Table 2 Estimated effectiveness of the pandemic influenza vaccine during the main wave of the influenza pandemic in Norway.

Vaccinated population

No of cases

3

40

45

31

21

7

5

1

1

3

Population

32,766

266,276

501,087

697,952

873,561

1,105,676

1,397,413

1,675,256

1,891,882

1,891,654

Incidence(per 100,000)

9.16

15.02

8.98

4.44

2.40

0.63

0.36

0.06

0.05

0.16

Unvaccinated population

No of cases

2683

2540

1,581

854

449

182

80

33

16

12

Population

4,811,608

4,575,412

4,338,021

4,139,530

3,963,036

3,730,451

3,438,525

3,160,597

2,943,937

2,919,148

Incidence(per 100,000)

55.76

55.51

36.45

20.63

11.33

4.88

2.33

1.04

0.54

0.41

Vaccine effectiveness

Point estimate

84%

73%

75%

78%

79%

87%

85%

94%

90%

62%

95% confidence interval

50%-95%

63%-80%

67%-82%

69%-85%

68%-86%

72%-99%

62%-94%

58%-99%

27%-99%

-34%-90%