Effectiveness of COVID-19 Vaccine Doses in Children: Case of Lake Region Economic Bloc-Kenya

Abstract

Vaccination of children has experienced delays due to paucity of information regarding safety, effectiveness, immunogenicity, and reactogenicity. Age wise approval prioritized 12 - 17 years and later 5 - 11 years. Those below 5 years possess naïve immunity and not considered. In Lake Region Economic Bloc children aged 12 - 17 variably received 1, 2, and 3 doses of vaccine. This analysis looks into effectiveness of the doses administered. Method: Data providers from 84 LREB facilities submitted patients’ vaccination data to Power BI supported dashboard between June 24, 2021 and July 30, 2022. Data of 12 - 17 years old was mined, analyzed and visualized. Sample sizes considered for analysis were 0 dose, n = 8132; 1 dose, n = 271; 2 doses, n = 402, and 3 doses, n = 90. Data used in the analysis was facility operational and not from experimental design. Relative risk analysis of children who received 0, 1, 2, and 3 doses was done using Odds Ratio run on R software. Results: The relative risk of infection to a child with one dose against unvaccinated counterpart is 0.92 (95% CI, 0.61 - 1.43). Likewise the relative risk of infection to a child aged 12 - 17 years with 2 doses against another who received no dose is 0.87 (95% CI, 0.63 - 1.24). A child with 3 doses is 46% over 1st and 2nd doses, respectively, because of incremental reduced risk of infection gained from previous doses. During the period, 15 children at risk were admitted with COVID-19 infections in various regional hospitals, one had 3 doses but confounded with severe comorbidity. Conclusion: We found that 2nd dose had marginal protection over the 1st dose. However, the 3rd dose offers extensive protection compared to 1st and 2nd doses, and protects more against hospitalization. Children at risk should receive 3 doses of vaccines. (95% CI, 27% - 84%) less likely to get infected compared to another not vaccinated. Also, the relative risk between having 2 doses and 1 dose for a child aged 12 - 17 years is 0.95 (95% CI, 0.55 - 1.6). For the same age group the relative risk of having 3 doses of vaccines against 1 dose is 51% (95% CI, 26% - 100%). In addition, a child who receives 3 doses of vaccine is 53% (95% CI, 28% - 100%) less likely to experience breakthrough infection compared to another with 2 doses. Whereas 1st dose offers (5%) marginal protection advantage over the 2nd dose, the 3r dose offers 49% and 47% more protection