The third dose of measles-containing vaccine induces robust immune responses against measles in young seronegative healthcare workers who had previous two-dose measles vaccination

Background: Despite the low measles antibody positivity rate among young healthcare workers (HCWs) who have previously received two doses of a measles-containing vaccine (MCV), whether an additional dose of MCV acts as a booster remains unknown. Thus, we aimed to evaluate the immune responses to a third dose of MCV in young HCWs.Methods: Hospital-wide measles seroprevalence was assessed using enzyme-linked immunosorbent assay (ELISA). The immunogenicity of a third dose of MCV was determined in young seronegative HCWs (born between 1986 and 1997) who had previously received a two-dose measles vaccination.Results: A total of 3033 (92.6%) HCWs had anti-measles immunoglobulin G. The lowest seropositivity rate was observed in HCWs aged 20-24 years (87.7%). In this group, HCWs who received a third dose of MCV had higher seropositivity than those who received a second dose (89.5% vs. 75.4%). A third dose of MCV was administered to 18 HCWs who did not have anti-measles IgG despite two doses. Neutralizing antibody titers increased significantly 4 weeks after the third vaccination. Although neutralizing antibody titers decreased 1 year post vaccination, 17 (94.4%) HCWs had medium (121-900 mIU/mL) or high (> 900 mIU/mL) levels. Furthermore, the third dose of MCV increased the measles virus-specific T-cell effector function.Conclusions: The third dose of MCV induced a strong immune response against measles in young seronegative HCWs who had previously received a two-dose measles vaccination.(c) 2023 Published by Elsevier Ltd on behalf of King Saud Bin Abdulaziz University for Health Sciences.

Automated summary

Young healthcare workers with low measles antibody positivity rates after two doses of measles vaccine showed significantly higher seropositivity and increased neutralizing antibody titers following a third dose of measles vaccine. Additionally, the third dose enhanced measles virus-specific T-cell effector function in this population.