COVID-19(50) SARS-CoV-2(28) mathematical model(17) Intervention(12) Epidemic(11) Infection(11) parameter(11) Effect(10) individual(10) develop(10) social distancing(9) outbreak(9) Epidemics(9) mathematical(8) vaccination(8) diffusion(8) Mathematical modelling(8) immune response(8) Transmission(7) antibody(7) SARS-CoV-2 variant(7) Contact(7) produced(7) Analysis(7) Optimal control(6) Epidemiology(6) Effectiveness(6) maintain(6) individuals(6) Non-pharmaceutical interventions(6)