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Why the second wave of Covid-19 appears to be less lethal

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While coronavirus infections have been surging again across Europe since late summer, the chances of surviving the respiratory disease seem to have improved from the first phase of the outbreak.

The number of Covid-19 patients ill enough to go to hospital has risen less steeply — and mortality more slowly still, according to an FT analysis. Health services are not overwhelmed as they would have been if severe disease had followed infection in the way it did between March and April.

“In western Europe, pretty much every country including the UK is still seeing a much smaller per capita death rate in this second wave than in the first one during the spring,” said Mark Woolhouse, professor of infectious disease epidemiology at the University of Edinburgh.

The falling “case fatality rate” — deaths as a proportion of confirmed cases — can be explained partly by increased testing, which reveals more infections, and by the fact that a higher percentage of people with Covid-19 today are young and less likely to become severely ill than patients in the spring.

But even patients admitted to critical care are more likely to survive now than their counterparts earlier in the pandemic. Data from ICNARC, the UK Intensive Care National Audit and Research Centre, show that the proportion who died within 28 days of admission fell from 39 per cent in the months to August 31, to 27 per cent after September 1.

Chart showing share of patients who died, by number of days in critical care (%). Mortality rates in UK intensive care units are lower in the autumn than in the spring and summer

The increase in 28-day survival was most notable in patients under 70. It rose from 61 to 79 per cent among those aged 50 to 69, and from 82 to 91 per cent among under-fifties.

Improvements are being seen across a wide range of patients, including those with additional chronic health problems, and those with very low blood oxygen saturation levels, an indicator of particularly severe respiratory illness.

Chart showing 28-day in-hospital mortality rate (%) by admission date and selected patient characteristics. Covid-19 mortality rates in UK ICUs have halved among under-70s in the autumn

Paul Hunter, professor of medicine at the University of East Anglia, attributed about half of the improvement to the use of dexamethasone and other steroid medicines to reduce inflammation and damp down patients’ overactive immune systems.

“The rest is probably down to the experience of doctors and nurses learning how to treat patients,” he said. “We see this in any epidemic, when medics flail around for a bit as they discover what works best. With Ebola, for example, mortality rates fell during the epidemic in west Africa.”

Peter Openshaw, professor of experimental medicine at Imperial College London, has a similar explanation. “People have learnt many little tricks which, when added together, make a big difference over time.”

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For instance, clinicians are gaining a better sense of when to give patients blood thinners, when to put them on ventilators and when to place them in a prone position on their stomach to increase oxygen intake.

The age composition of Covid-19 hospital patients has also shifted, with over-sixties accounting for less than half of patients in August, down from 70 per cent in February, according to data compiled from 44 countries by ISARIC, the International Severe Acute Respiratory and Emerging Infection Consortium.

But improved hospital outcomes are not just the result of shifting patient demographics: in-hospital mortality among over-sixties halved from 50 per cent in early spring to 25 per cent in August.

Chart showing in-hospital mortality rate among patients aged 60+, by month of death or discharge

Nonetheless, interpreting trends in hospital mortality remains tricky, as there are many differences between the spring and autumn cohorts of patients beyond their age composition.

“It is extremely hard to compare the people who were hospitalised when it was incredibly difficult to even get a test and people were waiting a long time to go in and those today who are tested at the slightest sign of symptoms and get admitted much more easily,” said Gideon Meyerowitz-Katz, an epidemiologist at the University of Wollongong in Australia.

The number of people in hospital with Covid-19 is rising again across much of Europe, with occupancy levels already exceeding half of their spring peak in several countries particularly in eastern Europe. Current patient numbers in the Czech Republic are far higher than in March and April.

Chart showing patients in hospital with Covid-19 per 100,000 people; hospital admissions are rising again across most of Europe

In terms of mortality, Europe’s Covid-19 resurgence is proving less frantic than the original spring surge, with death rates climbing more slowly this time. Since deaths began rising again in late summer, it has taken one month on average for them to reach one death per million people. In March the same ascent took one week.

Chart showing 7-day rolling average of new deaths per million, by number of days since average exceeded 0.1 in same phase of outbreak; death rates are rising again across Europe, but at a much slower pace than in spring

Scientists also discuss more speculative reasons why Covid-19 may be becoming less lethal.

One is that people who become infected today receive lower doses of coronavirus than six months ago, for behavioural reasons including more cautious social interactions and wearing masks. In many respiratory infections, a smaller viral load tends to produce less severe disease though there is no direct evidence for Covid-19.

Another factor that is sometimes mentioned — and dismissed by most viral geneticists — is that the virus has mutated to become less virulent but perhaps more infectious.

“Scientists who have credibility on the genetics of virulence tell me that this has not changed yet,” said Prof Hunter, “but that doesn’t mean that it will not change eventually”.

A plausible theory, he added, was that two other previous coronaviruses could have jumped from animals into humans — “one in Tudor times and the other in Victorian times” — and caused epidemics with many deaths, which were regarded then as outbreaks of severe influenza. Their viral descendants still circulate among people today, causing symptoms no worse than a common cold.



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Analysis

Can plant-based milk beat conventional dairy?

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Plant-based milk brands are churning up the global dairy business, with a surge in sales, investment, and new products coming to market. The plant derived dairy trade is now worth an estimated $17bn worldwide.

Growing consumer demand has boosted investment. According to data firm Dealroom, venture capital funding across the plant-based dairy and egg sector has skyrocketed, from $64m in 2015 to $1.6bn in 2020.

The world’s biggest food company, Nestle, recently launched its first international plant-based dairy brand, a cow’s milk substitute made from yellow peas. Wonder will come in a variety of flavours, competing with established brands like Oatly oat-based milk. Founded in Sweden in the 1990s, that company is now valued at around $15bn. Demand for alternatives to soya, which once dominated the dairy free market, continues to escalate.

In the west, sales for other plant-based milks, including oat, cashew, coconut, hemp, and other seeds overtook soya back in 2014. Since then, they’ve raced ahead to be worth almost three times as much as soya products, with a combined projected value of more than $5bn in sales by 2022.

Advocates argue that plant-based production emits less greenhouse gas than cattle, making it the way forward to help feed the world and curb global warming. But dairy groups are fighting back with their own sustainability campaigns. And cow’s milk is hard to beat when it comes to naturally occurring nutrients, like protein, vitamins and minerals.

The average 100 millilitre glass of cow’s milk contains three grammes of protein, compared to 2.2 grammes in pea milk and just one gramme in oat-based substitutes.

Dairy producers have also won a legal bid, preventing vegan competitors in the EU from calling their products milk and yoghurt. Despite their growing popularity, plant-based brands are a long way from displacing conventional milk products. Their current $17bn turnover is still a drop in the pail, compared with the traditional cattle-based dairy trade, which is worth an estimated $650bn worldwide.



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'It’s more than sport – every day we are fighting for our rights to be equal’

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French pro basketball player and podcaster Diandra Tchatchouang on her role beyond the court



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Emily Dean on how allyship amplifies the female experience on film

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When I was six years old, I decided to be an artist. When I was 12, I decided to be a filmmaker. And instead of saying no, you can’t do that, or it’s not possible, my mum bought me a video camera.

After several years of working in the industry, I’m working with a female director for the first time. And it’s been such a gratifying experience. Women express leadership in different ways. Maybe you don’t have to be the loudest person in the room. But you can have great ideas.

And the best thing about being mentored by women and being a mentor to women is that make friends with women.

There’s something so powerful the women coming alongside other women, especially in a group setting. Because it means that you can and back each other up. You can support each other’s decisions, and you can amplify each other’s voices.

It’s about seeing yourself in your work. Seeing some part of yourself reflected is really gratifying. It’s also important that we speak up for female characters. I want to see girls and women on screen who have the whole cacophony of experience of what it’s like to be female.

I want to see their flaws. I want to feel their struggles. I want to see their joy. That is so important to making a character feel real. And it took me a little while to settle into myself and realise, if the characters I like to come up with are not your everyday run of the mill characters you see in animation, that’s fine. Because this is who I am.

When you walk into a story room, when you’re working on a film, you have to leave your ego at the door. I think that can be interpreted like keep your ego out of the work. But I’d also say for women who are maybe more shy that leaving your ego at the door means you walk in. And your job is to focus on what’s best for the story and for the film.

The story needs you. The film needs you, and it needs your best ideas. It won’t thrive unless you speak up.



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