Subject(s)
COVID-19 , Selenium , Humans , Selenium/pharmacology , COVID-19 Vaccines , SARS-CoV-2 , Oxidation-ReductionABSTRACT
The COVID-19 pandemic caused multiple waves of mortality in South Africa, where three genetic variants of SARS-COV-2 and their ancestral strain dominated consecutively. State-of-the-art mathematical modeling approach was used to estimate the time-varying transmissibility of SARS-COV-2 and the relative transmissibility of Beta, Delta, and Omicron variants. The transmissibility of the three variants were about 73%, 87%, and 276% higher than their preceding variants. To the best of our knowledge, our model is the first simple model that can simulate multiple mortality waves and three variants' replacements in South Africa. The transmissibility of the Omicron variant is substantially higher than that of previous variants.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Pandemics , South AfricaABSTRACT
OBJECTIVE: The SARS-CoV-2 Omicron (B.1.1.529) variant has caused global concern. Previous studies have shown that the variant has enhanced immune evasion ability and transmissibility and reduced severity. METHODS: In this study, we developed a mathematical model with time-varying transmission rate, vaccination, and immune evasion. We fit the model to reported case and death data up to February 6, 2022 to estimate the transmissibility and infection fatality ratio of the Omicron variant in South Africa. RESULTS: We found that the high relative transmissibility of the Omicron variant was mainly due to its immune evasion ability, whereas its infection fatality rate substantially decreased by approximately 78.7% (95% confidence interval: 66.9%, 85.0%) with respect to previous variants. CONCLUSION: On the basis of data from South Africa and mathematical modeling, we found that the Omicron variant is highly transmissible but with significantly lower infection fatality rates than those of previous variants of SARS-CoV-2.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , South Africa/epidemiologyABSTRACT
There are 7 novel coronavirus known to infect humans, namely, HCoV-229 E, HCoV-OC43, HCoV-NL63,HCoV-HKU1, SARS-CoV-1, MERS-CoV and 2019 new coronavirus(SARS-CoV-2), among which three viruses can cause severe acute respiratory syndrome, but they have different characteristics. The pathogen of SARS and t COVID-19 belong to group B of coronaviridae and beta-coronavirus, and their receptors are ACE2, but they belong to two subtypes. MERS-CoV belonging to the same genus of beta-coronavirus belongs to group C, and its receptor is CD26(DPP4). Above three kinds of coronavirus causing human severe respiratory syndrome were compared and analyzed systematically in order to provide theoretical basis for prevention and control, diagnosis and treatment.