Abstract
A second deadlier wave of COVID-19 and the causes of the recent public health collapse of Manaus are compared with the Spanish flu events in that city, and Brazil. Historic sanitarian problems, and its hub position in the Brazilian airway network are combined drivers of deadly events related to COVID-19. These drivers were amplified by misleading governance, highly transmissible variants, and relaxation of social distancing. Several of these same factors may also have contributed to the dramatically severe outbreak of H1N1 in 1918, which caused the death of 10% of the population in seven months. We modelled Manaus parameters for the present pandemic and confirmed that lack of a proper social distancing might select the most transmissible variants. We succeeded to reproduce a first severe wave followed by a second stronger wave. The model also predicted that outbreaks may last for up to five and half years, slowing down gradually before the disease disappear. We validated the model by adjusting it to the Spanish Flu data for the city, and confirmed the pattern experienced by that time, of a first stronger wave in October-November 1918, followed by a second less intense wave in February-March 1919.
Highlights
Historical investigations and mathematical predictive models are methods to search out solutions for upcoming problems
Nine out of the 27 Brazilian States displayed more than 90% of occupation of intensive care units, and 18 States exhibited occupation above 80%, according to the Fundação Instituto Oswaldo Cruz FIOCRUZ report (OBSERVATÓRIO COVID-19 2021)
We explored the combined effects of a soft social isolation, which is currently applied to some Brazilian cities, and the appearance of new more transmissible variants, using Manaus parameters
Summary
Historical investigations and mathematical predictive models are methods to search out solutions for upcoming problems. We assumed in the SIR model that immunity was retained by three months, to simulate the fact that this influenza virus mutated much faster than coronavirus (Day et al 2020), and that the city may have been hit by various new variants from Europe since the onset of Spanish flu pandemic (Schwarcz & Starling 2020). Due to the full shifting of the original strain by new variants, the β-infection rate was permanently higher after the second wave than it was in the beginning of the pandemics
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