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Table 2 Risk of post-vaccinial encephalitis (P.V.E.) and death from primary smallpox vaccinations, Stratified by age and study, 1963–1968

From: Risks of serious complications and death from smallpox vaccination: A systematic review of the United States experience, 1963–1968

Age group and studies

Number vaccinated

P.V.E. No.

Deaths No.

Risk of complication per million (95% C.I.)a

Risk of death per million (95% C.I.)a

Case fatality risk per hundred (95% C.I.)a

Age <1

         

   Neff 1967a

654,000

1

0

1.5

(0.04, 8.5)

0.0

(0.0, 5.6)

0.0

(0.0, 97.5)

   Neff 1967b

31,000

1

0

32.3

(0.8, 180)

0.0

(0.0, 119)

0.0

(0.0, 97.5)

   Lane 1969

614,000

4

3

6.5

(1.8, 167)

4.9

(1.0, 14.3)

75.0

(19.4, 99.4)

   Lane 1970

17,000

3

1

176.5

(36.4, 515)

58.8

(1.5, 328)

33.3

(0.84, 90.6)

   Ratner 1970

1

0

0

n/c

n/c

n/c

n/c

n/a

n/a

   Neff 1972

32

0

0

n/c

n/c

n/c

n/c

n/a

n/a

   Summary

1,316,033

9

4

6.8

(3.1, 13.0)

3.0

(0.8, 7.8)

44.4

(13.7, 78.8)

Age 1 to 4

         

   Neff 1967a

2,973,000

2

1

0.7

(0.08, 2.4)

0.3

(0.008, 1.9)

50.0

(1.3, 98.7)

   Neff 1967b

142,000

0

0

0.0

(0.0, 26.0)

0.0

(0.0, 26.0)

n/a

n/a

   Lane 1969

2,733,000

6

0

2.2

(0.8, 4.8)

0.0

(0.0, 1.3)

0.0

(0.0, 45.9)

   Lane 1970

317,000

3

0

9.5

(2.0, 27.6)

0.0

(0.0, 11.6)

0.0

(0.0, 70.8)

   Ratner 1970

68,002

0

0

0.0

(0.0, 54.2)

0.0

(0.0, 54.2)

n/a

n/a

   Neff 1972

517

0

0

0.0

(0.0, 7110)

0.0

(0.0, 7110)

n/a

n/a

   Summary

6,233,519

11

1

1.8

(0.9, 3.2)

0.2

(0.004, 0.9)

9.1

(0.23, 41.3)

Age 5 to 19

         

   Neff 1967a

2,295,000

8

4

3.5

(1.5, 6.9)

1.7

(0.5, 4.5)

50.0

(15.7, 84.3)

   Neff 1967b

110,000

0

0

0.0

(0.0, 33.5)

0.0

(0.0, 33.5)

n/a

n/a

   Lane 1969

1,959,000

5

1

2.6

(0.8, 6.0)

0.5

(0.01, 2.8)

20.0

(0.50, 71.6)

   Lane 1970

229,000

2

0

8.7

(1.1, 31.5)

0.0

(0.0, 16.1)

0.0

(0.0, 84.2)

   Ratner 1970b

193,721

1

1

5.2

(0.1, 28.8)

5.2

(0.1, 28.8)

100.0

(2.5, 100)

   Summary

4,786,721

16

6

3.3

(1.9, 5.4)

1.2

(0.5, 2.7)

37.5

(15.2, 64.6)

Age 20 +

         

   Neff 1967a

317,000

1

0

3.2

(0.1, 17.6)

0.0

(0.0, 11.6)

0.0

(0.0, 97.5)

   Neff 1967b

15,000

0

0

0.0

(0.0, 246)

0.0

(0.0, 246)

n/a

n/a

   Lane 1969

288,000

1

0

3.5

(0.1, 19.3)

0.0

(0.0, 12.8)

0.0

(0.0, 97.5)

   Lane 1970

33,000

0

0

0.0

(0.0, 112)

0.0

(0.0, 112)

n/a

n/a

   Ratner 1970b

107,822

0

0

0.0

(0.0, 34.2)

0.0

(0.0, 34.2)

n/a

n/a

   Summary

760,822

2

0

2.6

(0.3, 9.5)

0.0

(0.0, 4.8)

0.0

(0.0, 84.2)

All agesc

         

   Neff 1967a

6,239,000

12

5

1.9

(0.2, 3.4)

0.8

(0.3, 1.9)

41.7

(15.2, 72.3)

   Neff 1967b

298,000

1

0

3.4

(0.1, 18.7)

0.0

(0.0, 12.2)

0.0

(0.0, 97.5)

   Lane 1969

5,594,000

16

4

2.9

(1.6, 4.6)

0.7

(0.2, 1.8)

25.0

(7.3, 52.4)

   Lane 1970

596,000

8

1

13.4

(5.8, 26.4)

1.7

(0.04, 9.3)

12.5

(0.3, 52.6)

   Mellin 1970

109,000

0

0

0.0

(0.0, 33.8)

0.0

(0.0, 33.8)

n/a

n/a

   Ratner 1970

369,546

1

1

2.7

(0.07, 15.1)

2.7

(0.1, 15.1)

100.0

(2.5, 100)

   Neff 1972

549

0

0

0.0

(0.0, 6697)

0.0

(0.0, 6697)

n/a

n/a

   Summary

13,206,095

38

11

2.9

(2.0, 3.9)

0.8

(0.4, 1.5)

28.9

(15.4, 45.9)

  1. n/c = not calculated, n/a = not assessable aRisk and confidence intervals not calculated (n/c) for less that 100 vaccinations. Exact confidence intervals based on the binomial distribution. bThe Ratner study age groups, "Age 5 to 14" and "Age 15+", were counted in the Table age groups "Age 5 to 19" and "Age 20+", respectively. cAll ages group may includes subjects whose age was unknown
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BMC Public Health

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