Covid-19: What is the difference between the flu and covid?

	Covid-19
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Covid-19: What is the difference between the flu and covid?

The virus of covid, technically called "SARS-CoV-2" belongs to the family of coronaviruses. There are hundreds of coronaviruses, most of which circulate among such animals as pigs, camels, bats and cats. RNA viruses are classified into three orders, one of which is Nidovirales, which is further classified into four families, one of which is the Coronaviridae, which is further divided into two subfamilies, one of which is Coronavirinae, i.e. coronaviruses. There are four main sub-groupings of coronaviruses, known as alpha, beta, gamma, and delta. The two deadliest coronaviruses, SARS and MERS, are both beta, and this one is also beta.
The flu (or influenza) viruses are not coronaviruses but, like coronaviruses, they are RNA viruses, but they belong to a different family of viruses (Orthomyxoviridae, which belongs to the category Articulavirales). While the covid virus and the flu virus are both made of RNA, they are distant cousins and their genomes are quite different. What they have in common is that they both attach to living cells via "surface proteins". The surface protein (called "spike protein") of the covid virus binds with a receptor of the cell (ACE2) and then injects its RNA into the cell and uses the cell's own machinery to replicate its RNA, i.e. itself. So the hijacked cell starts making copies of the covid virus and these copies infect other cells and use their machinery to make more copies. Influenza viruses use a different kind of surface protein (in fact, two of them) to achieve the same goal of hijacking cells and using them to replicate themselves (instead of ACE2 they bind to sialic acid). The fact that a virus is multiplying inside your body doesn't necessarily mean that you will get "sick": your immune system might destroy the virus before it causes damages to organs like the lungs, and you'll never know that you had it.
Both the flu and the covid viruses are spread via droplets that are released from an infected person's nose or mouth. It is very likely that the virus is also on the hands of the infected person so shaking hands or touching objects that have been touched by infected people are also a way to get infected. We know that the flu virus can remain infectious on surfaces for up to two days. We don't know yet for how long the covid virus can "survive" on surfaces, but one can guess at least two days.
Both covid and the flu can be transmitted by asymptomatic individuals, individuals who are not sick yet and maybe never get sick.
The covid virus is only one-year old (young) and we know little about his ability to mutate. On the other hand, we know that its cousin the influenza virus is constantly mutating, and that's why we don't have a universally effective flu vaccine and every year we need a new vaccine against the flu. The rule of thumb is: the higher the number of infected people the more likely that the virus mutates.
The flu virus is more contagious in cold weather. We don't really know why. Some speculate that the flu virus lasts longer in cold weather, and therefore you're more likely to be exposed to someone's flu virus, and some speculate that, quite simply, we spend more time indoors when the weather is cold. The role of vitamin D (which mostly comes from sunshine) is also a factor.
SARS-CoV-2 spread in the summer as well as in the winter. It doesn't appear like the temperature makes a difference.
Both the covid and flu viruses cause similar symptoms: fever, cough, shortness of breath, sore throat, runny nose, etc. Both may cause pneumonia and worse. So the symptoms lone cannot tell you if you have the flu or covid.
See also:
Back to FAQ/ Q&A about Covid-19,
Data on Covid-19 and selected sources,
Covid-19: How it may change the World,
The Clown & the Virus,
The Clown & the Virus - Part 2,
Trump's Virus,
Sinophobia & Covid-19,
Sinophobia & Covid-19 in US Media,
Was covid-19 made in the USA? in China? TM, ®, Copyright © 2020 Piero Scaruffi All rights reserved.
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