Abstract

AHMED AZIZ, Kamran Mahmood; OTHMAN, Abdullah; ALQAHTANI, Waleed Abdullah  and  AZHAR, Sumaiya. Factors affecting SARS-CoV-2 (COVID-19) pandemic, including zoonotic, human transmission and chain of infection. Reducing public health risk by serum antibody testing, avoiding screening in unhygienic places and false PCR reporting. A scientific review. Iberoam J Med [online]. 2021, vol.3, n.2, pp.138-160.  Epub Dec 25, 2023. ISSN 2695-5075.  https://dx.doi.org/10.5281/zenodo.4599718.

During December 2019, a rapid increase in the number of SARS-CoV-2 (COVID-19) cases was reported worldwide. We investigated several factors for rapid increase in SARS-COV-2. Genomic sequence reveals that domestic and wild animals were likely ancestors and zoonotic source for SARS-CoVs, MERS-CoVs, and SARS-CoV-2; these viruses replicated in animals and humans during past several decades, exhibiting diverse mutations and self-limiting diseases except during outbreaks. SARS-CoV-2 has been retrospectively isolated in different studies in August 2019, several months before Wuhan reported. Hence, there is a possibility that viruses went undetected and infecting sub-clinically, in past several years, and SARS-CoV-2 antigens and neutralizing antibodies may have been present in humans since years. All SARS-CoVs are basically respiratory viruses, spread by droplets, hence droplet precautions are essential. Furthermore, silent phase of transmission (asymptomatic/subclinical) can be beneficial for humans. Lack of symptoms eventually lessen virus transmission and reduce the pathogen's long-term survival and provide strong humoral herd immunity (with sropositivity and diverse antibodies) up to several years and during epidemics. RT-PCR has low sensitivity and specificity, carries a high risk of handling live virus antigens, and requires difficult protocols. As viral load also sharply declines after few days of onset of infection, this technique might overlook infection. Furthermore, SARS-CoV-2 infection may be present in blood when oropharyngeal swabs are negative by RT-PCR. Conversely, antibodies against SARS-CoVs develop robustly in by reduced amount of antigens and ELISA for diagnosing antibodies demonstrates 100% specificity and 100% sensitivity, even in clinically asymptomatic individuals. These antibodies can be used for serologic surveys, monitoring and screening. Furthermore, screening tests for SARS-COV-2 should be avoided in unhygienic public places by nasopharyngeal swabs, which carry a high risk of further transmission, co-infection or super-infection. If above mentioned factors and Infection control policy is followed, SARS-CoV-2 pandemic can be controlled effectively.

Keywords : SARS-CoV-2; RT-PCR; Antibody; Zoonotic; Animal transmission; Genomics; Asymptomatic fraction; Herd immunity.

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