Abstract
Vaccination is an important means to fight against the spread of the SARS-CoV-2 virus and its variants. In this work, we propose a general susceptible-vaccinated-exposed-infected-hospitalized-removed (SVEIHR) model and derive its basic and effective reproduction numbers. We set Hong Kong as an example and calculate conditions of herd immunity for multiple vaccines and disease variants. The model shows how the number of confirmed COVID-19 cases in Hong Kong during the second and third waves of the COVID-19 pandemic would have been reduced if vaccination were available then. We then investigate the relationships between various model parameters and the cumulative number of hospitalized COVID-19 cases in Hong Kong for the ancestral, Delta, and Omicron strains. Numerical results demonstrate that the static herd immunity threshold corresponds to one percent of the population requiring hospitalization or isolation at some point in time. We also demonstrate that when the vaccination rate is high, the initial proportion of vaccinated individuals can be lowered while still maintaining the same proportion of cumulative hospitalized/isolated individuals.
Keywords: COVID-19; Delta variant; Omicron variant; SVEIHR model; compartmental model; vaccination.
【저자키워드】 COVID-19, delta variant, vaccination., Omicron variant, compartmental model, SVEIHR model, 【초록키워드】 Vaccine, vaccination, Immunity, Hospitalization, COVID-19 pandemic, Delta, SARS-CoV-2 virus, omicron, delta variant, variants, Spread, herd immunity, Isolation, Omicron variant, compartmental model, Hong Kong, disease, Strains, Herd immunity threshold, vaccinated individuals, reproduction numbers, cumulative, vaccinated individual, parameter, hospitalized COVID-19, vaccination rate, confirmed COVID-19 case, effective, initial, example, proportion, reduced, condition, individuals, calculate, the SARS-CoV-2 virus, 【제목키워드】 Delta, omicron, Impact, modeling,