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Table 5 Risk of generalized vaccinia (G.V.) and accidental infection (A.I.) 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

   Generalized vaccinia Accidental infection
Age group and studies Number vaccinated G.V. No. Deaths No. Risk of complication per million (95% C.I.)a Number vaccinated A.I. No. Deaths No. Risk of complication per million (95% C.I.)a
Age <1           
   Neff 1967a 654,000 52 0 79.5 (59.4, 104) 654,000 7 0 10.7 (4.3, 22.0)
   Neff 1967b 31,000 12 0 387.1 (200, 676) n/a n/a n/a n/a n/a
   Lane 1969 614,000 43 0 70.0 (50.7, 94.3) 614,000 7 0 11.4 (4.6, 23.5)
   Lane 1970 17,000 28 0 1647 (1095, 2380) 17,000 36 0 2117.6 (1484, 2930)
   Ratner 1970 1 1 0 n/c n/c 1 0 0 n/c n/c
   Neff 1972 32 0 0 n/c n/c 32 0 0 n/c n/c
   Summary 1,316,033 136 0 103.3 (86.7, 122.2) 1,285,033 50 0 38.9 (28.9, 51.3)
Age 1 to 4           
   Neff 1967a 2,973,000 46 0 15.5 (11.3, 20.6) 2,973,000 40 0 13.4 (9.6, 18.3)
   Neff 1967b 142,000 24 0 169.0 (108, 251) n/a n/a n/a n/a n/a
   Lane 1969 2,733,000 47 0 17.2 (12.6, 22.9) 2,733,000 91 0 33.3 (26.8, 40.9)
   Lane 1970 317,000 74 0 233.4 (183, 293) 317,000 183 0 577.3 (497, 667)
   Ratner 1970 68,002 6 0 88.2 (32.4, 192) 68,002 3 0 44.1 (9.1, 129)
   Neff 1972 517 0 0 0.0 (0.0, 7110) 517 3 0 5802.7 (1198, 16,864)
   Summary 6,233,519 197 0 31.6 (27.3, 36.3) 6,091,519 320 0 52.5 (46.9, 58.6)
Age 5 to 19           
   Neff 1967a 2,295,000 24 0 10.5 (6.7, 15.6) 2,295,000 33 0 14.4 (9.9, 20.2)
   Neff 1967b 110,000 17 0 154.5 (90.0, 247) n/a n/a n/a n/a n/a
   Lane 1969 1,959,000 25 0 12.8 (8.3, 18.8) 1,959,000 35 0 17.9 (12.4, 24.8)
   Lane 1970 229,000 32 0 139.7 (95.6, 197) 229,000 85 0 371.2 (296, 459)
   Ratner 1970b 193,721 9 0 46.5 (21.2, 88.2) 193,721 2 0 10.3 (1.2, 37.3)
   Summary 4,786,721 107 0 22.4 (18.3, 27.0) 4,676,721 155 0 33.1 (28.1, 38.8)
Age 20 +           
   Neff 1967a 317,000 6 0 18.9 (6.9, 41.2) 317,000 4 0 12.6 (3.4, 32.3)
   Neff 1967b 15,000 2 0 133.3 (16.1, 482) n/a n/a n/a n/a n/a
   Lane 1969 288,000 13 0 45.1 (24.0, 77.2) 288,000 4 0 13.9 (3.8, 35.6)
   Lane 1970 33,000 7 0 212.1 (85.3, 437) 33,000 20 0 606.1 (370, 936)
   Ratner 1970b 107,822 10 0 92.7 (44.5, 171) 107,822 8 0 74.2 (32.0, 146)
   Summary 760,822 38 0 49.9 (35.3, 68.6) 745,822 36 0 48.3 (33.8, 66.8)
All agesc           
   Neff 1967a 6,239,000 130 0 20.8 (17.4, 24.7) 6,239,000 85 0 13.6 (10.9, 16.8)
   Neff 1967b 298,000 71 0 238.3 (186.1, 300) 298,000 250 0 838.9 (738, 950)
   Lane 1969 5,594,000 131 0 23.4 (19.6, 27.8) 5,594,000 142 0 25.4 (21.4, 23.0)
   Lane 1970 596,000 157 0 263.4 (224, 308) 596,000 344 0 577.2 (518, 641)
   Mellin 1970 109,000 12 0 110.1 (56.9, 192) 109,000 20 0 183.5 (112, 283)
   Ratner 1970 369,546 26 0 70.4 (46.0, 103) 369,546 13 0 35.2 (18.7, 60.1)
   Neff 1972 549 0 0 0.0 (0.0, 6697) 549 3 0 5464.5 (1128, 15,885)
   Summary 13,206,095 527 0 39.9 (36.6, 43.5) 13,206,095 857 0 64.9 (60.6, 69.4)
  1. n/c = not calculated, n/a = not available from this study 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 includes subjects whose age was unknown