Humoral profiles of toddlers and young children following SARS-CoV-2 mRNA vaccination
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Nadège Nziza1, Yixiang Deng1,2, Lianna Wood1,3
1Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, USA.
Insights
COVID-19 mRNA vaccines provide strong protection for young children. Vaccinated toddlers showed superior antibody responses compared to adults, even with a lower dose, indicating effectiveness in this age group.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Severe acute and long-term complications from SARS-CoV-2 infection can occur in young children, despite generally mild symptoms.
- Existing mRNA vaccines (mRNA-1273) demonstrate robust protection in individuals aged 5 and older, but their impact on younger children's immune systems is less understood.
Approach:
- A system serology approach was used to analyze antibody responses in children aged 6 months to 5 years vaccinated with mRNA-1273 (25 μg).
- Antibody profiles were compared between vaccinated children, vaccinated adults (100 μg), and naturally infected toddlers/young children.
Key Points:
- Despite a lower vaccine dose, vaccinated toddlers exhibited stronger functional antibody responses, including against SARS-CoV-2 variants of concern (VOCs), compared to vaccinated adults.
- mRNA vaccination in young children resulted in a higher IgG3-dependent humoral immune response against SARS-CoV-2 than natural infection.
- No significant side effects were reported in the vaccinated toddler cohort.
Conclusions:
- mRNA-1273 vaccination is effective in eliciting robust humoral immunity in infants and young children (6 months to 5 years).
- The vaccine induces a superior antibody response in toddlers compared to adults, even at a reduced dosage.
- mRNA vaccination offers a promising strategy for protecting vulnerable young populations against SARS-CoV-2 and its variants.
Abstract:
Although young children generally experience mild symptoms following infection with SARS-CoV-2, severe acute and long-term complications can occur. SARS-CoV-2 mRNA vaccines elicit robust immunoglobulin profiles in children ages 5 years and older, and in adults, corresponding with substantial protection against hospitalizations and severe disease. Whether similar immune responses and humoral protection can be observed in vaccinated infants and young children, who have a developing and vulnerable immune system, remains poorly understood. To study the impact of mRNA vaccination on the humoral immunity of infant, we used a system serology approach to comprehensively profile antibody responses in a cohort of children ages 6 months to 5 years who were vaccinated with the mRNA-1273 COVID-19 vaccine (25 μg). Responses were compared with vaccinated adults (100 μg), in addition to naturally infected toddlers and young children. Despite their lower vaccine dose, vaccinated toddlers elicited a stronger functional antibody response than adults, including against variant of concerns (VOCs), without report of side effects. Moreover, mRNA vaccination was associated with a higher IgG3-dependent humoral profile against SARS-CoV-2 compared to natural infection, supporting that mRNA vaccination is effective at eliciting a robust antibody response in toddlers and young children.
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