Table 1.

Data characteristics, 2010–11 to 2016–17 influenza seasons.

Characteristic	Median	Minimum	Maximum
Vaccination measures
Vaccine effectiveness, %*	47.6	15.2	67.0
Vaccine coverage, %	55.0	28.4	70.1
Vaccination timing, %†	89.9	79.0	96.7
Month of vaccination, mean‡	3.5	3.4	4.0
Month of vaccination, SD	1.6	1.3	1.8
Skewness	1.1	0.8	1.7
Kurtosis	1.3	0.2	3.7
Illness measures
Infected, %	9.2	2.3	14.5
Month of onset, mean‡	6.7	5.8	7.9
Month of onset, SD	1.2	1.0	1.4
Skewness	−0.4	−1.7	0.9
Kurtosis	0.3	−0.6	3.9

Values were calculated from 35 data subsets defined by seven seasons and five age groups (6-months-4 years, 5–17 years, 18–49 years, 50–64 years, ≥65 years). Values were not weighted by population size.

Abbreviations: SD, standard deviation.

^*For most seasons, vaccine effectiveness was the same throughout the season for a given age group. However, in 2012–13 and 2014–15, vaccine effectiveness varied, being lower during August-February when A/H3N2 viruses predominated and higher in March-April when influenza B viruses predominated.

^†Percent of vaccine given before cases occurred (see Methods).

^‡Months were counted from August of each season (e.g., month 3 was October and month 6 was January of the following year).