It’s still hard to predict who will die from Covid-19

Genetics may influence susceptibility to severe infection.
Image: Francesca Volpi/Bloomberg

In every epidemic, some die, others become ill and recover, and the luckiest live through infection without symptoms. In today’s pandemic, we are seeing this play out before our eyes. Although the initial epidemiological data show that Covid-19 is more severe in older people, men and those with pre-existing conditions such as heart and lung disease, not everyone with severe disease has these risk factors. And not everyone at risk has the same symptoms, prognosis or outcome.

Why do people manifest such differences? And why is it not possible to predict an individual’s experience? To address this complex question, it is important to first get our terminology right. “Infection” means acquisition of the coronavirus after exposure to it. Infection is not synonymous with exposure — or with disease. Disease is a clinical state associated with cough, fever and other symptoms that ranges from mild to severe. These symptoms arise from damage to tissues and the immune system. Death occurs when there is so much damage that the body cannot maintain blood oxygenation and other necessary functions.

In past epidemics, death and survival were attributed to providence or fortune. Modern medicine and science provide a better understanding of why infection can lead to such different outcomes. Among individuals in the same risk group — the same age, say — differences in infection outcome can result from five different variables outside their control.

The first of these is microbial dosage or inoculum, the number of viral particles that cause infection. Small numbers of viral particles are more likely to be contained effectively by the body’s defences. Then, infection may cause no symptoms or only mild disease. In contrast, a large number of particles can lead to increased viral growth, overwhelming the immune system and causing more severe disease.

Genetics may also influence susceptibility to severe infection. Viruses often gain access to host cells via surface proteins, which vary in presence and nature from person to person. Someone with no such surface proteins may be resistant to infection. In the case of HIV, for example, some people lack the receptors needed for viral infection and are not susceptible to the virus.

A third variable that influences infection outcome is the route by which a virus enters the body. It’s possible that virus inhaled in the form of aerosolised droplets triggers different immune defenses than does virus acquired by touching contaminated surfaces and then touching one’s face. The nose and the lung differ in local defenses, so the route of infection could significantly affect the outcome.

The fourth variable is the strength of the coronavirus itself. Viruses differ in virulence — their capacity to damage host tissues or immunity — even when they are all the same species. This is why flu seasons vary in severity from year to year. The varieties of a virus such as coronavirus differ depending on small genetic characteristics and how these affect the interaction with human hosts. As the coronavirus spreads from person to person, it may undergo unique changes in its genetic structure that enhance or attenuate its capacity to do harm. Strains that are more virulent could lead to more severe disease.

Finally, people’s immune status — especially their history of prior infectious diseases — crucially determines how they respond to a new infection. The immune system remembers previous encounters with microbes, and that affects how it fights and responds to new ones. In the case of dengue, infection with one type of the virus can make the individual more susceptible to infection with a different type of the same virus. In other situations, a recent infection with a virus can affect susceptibility to an unrelated new infection. For example, having had the flu before coronavirus infection could change the course of Covid-19 disease in unpredictable ways. When a person’s immune system has no memory of an infectious agent, it may be unable to rapidly respond, and this may allow the invader to escape detection, giving it more time to cause damage.

Taken together, these variables create a complex picture. The amount of virus, our genes, the route of infection, the variety of the virus and our immunological history combine to produce outcomes ranging from asymptomatic infection to death. And because these parameters can vary so much from infected person to infected person, it’s impossible to predict who will live and who will die. Therefore, despite accumulating evidence that most who acquire the coronavirus will not develop severe disease, the uncertainty of who is at grave risk enhances the pandemic’s terror.

In this regard, today’s situation is similar to past pandemics in which the matter of who would live and who would die was also mysterious — and led people to attribute outcomes to fortune or supernatural intervention. However, Covid-19 is different than the 1918 flu, in that today a robust scientific establishment can quickly analyse what’s happening and help figure out how best to prevent and treat infections. Science is humanity’s lifeline. In the days ahead, physicians, scientists, epidemiologists and many more will work hard to understand individual susceptibility to coronavirus. The Covid-19 pandemic will teach us a great deal of new science that will make us better prepared for the next outbreak.

© 2020 Bloomberg

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“today’s situation is similar to past pandemics”

This virus is the first with a significant probability that it was made by some imbecile in a lab, some IYI researcher, for who knows what reason…

Don’t spread false rumours.

On TV, history channel, a past world history named Vietnam, the war.
Unbelievable, but true. This virus Corona on hand should have been the perfect tool to get wanted. If I notice that, lab war boys are miles ahead in creating. Remember aids falling on humanity? From that moment on all barriers preventing inventing disappeared. With Bill Gates leading and funding. No rumor, but fact.

Yes unthinkable mankind! Yes and existence of bio weapons are false rumors belonging to Tom Cruise movies, no? Oh Griet, grow up.

I work in labs where GM organisms are made and used, lab made pandemic is totally plausible..Accident sure, maybe not bioweapon.

Check what Czech virologist Dr Sona Pekova said on national TV a few days ago.

But he keep drinking WHO cool-aid if it makes you feel good.

grow up..
conspiracy theories and hollywood movies at the end all have waivers to say they are fiction.

Whilst the C-19 is evidently rampant there is concern that the death rate in the UK is not more than the usual (the related information is actually made available in the UK, but not in the propaganda media).
We all need to be a little more skeptical about the value of the lockdown because there is evidently no impact on the usual death rate seen so far.
Ref: https://youtu.be/rNPSG3mHGkE
But the death of the economy is far from normal and will most likely result in far more suffering than the virus itself.

The government has ordered that only 20 will die of it. The rest will be of natural causes.

‘Todays situation is similar to past pandemics’

NO IT IS NOT! NOT EVEN CLOSE.

It does not even deserve to be called a dangerous pandemic. The whole world and the literally one in the same main news channels, with the running doomsday counter somewhere on the screen, with which they and the world has become obsessed, regarding 2 facts, daily new infections and daily new deaths are a joke.

Do not get me wrong i am not belittling those that have lost loved ones, or those that have suffered and recovered, nor those suffering or yet to contract the disease. But the numbers just do not warrant the attention, coverage nor hype. In fact this whole Covid 19 is very fishy. Let us have a look at those figures – where are we today i have not checked yet but around 1,8 million cases and 95k deaths (NO THAT IS NOT INE ONE COUNTRY, that is in 188 COUNTRIES yes the WHOLE WORLD) and this has been in the world for 5 months already, if we exclude China we can argue it has been with us for nearly 3 months, or about half of a typical flu season.

Some context in 2018/19 flu season in the USA alone, yes one country, they had 61,000 flu deaths and over 45 million cases of flu. Of these about – it was estimated that around 10 million or so hospital visits were required. Why was CNN or NBC or SKY not running a counter on the screen 2 years ago when this happened as it was clearly catastrophic – not! In 2013/2014 in the UK yes one country again, 28,335 people died of the flu – no counter running on media either. I have not selected the worst flu seasons ever just 2 different ones, this is available on the relevant government websites. The fact is these are just 2 countries that never warranted any TV time at the time. What about the other 187 countries in both those flu seasons, what were the numbers then all added together.

My point is USA has an average flu season in the last 55 years between 20,000 deaths in a mild season and in a bad one they come closer to 100,000 deaths. Take the worst flu season in the last 55 years which was 1968 – 3 million people died around the world in 6 months, in an estimated total number of cases of close 800 million+. No we did not shut down for business and the media did cover it, but with nothing more severe than ‘we are having a very bad flu season this winter’ headlines.

If this COVID 19 global pretend crisis situation, is similar to past pandemics, then we need to question the people we voted into power. As this pandemic then is the MILDEST PANDEMIC we have had in 55 years as in 56th place in a row, including the one that just ended on the 31st March 2020 for normal flu. The obvious question being why have you put us in police state over what amounts to nothing and unemployed millions under this pretence?

Imagine a normal flu season tracked in the same manner, numbers tracked cases and deaths, now imagine we did that annually for context. The fact that we have not is because all flu seasons including 1968 did not even cause a blip on the global mortality rate nor that in any specific country, Covid 19 will not even come close. All flu seasons start slow and then they have the ugly ramp up hockey stick part, they plateau then drop off a cliff during their typically 6mth life span. Globally in an average FLU SEASON, we have around 320 – 400 million flu cases and around 650k to 1m deaths – sorry but as of today we are on not even on 2 million covid 19 cases and less than 100k deaths and we are arguably half way through Covid 19 season or will be in the next week or 2, what we are seeing is a very very very mild secondary flu season at worst. SO why all the hysteria?

PS – who will die is not a mystery. We know that 98% of all covid 19 deaths will be of an elderly age of 70+ and with an underlying condition or 3. The only mystery is why the 2% are taken with no underlying condition and likely for genetic reasons our science has not advanced far enough to recognise yet – but this number is 6%+ in normal flu. Something is not right in the state of Denmark – as for RSA – WOW! – 1900 cases and 18 deaths and 2 more weeks of shut down …

Romulus is an imbecile

for comparing data from a “flue” to COVID with the whole world locked in.

COVID death rate is at minimum x20 more and more infections.

That is not to speak of all the unknown effects on infected that survive..

The most insane overreaction ever. The only ones that should be locked up are the politicians using this opportunity to control and subvert more. Politicians will never let an opportunity like this pass – watch for regulations being pushed through to remove more rights and control more.

We are all being told to wreck our economy for 30 lives lost. Pure insanity. The old and infirm can stay home the rest of us should function normally and keep this spluttering economy from falling in a heap.

Shows you what the media can achieve, and every one buys in, causing major panic, blame, economic disaster and turmoil. Might be one difference no cure yet.

I notice that the fact that men are more susceptible to Covid-19, than women, is conveniently brushed over. Perhaps Mother Nature just doesn’t understand that we are all supposed to be equal. It’s so unfair! Men, at the very least, should march and demand a commission of inquiry, burn a Jocky, or lay a charge against Mother Nature for discrimination, until such time as she spreads the disease equally between men and women – obviously all done for the sake of equality.

End of comments.

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