Interactive effect of booster vaccination and vitamin D status on antibody production of Omicron variant‐infected adults: A real‐world cohort study

INTRODUCTION: Effect of booster vaccination and vitamin D status on antibody production of Omicron variant‐infected adults need to be further explored. METHODS: A retrospective, longitudinal, real‐world cohort study was performed. All included cases were divided into vitamin D deficiency (VDD) and non‐VDD (control) groups according to baseline serum 25‐hydroxyvitamin D [25(OH)D] concentration and then into unvaccinated, routinely vaccinated, and booster vaccinated VDD and control subgroups according to vaccination status. Antibody dynamics were observed within six time periods during hospitalization. RESULTS: A total of 204 adult cases were included, of which 121 (59%) were males; 23 (11%), 31 (15%), and 26 (13%) or 50 (25%), 35 (17%), and 39 (19%) were unvaccinated, routinely vaccinated, and booster vaccinated VDD cases or controls, respectively. The median (interquartile range) for age and baseline 25(OH)D concentration was 42.5 (31–53.5) years and 21.5 (18–25.4) ng/mL, respectively. The IgM titers within 3 to 7 days and 7 to 14 days increased rapidly to 1.8‐fold (P < 0.001) and 3.6‐fold (P < 0.001) those within the first day; the IgG titers increased to 5.8‐fold (P < 0.001) and 10.9‐fold (P < 0.001). Booster vaccinated controls had higher first IgG titers compared with unvaccinated controls (3.1‐fold; P = 0.001) or booster vaccinated VDD cases (2.1‐fold; P = 0.02). CONCLUSIONS: Booster vaccination and non‐VDD status may have an interactive boosting effect on IgG production of Omicron variant‐infected adults. Further randomized clinical trials may be needed to determine whether booster vaccination combined with VDD correction improves the humoral immunity to Omicron variants.