now, readers will be familiar with the single strongest argument against Ireland’s impending level five lockdown: Cases are rising, yes, but hospitalisations, and deaths, remain low, notwithstanding the thirteen fatalities reported yesterday.

Is the low number of deaths and hospitalisations, as some argue, a glitch? Or is it part of a wider pattern that’s being replicated across the globe?

The answer to that is becoming clearer: Across the world, the second wave of covid is far less deadly. And now we have the studies to prove it, via NPR:

Two new peer-reviewed studies are showing a sharp drop in mortality among hospitalized COVID-19 patients. The drop is seen in all groups, including older patients and those with underlying conditions, suggesting that physicians are getting better at helping patients survive their illness.

We find that the death rate has gone down substantially,” says Leora Horwitz, a doctor who studies population health at New York University’s Grossman School of Medicine and an author on one of the studies, which looked at thousands of patients from March to August.

The study, which was of a single health system, finds that mortality has dropped among hospitalized patients by 18 percentage points since the pandemic began. Patients in the study had a 25.6% chance of dying at the start of the pandemic; they now have a 7.6% chance.

That’s very significant: In April, you had a one in four chance of dying if you ended up in ICU. Now, it’s down to about one in twelve.

One in twelve is still very high, of course – much higher than the flu, and far to high for my personal comfort, were I faced with those odds. But it’s still much better than the situation in the Spring.

And it’s showing up in the data, too. Look at these numbers from the US on cases versus deaths:

Now the obvious question here is “why?” – and to that, there are a few possible answers. One answer, and perhaps the most intuitive one, is that the death rate hasn’t changed at all, but that the changing figure is a result of more testing. Under this theory, in the spring, we had an absolutely enormous “hidden pandemic”, where only those with symptoms were getting tested, and as a result, the death rate looked much higher than it actually was.

But that doesn’t really make sense – because death rates for those in hospital have fallen. If you were sick enough to be in hospital in the spring, and you’re sick enough to be in hospital today, then the number of tests of asymptomatic people is sort of irrelevant. The number of people in hospital who are dying is down, which suggests an other explanation.

Is it just simply a function of doctors getting better at treating Covid? More from NPR:

“The people who are getting hospitalized now tend to be much younger, tend to have fewer other diseases and tend to be less frail than people who were hospitalized in the early days of the epidemic,” Horwitz says.

So have death rates dropped because of improvements in treatments? Or is it because of the change in who’s getting sick?

To find out, Horwitz and her colleagues looked at more than 5,000 hospitalizations in the NYU Langone Health system between March and August. They adjusted for factors including age and other diseases, such as diabetes, to rule out the possibility that the numbers had dropped only because younger, healthier people were getting diagnosed. They found that death rates dropped for all groups, even older patients by 18 percentage points on average….

Doctors around the country say that they’re doing a lot of things differently in the fight against COVID-19 and that treatment is improving. “In March and April, you got put on a breathing machine, and we asked your family if they wanted to enroll you into some different trials we were participating in, and we hoped for the best,” says Khalilah Gates, a critical care pulmonologist at Northwestern Memorial Hospital in Chicago. “Six plus months into this, we kind of have a rhythm, and so it has become an everyday standard patient for us at this point in time.”

Doctors have gotten better at quickly recognizing when COVID-19 patients are at risk of experiencing blood clots or debilitating “cytokine storms,” where the body’s immune system turns on itself, says Amesh Adalja, an infectious disease, critical care and emergency medicine physician who works at the Johns Hopkins Center for Health Security.

All of that points strongly to the “improving treatment” thesis.

But what it does not explain is why hospitalisations themselves have fallen. Sure, we might be better at treating people in hospitals, but why are so many fewer people going to hospital in the first place?

There’s no real answer for that, but there are two reasonable theories: One is that the age profile of the infected has sharply shifted towards the young. In Ireland, for example, nearly half of all new cases recently are in the 18-44 age group, where the risk of a severe illness is much lower.

The second theory is that the virus itself has become much more mild: If you subscribe to the theory of evolution, as we all should, then you’ll know that viruses that kill their hosts have fewer opportunities to spread. One reason the common cold is so effective is that it’s just a nuisance. Ebola, on the other hand, which kills half of its hosts, tends to get fewer chances to infect people. The virus, in plain terms, might be copping itself on, a bit.

Anyway, what’s indisputable is that deaths and hospitalisations are way, way, down across the globe. Whatever the reasons, we are not dealing with the same virus we were dealing with in the spring. So why are we so determined to use the exact same response, against a different enemy?