How did COVID-19 jump the species barrier?

Question

I am not a medical professional. I also do not have enough knowledge on medicine or biology. But I have been wondering a lot about one question in particular for some time: How did COVID-19 jump the species barrier?

I searched for the topic online and came across this report from WHO published in February 2020. It states in the beginning:

The new COVID-19 is caused by the virus SARS-CoV-2. The most likely ecological reservoirs for SARS-CoV-2 are bats, but it is believed that the virus jumped the species barrier to humans from another intermediate animal host. This intermediate animal host could be a domestic food animal, a wild animal, or a domesticated wild animal which has not yet been identified.

This seems to indicate that the virus first jumped to an intermediate specifies, most likely to a domesticated species before it started affecting humans. What I am really interested in knowing is does this jump happen naturally and we are just unfortunate that it jumped at this specific time in history or, are there indications that this jump was accompanied by artificial means (i.e., through some artificial means of replicating an animal virus and designing it to be harmful for humans)?

I am only curious about this and just wanted some professional opinion. This question is only for purposes of a healthy and educative discussion and is by no means an attempt to create panic or spread false information and conspiracies. Thank you.

Answer 1

The transmission of a disease from an animal to humans is called zoonosis. And researchers have found out that COVID 19 was transmitted to humans via bats. These viruses enter into the human system via various ways:-

1. When an infected animal bites the human
2. When a human has cracked skin and comes in contact with potentially infectious fluids of animals such as blood, saliva, etc.

There maybe a role of an intermediate animal too in the transmission.

The two main questions, the answers to which show us how the virus transmits from bats to humans are:-

1. Can the virus reach the host cell?

A) In case of COVID 19, the fact that bats and even the predicted intermediate animal (pangolin) were being sold at the market in Wuhan shows that contact was present between the suspected animal and humans.

2. Can the virus bind to the receptors(gates) and enter the host cell in order to replicate?

A) Researches have found evidence that SARS CoV 2 virus binds to ACE 2(Angiotensin converting enzyme 2) receptors on the host cell. And this capability of the virus develops through mutations(changes in the genes) when they are in animals which are called reservoirs because they store these viruses.

And while it can be assumed that someone might have created this virus to make it harmful to humans, evidence suggests otherwise. I have added reference regarding the evidence about this point(ref 1). The explanation to this is very technical and goes to the molecular level. To explain it in simple terms, if you want to make a new virus, you need to take an old virus and the make changes in it to make it new. But evidence shows that the novel corona virus do not have a lot of similarity to the known existing viruses at the molecular level.

I hope this satisfies your curiosity .

References:-

1. https://www.sciencedaily.com/releases/2020/03/200317175442.htm

2. https://www.vox.com/science-and-health/2020/2/12/21133560/coronavirus-china-bats-pangolin-zoonotic-disease