Deaths, infections, and herd immunity in the COVID-19 pandemic: A comparative study of the strategies for disease containment implemented in Peru and the United Kingdom

Abstract Introduction: In light of the threat posed by the COVID-19 pandemic, most countries have implemented several containment and prevention measures to slow down the rapid spread of the disease. Objectives: To compare the COVID-19 pandemic containment strategies implemented in Peru [World Health Organization (WHO) - confinement and social distancing] and the United Kingdom [herd immunity (HI)] in terms of morbidity and mortality, and to simulate the implementation of HI in Peru during the initial stage of the pandemic. Materials and methods: Exploratory study with a simulation model based on official data obtained from both countries at the beginning of the pandemic. Mortality, case fatality, and infection rates documented within the first 55 days after the first COVID-19 case report in the United Kingdom and the start of the WHO-recommended containment and prevention strategy implementation in Peru were evaluated. Additionally, the impact of applying HI, according to WHO guidelines, as the initial strategy in Peru was simulated. The Paired-samples t-test was used to determine the differences between the two strategies at both stages of the study. Results: During the follow-up period, 15 034 and 33 931 COVID-19 cases were reported in the United Kingdom and Peru, respectively. The case fatality rate was higher in the United Kingdom (7.82% vs. 2.74%), while the cumulative mortality rate was higher in Peru (2.89 vs. 1.74x100 000 inhabitants p= 0.0001). Regarding the simulation, a minimum critical population of 60% (>19 million positive cases) was established for Peru to achieve HI, with 1 223 473.1 deaths and a hospitalization rate of 44 770x100 000 patients. Conclusions: During the follow-up period (55 days), the United Kingdom's strategy resulted in a higher case fatality rate, while the Peruvian strategy in over twice as many COVID-19 cases. The HI simulation strategy in Peru showed a sharp increase in all unfavorable indicators of the pandemic.