Commonly used vaccines for influenza are trivalent and contain only one type of

ID: 3298986 • Letter: C

Question

Commonly used vaccines for influenza are trivalent and contain

only one type of influenza B virus. They may be ineffective

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 (QIV) 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.,% 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:

Suppose that 80% of 3–4-year-old children and 70% of

5–8-year-old children in a village are vaccinated with QIV

vaccine. Also assume that children who are not vaccinated

have twice the incidence of influenza as the control group

in Table 3.7.

3.29 What % of 3–4-year-old children in the village will get

influenza?

TABLE 3.7 Attack rate for influenza by age and treatment group OlV group Control group age 3-4 5-8 5.69% 5.15% 3.7896

% of 3 - 4 years old in the village that will get influenza

= 0.8*0.0378 + 0.2*0.0569

= 0.04162

= 4.162%

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