A July 2020 article in the New England Journal of Medicine reports the results of a randomized trial designed to assess the efficacy of Hydroxychloroquine in preventing Covid-19 infection in persons exposed to others with Covid-19.

There were 821 subjects enrolled in this study.Of the 414 randomized to the treatment (Hydroxychloroquine) arm, 49 (11.8%) developed Covid (or probable Covid) within 14 days of randomization. Of the 407 randomized to the placebo arm, 58 (14.3%) developed Covid (or probable Covid) within 14 days of randomization.

A. Estimate, and report,a 95% confidence interval for the relative risk of 0.83?

B. Does the interval from item "A"include the null value for relative risks?

C. Based on the analyses youhave done in the previous questions for this exercise, how will the estimated odds ratio of developing Covid (or probable Covid) for the Hydroxchloroquine group compared to the place group compare to the value 1?

D. Based on the analyses youhave done in the previous questions for this exercise, will the 95% CI for the odds ratio of developing Covid (or probable Covid) for the Hydroxchloroquine group compared to the placebo group include the value 1.0?