From the Guidelines
Both Pfizer (Comirnaty) and Moderna (mRNA-1273) COVID-19 vaccines are recommended for individuals aged 12 and older, with Pfizer also approved for children as young as 6 months. The primary vaccination series for Pfizer consists of two doses given at least 3-8 weeks apart for those 12 and older, while children 6 months to 11 years receive lower doses with specific intervals depending on age and immunocompromised status 1. Moderna's primary series involves two doses administered at least 4-8 weeks apart for adults, with children receiving age-appropriate reduced doses. Both vaccines require booster doses, typically given at least 2 months after completing the primary series or previous booster.
Key Differences and Recommendations
- For individuals aged 6 months to 4 years, the Pfizer-BioNTech vaccine is recommended with doses 1 and 2 at least 3-8 weeks apart and doses 2 and 3 at least 8 weeks apart for most people, while those who are moderately or severely immunocompromised should receive doses 1 and 2 at least 4 weeks apart and doses 2 and 3 at least 4 weeks apart 1.
- For most people aged 5-11 years, doses 1 and 2 should be at least 3-8 weeks apart and doses 2 and 3 at least 5 months apart, with adjustments for those who are moderately or severely immunocompromised 1.
- The storage requirements differ significantly between Pfizer and Moderna, with Pfizer initially needing ultra-cold storage but able to be refrigerated for up to 31 days after thawing, and Moderna able to be stored at standard freezer temperatures and refrigerated for up to 30 days.
- Both mRNA vaccines have similar efficacy profiles and side effect patterns, including injection site pain, fatigue, headache, and muscle pain 1.
Booster Dose Recommendations
- For most people aged 12-17 years who received the Moderna vaccine, the Pfizer-BioNTech bivalent booster may be given at least 8 weeks from doses 2 and 3, with adjustments for those moderately or severely compromised 1.
- For those 18 years of age receiving the Moderna vaccine, the Moderna bivalent booster may be given 8 weeks after their last dose 1.
- The choice between Pfizer and Moderna for booster doses depends on factors such as age, immunocompromised status, and previous vaccine doses, with recommendations provided for various scenarios 1.
From the Research
Overview of Pfizer and Moderna Covid-19 Vaccines
- The Pfizer (Comirnaty) and Moderna (mRNA-1273) Covid-19 vaccines are both mRNA-based vaccines that have been authorized for emergency use by the US Food and Drug Administration 2.
- The vaccines have been shown to be highly effective in preventing Covid-19, with efficacy rates of 95% and 94.1% reported for the Pfizer and Moderna vaccines, respectively, after the second dose 2.
Recommended Use
- The Advisory Committee on Immunization Practices (ACIP) has recommended the use of the Moderna Covid-19 vaccine in persons aged ≥18 years, with a standard recommendation for use of the fully licensed vaccine 3.
- The ACIP has also considered the use of an 8-week interval between doses, which may be optimal for some adolescents and adults 3.
- The Pfizer-BioNTech vaccine is authorized and recommended for persons aged ≥12 years, while the Moderna and Janssen vaccines are authorized and recommended for persons aged ≥18 years 4.
Comparative Effectiveness
- A study comparing the effectiveness of the Moderna, Pfizer-BioNTech, and Janssen vaccines in preventing Covid-19 hospitalizations found that the Moderna vaccine had a higher effectiveness (93%) compared to the Pfizer-BioNTech vaccine (88%) and the Janssen vaccine (71%) 5.
- Another study found that the relative mortality risk for Pfizer vaccinees was consistently higher than for Moderna vaccinees, especially for older adults, and that the Pfizer-Moderna gap was much smaller and statistically insignificant for booster recipients 6.
Safety and Adverse Events
- The vaccines have been found to be safe, with mostly mild to moderate adverse events, such as injection-site reactions and fatigue, and no serious adverse events reported 2.
- The ACIP has reviewed data on serious adverse events, including thrombosis with thrombocytopenia syndrome, Guillain-Barré syndrome, and myocarditis, and has determined that the benefits of Covid-19 vaccination outweigh the risks for these rare serious adverse events in adults aged ≥18 years 4.