Updating on differences! Looking at numbers can indicate similarities even though there are many differences.
For the SARS CoV-2 virus – that causes Covid-19, there are similarities to the Flu – but these are different viruses all-together.(You can actually catch both the Flu Type A or B, and the SARS CoV-2 or Covid-19 at the same time)

Viruses are all around us, living in hosts and can spread at any time. (We should ask our scientists to stop going around looking for new viruses – such as what happened with SARS CoV-2, which was found in Horseshoe Bats in Caves near Wuhan – Fact – look it up in Virology journals!) (See below – about mutations – which if Humans have not been exposed before – there will be no ready immunity – thus, older people who can’t produce and fight the virus will tend to be affected the most)

In 1968 – the last major Flu Pandemic – the H3N2virus was a mutation (Which happens when the “live” virus splits and mutates based on its surroundings – (Thank you Darwin!) The H & N are the genes on a virus that causes it to act differently.
The H3N2 virus continues today as a seasonal virus, and we have vaccines shots to help control the spread. But this virus continues to go through “antigenic drift” which is small changes in the genes attached to the virus, which cause it to act differently when attaching to a host. (ie. animals and people)

In 1968 – there were over 1 million deaths worldwide (Only about 100,000 in the US. This virus has a strong affect on the over 65 population. Over 65 Population in 1968 – 19,134,000Over 65 Population in 2020 – 56,100,000 (Estimated due to Immigration numbers being uncertain) (An indicator of why there are more deaths today – than in 1968!)
Presently there are 4 types of Flu viruses (A&B are the seasonal flu – as these easily spread, Type C is mild, and Type D primarily affects cows!
Now due to the “antigenic drift” there are many possible known variations of Influenza (This is where mutations happen to the H & N – or hemagglutinin and neuraminidase) Meaning there can be up to 198 different combinations and 131 of them have been detected in nature! (ie. living!)
Now some differences – Influenza (Flu) and Covid-19 are both respiratory illnesses – but they are caused by different viruses!

The SARS-CoV was first reported in 2003 in Asia, It was contained to 33 different countries. There were no reports of SARS since 2004 until scientists discovered strains of SARS coronaviruses in Horseshoe bats in China

Studies completed and reported in 2006 – stated that it is possible for the newly discovered SARS coronaviruses may be transferable to humans and cause a epidemic – since humans did not show any evidence of having contact with the virus.

Note: The study stated that animal traders in Chinese food markets did show evidence of antibodies against the SARS CoV. This initial study indicated that at least 3 different animal species in the Shenzhen market were infected by coronaviruses that are closely related to SARS-CoV.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291347/

So – what does this tell us?*There are viruses on earth – which humans have not been in contact. These viruses will mutate based on their host. *These viruses will cause respiratory complications – which affect people who are older and do not have the potential immunity resistance, and people who have weaker immune systems for many different conditions. *That we must decide on the risks of scientific study. It would seem that if a SARS type virus were found by science – one that humans have not been in contact with- that a vaccine (or semblance of a vaccine) be created immediately for future duplication and use if the virus is released to humans.

Here is the potential scenario that created our current pandemic.Since 2003, scientists have been studying SARS and coronaviruses. Mostly in Bats found throughout Asia. (Poon, 2003; Woo, 2004) – In a study of 309 individual bats from 13 different species in 20 different locations – 37 bats had a coronavirus. But, there were 8 different types – 6 were novel. (ie. new!) What was found – different bat species in different locations had different coronaviruses. Scientists decided (WHO) to try and discover which bat contained the SARS-CoV strain that could cause pandemics. (This was a mission of the new virology lab in Wuhan.) Money from round the world went to this program.

Since the Horseshoe bat was the most likely bat that was able to transfer the SARS-CoV to others – it was to be captured and studied. The lab contracted with animal handlers to provide large numbers of Horseshoe bats for the lab experiments. (These bats contained the SARS-CoV!!)

When funding was cut – WHO dropped the research on potential SARS pandemic studies. Thus, the animal handlers who were capturing horseshoe bats no longer had an income. But this did not stop them from taking their captured bats and selling them to the Chinese live animal Markets. Thus, introducing live Bats with SARS-CoV – to the human population. There are 10 animals proven to be susceptible to infection by SARS-CoV – all of which were available in the Chinese Live Animal markets. (And prevalent in these markets are Rats – which are also susceptible to SARS-CoV.

Does this information help us stop the spread in Humans? – No

Can a vaccine be used to stop the spread – YesWill this virus continue to affect humans in the future – Yes

And, – there will be more viruses for which we can only hope scientists find immunology – rather than just study how they spread!