3) The Oxford-AstraZeneca COVID viral vector vaccine is the primary COVID-19 vaccine used in the European Union. It requires two shots and achieves full immunization 22 days after the first shot. During the initial phase-III clinical trials in Fall 2020 there were 89 COVID cases out of the 8597 in the vaccinated group, compared to 248 cases out of the 8581 in the unvaccinated group (placebo vaccine). a) Calculate the risk of COVID infection in the vaccinated and unvaccinated groups. b) How many percentage points lower is the risk of COVID for those who took the vaccine in the study? Communicate the meaning of your answer in a sentence. c) What is the relative risk of COVID for the unvaccinated group? Communicate the meaning of your answer in a sentence. d) What is the percent decrease in COVID risk for the vaccinated group compared to the unvaccinated group (the vaccine efficacy)? Communicate the meaning of your answer in a sentence