Is it beneficial to receive COVID-19 (Coronavirus Disease 2019) booster shots after the primary series of COVID-19 vaccination?

COVID-19 Booster Vaccination Benefits After Primary Series

COVID-19 booster vaccinations provide significant additional protection against severe disease, hospitalization, and death compared to the primary series alone, and are recommended for all eligible individuals aged ≥5 years. 1, 2

Evidence for Booster Effectiveness

The evidence strongly supports the benefit of COVID-19 booster doses:

• During the Omicron variant predominance, vaccine effectiveness (VE) against COVID-19-associated hospitalizations was:

  • 57% at ≥180 days after primary series completion
  • 90% at ≥14 days after receiving a booster dose 3

• For COVID-19-associated emergency department and urgent care visits:

  • 38% VE at ≥180 days after primary series completion
  • 82% VE at ≥14 days after receiving a booster dose 3

• Protection from the primary series wanes over time, particularly against newer variants like Omicron, making boosters essential for maintaining immunity 4

Current Recommendations by Age Group

The CDC and Advisory Committee on Immunization Practices (ACIP) recommend:

For Ages 5+ Years:

• Bivalent mRNA COVID-19 vaccine booster dose administered ≥2 months after completing the primary series or after receipt of a monovalent booster dose 1

For Adults ≥18 Years:

• Moderna or Pfizer-BioNTech bivalent booster is preferred
• Novavax monovalent booster may be used in limited situations for those who:
  • Cannot receive mRNA vaccines due to contraindications
  • Are unwilling to receive mRNA vaccines and would otherwise not receive a booster 1

Special Considerations

Timing After COVID-19 Infection

• Persons who recently had SARS-CoV-2 infection should consider delaying their booster dose by 3 months from symptom onset or positive test result 2
• This timing allows for optimal immune response development following natural infection 2

Immunocompromised Individuals

• May require additional doses for optimal protection
• Should receive at least 1 dose of the 2024-2025 COVID-19 vaccine
• May receive an additional age-appropriate dose at least 2 months after the last recommended dose 2

Common Pitfalls to Avoid

1. Waiting too long after infection: While a 3-month interval after infection is recommended, waiting significantly longer may leave individuals vulnerable as natural immunity wanes 2

2. Assuming primary series provides sufficient long-term protection: VE against hospitalization drops from 81% at 14-179 days to 57% at ≥180 days after primary series completion during Omicron predominance 3

3. Overlooking the need for boosters in younger populations: While older adults benefit most, boosters are recommended for all eligible age groups ≥5 years 1

Algorithm for Booster Decision-Making

1. Has the individual completed a primary COVID-19 vaccine series?

   • If no: Complete primary series first
   • If yes: Continue to next step

2. Has it been ≥2 months since primary series completion or last booster?

   • If no: Wait until reaching 2-month interval
   • If yes: Proceed with booster unless recent COVID-19 infection

3. Has the individual had recent COVID-19 infection?

   • If yes: Consider delaying booster by 3 months from symptom onset/positive test
   • If no: Proceed with booster immediately

4. Is the individual immunocompromised?

   • If yes: Follow specialized dosing schedule with potential for additional doses
   • If no: Follow standard booster schedule

The evidence clearly demonstrates that while primary vaccination provides important protection, booster doses significantly enhance and restore waning immunity, particularly against severe outcomes from COVID-19 infection.