Table 2 Protective efficacies of US FDA-approved COVID-19 vaccines toward five WHO variants of concern

Alpha (B.1.1.7)

89.5% [233]

Reduced levels of neutralizing Abs [234]

70.4% [132]

70.1% (14 days after administration) 70.2% (28 days after administration) [235]

2.9-fold reduction in neutralizing Alpha variant [236]

86% [237]

Beta (B.1.351)

75% [233]

Reduced levels of neutralizing Abs [234]

N.D

38.1% (14 days after administration) 51.9% (28 days after administration) [235]

5.5-fold reduction in neutralizing Beta variant [236]

60% [237]

Gamma (P.1)

N.D

Reduced levels of neutralizing Abs [234]

N.D

36.4% (14 days after administration) 36.5% (28 days after administration)

[235]

51%/4.3-fold reduction in neutralizing Gamma variant [236, 238]

N.D

Delta (B.1.617.2)

88%/90.9%

Dose 2 (2-4W interval) [138, 239]

94.5% Dose 2 (2-4W interval) [138]

67%/82.8% Dose 2 (2-4W interval) [138, 239]

− 6% (14 days after administration) − 5.7% (28 days after administration) [235]

59%/3.4-fold reduction in neutralizing Delta variant [236, 240]

N.D

Omicron (B.1.1.529)

65.5% Dose 2 (2-4W interval) [138]

75.1% Dose 2 (2-4W interval) [138]

48.9% Dose 2 (2-4W interval) [138]

51.8% (14 days after administration) 51.9% (28 days after administration) [235]

12.5-fold reduction in neutralizing Omicron variant [236]

N.D