Infectious Disease Commonly used vaccines for influenza are trivalent and con- t
ID: 3272862 • Letter: I
Question
Infectious Disease Commonly used vaccines for influenza are trivalent and con- tain only one type of influenza B vrus. They may be ineffec- tive against other types of influenza B virus. A randomized clinical trial was performed among children 3 to 8 years of age in 8 countries. Children received either a quadrivalent vaccine (alv) that had more than one influenza B virus or a trivalent Hepatitis A vaccine (control) (Jain, et al., [9]. New England Journal of Medicine 2013: 369(26): 2481-2491). An attack rate (i.e.,90 of children who developed influenza) starting 14 days after vaccination until the end of the study was computed for each vaccine group, stratified by age. The following data were reported: 3.28 Suppose 3 children in a village ages 3, 5, and 7 are vaccinated with the QlV vaccine. What is the probability that at least one child among the 3 will get influenza?Explanation / Answer
From table the probability of getting influenza is
P(age 3 and get influenza) = 0.0378
P(age 5 and get influenza) = 0.0170
P(age 7 and get influenza) = 0.0170
The probability that neither of them get influenza is
P(none of them get influenza) = [ 1 - P(age 3 and get influenza) ][ 1 - P(age 5 and get influenza) ][ 1 - P(age 7 and get influenza) ] =[1 - 0.0378][1 - 0.0170][1 - 0.0170] = 0.92976
So the probability that at least one of them get influenza is
P(at least none of them get influenza)=1- P(none of them get influenza) =1 - 0.92976 = 0.07024