The occurrence of a new strain of SARS-CoV-2 cannot be ruled out. Therefore. this study seeks to investigate the possible effects of a hypothetical imperfect anti-COVID-19 vaccine on the control of not only the first variant of SARS-CoV-2 but also the second (new) variant of SARS-CoV-2. We further examine the rates r and a. https://burgaers.shop/product-category/travel-mug/