Which COVID-19 (Coronavirus Disease 2019) vaccine is used for a booster dose?

COVID-19 Vaccine Boosters: Current Recommendations

For COVID-19 booster vaccination, bivalent mRNA vaccines (Pfizer-BioNTech or Moderna) are the recommended options for all eligible individuals aged 5 years and older. 1

Recommended Booster Vaccines by Age Group

The Advisory Committee on Immunization Practices (ACIP) and CDC recommend specific COVID-19 booster vaccines based on age:

• Ages 5 years: Pfizer-BioNTech bivalent vaccine only 1
• Ages 6-11 years: Either Moderna or Pfizer-BioNTech bivalent vaccine 1
• Ages 12-17 years: Either Moderna or Pfizer-BioNTech bivalent vaccine 1
• Ages 18 years and older: Either Moderna or Pfizer-BioNTech bivalent vaccine (primary option) 1

Special Considerations

Novavax Option for Adults

• A monovalent Novavax booster may be used in limited situations for adults ≥18 years who:
  • Have completed any FDA-approved/authorized primary series
  • Have not received any previous booster doses
  • Cannot receive an mRNA vaccine due to contraindication or unavailability, OR
  • Are unwilling to receive an mRNA vaccine and would otherwise not receive a booster 1

Timing of Booster Doses

• Bivalent mRNA boosters should be administered ≥2 months after completion of primary series or previous monovalent booster 1
• Novavax monovalent booster should be administered ≥6 months after completion of primary series 1
• Persons who recently had SARS-CoV-2 infection may consider delaying their booster dose by 3 months from symptom onset or positive test result 1, 2

Rationale for Bivalent Boosters

The shift to bivalent boosters occurred because:

1. Protection from monovalent boosters decreased after the emergence of Omicron subvariants 1
2. Bivalent vaccines contain components from both the ancestral strain and Omicron BA.4/BA.5 variants 1
3. Bivalent boosters improve protection against emerging SARS-CoV-2 Omicron sublineages 1, 2

Effectiveness of Boosters

Research demonstrates significant benefits of bivalent boosters:

• In adults aged ≥65 years, bivalent mRNA boosters reduced COVID-19 hospitalization risk by 72% compared to those without boosters (adjusted hazard ratio 0.28) 3
• The absolute risk reduction for hospitalization was 0.089%, with a number needed to vaccinate of 1118 people to prevent one hospitalization 3
• Among nursing home residents, additional primary or booster doses provided 46.9% greater protection against Omicron infection compared to primary series alone 4

Important Clinical Considerations

• Immunocompromised individuals: Should follow specific vaccination schedules as they may require additional doses 2
• Children under 5 years: No booster doses are currently authorized for this age group 1
• Implementation strategy: Boosters should be administered in conjunction with other COVID-19 prevention strategies, particularly in high-risk settings like nursing homes 4

Common Pitfalls to Avoid

1. Using outdated monovalent boosters: As of August 31,2022, monovalent mRNA vaccines based on the ancestral strain are no longer authorized for use in the United States 5
2. Administering boosters too soon: Administering boosters less than 2 months after previous vaccination may reduce effectiveness
3. Overlooking recent COVID-19 infection: Consider delaying booster by 3 months after infection to optimize immune response 1, 2
4. Failing to identify eligible high-risk populations: Ensure all eligible nursing home residents and immunocompromised individuals receive appropriate additional or booster doses 4

The evidence strongly supports using bivalent mRNA vaccines as the standard for COVID-19 boosters, with specific age-appropriate formulations and timing considerations to maximize protection against severe disease.