UPDATE: 8-week interval between the first and second doses of a primary mRNA vaccine schedule
The Centers for Disease Control and Prevention (CDC) updated its COVID-19 vaccination guidance for individuals 12 to 64 years of age, lengthening the interval between the first and second dose of an mRNA vaccine series to 8 weeks, based on the individual patient. These additional considerations followed a thorough evaluation of the latest safety and effectiveness data.
The COVID-19 vaccination primary series schedule for healthy individuals, with updates marked in red:
Primary series vaccine manufacturer | Age group | Number of doses in primary series | Number of booster doses | Interval between 1st and 2nd dose | Interval between primary series and booster dose* |
Pfizer-BioNTech | 5–11 years | 2 | N/A | 3 weeks | N/A |
Pfizer-BioNTech | 12–64 years | 2 | 1 | 8 weeks** | ≥5 months |
Pfizer-BioNTech | >65 years | 2 | 1 | 3 weeks** | ≥5 months |
Moderna | 18–64 years | 2 | 1 | 8 weeks** | ≥5 months |
Moderna | >65 years | 2 | 1 | 4 weeks** | ≥5 months |
Janssen | 18–64 years | 1 | 1 | NA | ≥2 months |
**A shorter interval (3 weeks for Pfizer-BioNTech; 4 weeks for Moderna) between the first and second dose remains the recommended interval for: people who are moderately or severely immunocompromised; adults ages 65 years and older; and others who need early protection due to increased concern about community transmission or risk of severe disease.
Rationale and Summary of Updated Guidance
New data indicate that some people ages 12 through 64 years—and especially males ages 12 through 39 years—would benefit from getting their second mRNA COVID-19 vaccine dose 8 weeks after receiving their first dose. Extending the time interval between primary mRNA COVID-19 vaccine doses from the FDA-approved or authorized 3 weeks (Pfizer-BioNTech) or 4 weeks (Moderna) to 8 weeks may help increase how long protection lasts against COVID-19. It may also help lower the (small) risk of myocarditis (inflammation of the heart muscle) and pericarditis (swelling of tissue around the heart), which has been associated—mostly among adolescent and young adult males—with mRNA COVID-19 vaccination.
It’s important to note this update does not apply to everyone. The 3-week or 4-week interval remains the recommendation for people who are moderately or severely immunocompromised, adults ages 65 years and older, and others who may need early protection due to concern about an increased risk of severe illness from COVID-19 or high levels of community transmission. There are currently no data available for children 5-11 years regarding any impact of intervals longer than 3 weeks between the 1st and 2nd doses of the Pfizer-BioNTech COVID-19 vaccine.
Regardless of the interval between the first and second dose, mRNA vaccines are highly effective at reducing the risk of hospitalization and serious complications from COVID-19 infection. Please note that patients who meet these criteria and have already received their primary mRNA series at the 3-week (Pfizer-BioNTech) or 4-week (Moderna) interval remain well-protected—especially if they have received a booster dose—and do not need to repeat any doses.
To speak to a Public Health Nurse regarding this updated guidance, please contact the East Hartford Health Department at 860-291-7324.