Table 3

Efficacy and effectiveness of COVID-19 vaccine primary series against symptomatic infection and severe outcomes by variant in children

Vaccine typeVaccine efficacy and effectiveness
<12 years (except where specified 3–17 years)12–17 years
Moderna
(mRNA)
Omicron efficacy against
  • Symptomatic infection: 55% (6 months to <2 years) and 38% (2–6 years)48


Omicron effectiveness against
  • Any infection: 18% (3–17 years)52

Pre-Omicron efficacy against
  • Symptomatic infection: 93% (12–17 years)114

Pfizer-BioNTech
(mRNA)
Pre-Omicron: efficacy against
  • Symptomatic infection: 91% (5 to <12 years)115


Delta and Omicron effectiveness against
  • Any infection 0–13 days post-vaccination: 65% (5–11 years)116

  • Any infection 28–34 days post-vaccination: 12% (5–11 years)116

  • Hospitalisation 14–67 days post-vaccination: 74% (5–11 years)117

  • MIS-C: 94% in Denmark (5–17 years)25


Omicron effectiveness against
  • Any infection 0–14 days post-vaccination: 39% (5–11 years)118

  • Any infection 43–84 days post-vaccination: 21% (5–11 years)118

  • Any infection: 28% (3–17 years)52

  • Symptomatic infection 2 months post-vaccination: 29% (5–11 years)119

  • Symptomatic infection: 80.4% (6 months–4 years)47

Alpha and Delta efficacy against
  • Symptomatic infection: 100% (12–15 years)120


Delta effectiveness against
  • Symptomatic infection 7–21 days post-vaccination: 93% (12–18 years)121

  • Symptomatic infection 14–27 days post-vaccination: 86% in Brazil and 91% in Scotland (12–17 years)122

  • Hospitalisation: 94% (12–18 years)123

  • MIS-C: 91% in France and USA (12–18 years)24 26


Delta and Omicron effectiveness against
  • Any infection 0–13 days post-vaccination: 76% (12–17 years)116; 80% (16–17 years) and 79% (12–15 years)124

  • Any infection 14–29 days post-vaccination: 83% (16–17 years) and 77% (12–15 years)124

  • Any infection 28–34 days post-vaccination: 56% (12–17 years)116

  • Any infection 30–59 days post-vaccination: 61% (16–17 years) and 50% (12–15 years)124

  • Hospitalisation 14–149 days post-vaccination: 92% (12–15 years) and 94% (16–17 years)117


Omicron effectiveness against
  • Symptomatic infection 14–27 days post-vaccination: 63% in Brazil and 78% in Scotland (12–17 years)122

  • Symptomatic infection 7–34 days post-vaccination: 53% (16–17 years)125

  • Symptomatic infection ≥63 days post-vaccination: 23% (16–17 years)125

  • Symptomatic infection 2 months post-vaccination: 17% (12–15 years)119

  • Symptomatic infection ≥98 days post-vaccination: 14% in Brazil and 31% in Scotland (12–17 years)122

  • Hospitalisation: 81% (12–17 years)126

  • Hospitalisation or death ≥98 days post-vaccination: 85% (12–17 years)122

Novavax (protein subunit)Delta efficacy against
  • Symptomatic infection: 80% (12–17 years)127

Sinovac
(inactivated virus)
Delta and Omicron effectiveness against
  • Symptomatic infection: 76% (6–11 years)128

  • Hospitalisation: 78% (6–11 years)128


Omicron effectiveness against
  • Symptomatic infection: 40% (6–11 years)50

  • Hospitalisation: 59% (6–11 years)50

  • Any infection: 38% (3–5 years)51

  • Hospitalisation: 65% (3–5 years)51

Sinopharm
(inactivated virus)
Omicron effectiveness against
  • Any infection: 28% (3–17 years)52

AstraZeneca
(viral vector)
Trials suspended when evidence emerged of the higher risk of thrombosis with thrombocytopaenia syndrome in adults
  • MIS-C, multisystem inflammatory syndrome in children.