%0 Journal Article
%T Dynamics of anti-SARS-CoV-2 IgG antibody responses following breakthrough infection and the predicted protective efficacy: A longitudinal community-based population study in China.
%A Yan X
%A Zhao X
%A Du Y
%A Wang H
%A Liu L
%A Wang Q
%A Liu J
%A Wei S
%J Int J Infect Dis
%V 145
%N 0
%D 2024 Aug 30
%M 38697605
%F 12.074
%R 10.1016/j.ijid.2024.107075
%X <B>OBJECTIVE: </B>To assess the dynamics of the anti-SARS-CoV-2 IgG antibody levels and their efficacy against COVID-19.<BR><B>METHODS: </B>We conducted a longitudinal serological analysis of 852 breakthrough COVID-19 infections among the community-based population in Yichang, China. Anti-SARS-CoV-2 IgG levels were measured by chemiluminescence at approximately 3, 4, and 9 months after infection. A linear mixed model predicted IgG antibody decline over 18 months. The effectiveness of antibodies in preventing symptomatic and severe infections was determined using an existing meta-regression model.<BR><B>RESULTS: </B>IgG antibodies slowly declined after breakthrough infections. Initially high at around 3 months (339.44 AU/mL, IQR: 262.78-382.95 AU/mL), levels remained significant at 9 months (297.74 AU/mL, IQR: 213.22-360.62 AU/mL). The elderly (≥60 years) had lower antibody levels compared to the young (<20 years) (P < 0.001). The protective efficacy of antibodies against symptomatic and severe infections was lower in the elderly (≥60 years) (78.34% and 86.33%) compared to the young (<20 years) (96.56% and 98.75%) after 1 year.<BR><B>CONCLUSIONS: </B>The study indicated a slow decline in anti-SARS-CoV-2 IgG antibodies, maintaining considerable efficacy for over 1 year. However, lower levels in the elderly suggest reduced protective effects, underscoring the need for age-specific vaccination strategies.