The effectiveness and safety of the Moderna mRNA-based COVID-19 vaccine in children older than 6 months
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Reviewed by Dat Tien Nguyen, B.A, ScM.
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Posted on November 4th, 2022
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In mid-June of 2022, the US Food and Drugs Administration recommended the usage of COVID-19 vaccines for children above the age of 6 months. Later in July of the same year, the Ministry of Health in Vietnam made the same recommendation. A recent multicenter study conducted in the United States and Canada had investigated the efficacy and safety of the mRNA-1273 vaccines manufactured by Moderna.
The trial includes a total of 6403 children, and has 2 phases with distinct objectives; the first portion was conducted to determine the most ideal dose between 25 μg and 50 μg. After the dose-finding phase, 25 μg was chosen as the standard dose to compare safety, immunogenicity and efficacy during the last part of the study. The vaccine was administered following a 2-dose regimen that is 28 days apart. When compared to placebo groups, local and systemic adverse events are more common in those who have received the mRNA-1273 vaccine. In terms of immunogenicity, the rate of seroconversion is comparable to adult subjects enrolled in another previous reference study. And the regimen resulted in antibodies that are effective at neutralizing the B.1.351 (Beta), B.1.617.2 (Delta), and Omicron variants. This clinically translated to a vaccine effectiveness rate of 50.6% for children between the age of 6 and 23 months old and 36.8% for children between the age of 2 to 5 years old. This low efficacy is alarming but consistent with findings in trials conducted in adults and adolescents reporting a reduced efficacy against the Omicron variant
The trial includes a total of 6403 children, and has 2 phases with distinct objectives; the first portion was conducted to determine the most ideal dose between 25 μg and 50 μg. After the dose-finding phase, 25 μg was chosen as the standard dose to compare safety, immunogenicity and efficacy during the last part of the study. The vaccine was administered following a 2-dose regimen that is 28 days apart. When compared to placebo groups, local and systemic adverse events are more common in those who have received the mRNA-1273 vaccine. In terms of immunogenicity, the rate of seroconversion is comparable to adult subjects enrolled in another previous reference study. And the regimen resulted in antibodies that are effective at neutralizing the B.1.351 (Beta), B.1.617.2 (Delta), and Omicron variants. This clinically translated to a vaccine effectiveness rate of 50.6% for children between the age of 6 and 23 months old and 36.8% for children between the age of 2 to 5 years old. This low efficacy is alarming but consistent with findings in trials conducted in adults and adolescents reporting a reduced efficacy against the Omicron variant