Migrating from animals to humans, as documented in the following.
Well yes, scientists have falsified this hypothesis in history, and documented flues (from birds and swine to humans), and other viruses that migrate from animals to humans.
Cross-Species Virus Transmission and the Emergence of New Epidemic Diseases
Cross-Species Virus Transmission and the Emergence of New Epidemic Diseases
Colin R. Parrish,1,*
Edward C. Holmes,2
David M. Morens,3
Eun-Chung Park,4
Donald S. Burke,5
Charles H. Calisher,6
Catherine A. Laughlin,4
Linda J. Saif,7 and
Peter Daszak8
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ABSTRACT
Summary: Host range is a viral property reflecting natural hosts that are infected either as part of a principal transmission cycle or, less commonly, as “spillover” infections into alternative hosts. Rarely, viruses gain the ability to spread efficiently within a new host that was not previously exposed or susceptible. These transfers involve either increased exposure or the acquisition of variations that allow them to overcome barriers to infection of the new hosts. In these cases, devastating outbreaks can result. Steps involved in transfers of viruses to new hosts include contact between the virus and the host, infection of an initial individual leading to amplification and an outbreak, and the generation within the original or new host of viral variants that have the ability to spread efficiently between individuals in populations of the new host. Here we review what is known about host switching leading to viral emergence from known examples, considering the evolutionary mechanisms, virus-host interactions, host range barriers to infection, and processes that allow efficient host-to-host transmission in the new host population.
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INTRODUCTION
Newly emerging viral diseases are major threats to public health. In particular, viruses from wildlife hosts have caused such emerging high-impact diseases as severe acute respiratory syndrome (SARS), Ebola fever, and influenza in humans. The emergence of these and many other human diseases occurred when an established animal virus switched hosts into humans and was subsequently transmitted within human populations, while host transfers between different animal hosts lead to the analogous emergence of epizootic diseases (Table
(Table1).1). The importance of viral host switching is underscored by the recent avian epizootics of high-pathogenicity strains of H5N1 influenza A, in which hundreds of “spillover” human cases and deaths have been documented. Epidemiological data suggest that the toll on human populations would be enormous if the H5N1 virus acquired efficient human-to-human transmissibility while retaining high human pathogenicity (
25,
83). Considered an archetypal host-switching virus for its ability to infect a wide range of avian and mammalian species and for causing frequent zoonotic infections and periodic human pandemic transfers (Fig.
(Fig.11 and Table
Table2),2), the actual or threatened emergence of a new influenza A virus is a cause for alarm. Fortunately for us, most viral host transfers to infect the new hosts cause only single infections or limited outbreaks, and it is rare for a virus to cause an epidemic in a new host.
If he is willing to consult scientist and medical authorities like Obama did when he faced a pandemic, of course, he can. Based on his admission that he knew the dangerous nature of COVID-19, and lied to the American public he did know a great deal about COVID-19.