Table 1 Vaccine effectiveness against Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Beta/Gamma and Delta (B.1.617.2) variants of concern by outcome, vaccine product, number of doses received, and time between most recent vaccination date and index date for those tested for SARS-CoV-2 between 14 December 2020 and 3 August 2021 in Ontario, Canada

From: Effectiveness of COVID-19 vaccines against symptomatic SARS-CoV-2 infection and severe outcomes with variants of concern in Ontario

Outcome

Vaccine effectivenessa (95% CI)

 

Alpha

Beta

Gamma

Beta/Gammab

Deltac

Non-VOC SARS-CoV-2

Symptomatic infection

BNT162b2 (Pfizer-BioNTech Comirnaty)d

 ≥14 d after one dose only

67 (65, 68)

50 (15, 70)

63 (54, 70)

64 (54, 72)

57 (53, 61)

63 (56, 68)

 ≥21 d after one dose only

70 (69, 72)

48 (6, 71)

67 (57, 74)

68 (57, 76)

59 (54, 63)

65 (58, 71)

 ≥7 d after two doses

89 (87, 90)

87 (8, 98)

88 (73, 94)

82 (65, 91)

92 (90, 94)

93 (88, 95)

 ≥14 d after two doses

88 (86, 90)

86 (0, 98)

90 (76, 96)

89 (74, 96)

92 (89, 94)

92 (87, 95)

mRNA-1273 (Moderna Spikevax)d

 ≥14 d after one dose only

82 (80, 84)

−e

89 (76, 95)

75 (53, 86)

70 (64, 76)

63 (47, 74)

 ≥21 d after one dose only

83 (80, 85)

−e

90 (73, 96)

74 (48, 87)

69 (62, 75)

70 (51, 81)

 ≥7 d after two doses

92 (88, 95)

−f

−f

89 (21, 98)

95 (91, 97)

96 (85, 99)

 ≥14 d after two doses

92 (87, 95)

−f

−f

88 (10, 98)

94 (90, 97)

98 (83, 100)

ChAdOx1 (AstraZeneca Vaxzevria)d

 ≥14 d after one dose only

63 (59, 66)

84 (−13, 98)

41 (12, 60)

62 (37, 77)

68 (57, 76)

67 (44, 81)

 ≥21 d after one dose only

71 (67, 74)

79 (−53, 97)

46 (13, 66)

59 (29, 76)

68 (57, 76)

80 (56, 91)

 ≥7 d after two doses

91 (62, 98)

−f

−f

−e

87 (69, 95)

−f

 ≥14 d after two doses

87 (47, 97)

−f

−f

−e

88 (68, 96)

−f

Hospitalization or death

BNT162b2 (Pfizer-BioNTech Comirnaty)d

 ≥14 d after one dose only

82 (81, 84)

64 (31, 82)

80 (70, 87)

84 (74, 90)

81 (76, 85)

77 (67, 84)

 ≥21 d after one dose only

87 (85, 88)

65 (23, 84)

88 (79, 93)

87 (77, 92)

81 (76, 85)

88 (79, 94)

 ≥7 d after two doses

96 (94, 97)

93 (46, 99)

89 (57, 97)

96 (68, 99)

97 (96, 98)

98 (90, 99)

 ≥14 d after two doses

96 (94, 97)

92 (39, 99)

94 (59, 99)

95 (64, 99)

98 (96, 99)

97 (88, 99)

mRNA-1273 (Moderna Spikevax)d

 ≥14 d after one dose only

80 (76, 84)

59 (−77, 90)

88 (63, 96)

96 (68, 99)

90 (82, 94)

66 (43, 80)

 ≥21 d after one dose only

82 (77, 86)

−e

95 (63, 99)

−f

91 (83, 95)

70 (41, 85)

 ≥7 d after two doses

95 (92, 97)

−f

−f

−f

98 (93, 99)

97 (78, 100)

 ≥14 d after two doses

95 (92, 97)

−f

−f

−f

98 (93, 100)

−f

ChAdOx1 (AstraZeneca Vaxzevria)d

 ≥14 d after one dose only

87 (83, 90)

61 (−64, 91)

89 (65, 97)

76 (40, 90)

91 (82, 96)

92 (45, 99)

 ≥21 d after one dose only

91 (88, 94)

73 (−98, 96)

86 (57, 96)

72 (28, 89)

91 (81, 95)

90 (27, 99)

 ≥7 d after two doses

82 (43, 94)

−e

−f

−f

91 (72, 97)

−f

 ≥14 d after two doses

92 (41, 99)

−e

−f

−f

90 (67, 97)

−f

  1. aAdjusted for age, sex, public health unit region, period of test (weekly period for Delta, and biweekly period for non-VOC SARS-CoV-2 and other VOC), number of SARS-CoV-2 tests in the 3 months before 14 December 2020, presence of any comorbidity that increase the risk of severe COVID-19, receipt of 2019/2020 and/or 2020/2021 influenza vaccination, and Census dissemination area-level quintiles of household income, proportion of persons employed as non-health essential workers, persons per dwelling, and proportion of self-identified visible minorities.
  2. bRT–PCR testing dates for both test-positive cases and test-negative controls were restricted to 11 January 2021 to 3 August 2021 for Beta, Gamma, and Beta/Gamma.
  3. cRT–PCR testing dates for both test-positive cases and test-negative controls were restricted to 5 April 2021 to 3 August 2021 for Delta.
  4. dFor one dose only, excludes individuals who received two doses; shorter intervals after the doses include the longer interval (that is, analyses for ≥14 d after the first dose also includes subjects who were ≥21 d after the first dose, and analyses for ≥7 d also includes subjects who were ≥14 d after the second dose).
  5. eVaccine effectiveness not reported due to extremely imprecise 95% confidence intervals.
  6. fVaccine effectiveness estimated as 100% on the basis of zero vaccinated test-positive cases.
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