tetano
Editor, Senior Moderator
BMC Infect Dis
. 2025 Nov 17;25(1):1600.
doi: 10.1186/s12879-025-11845-y. The impact of Omicron infection on antibody response and attenuation: a six-month follow-up study
Yanfei Wu[SUP] 1 [/SUP], Shaohua Guo[SUP] 1 [/SUP], Suyi Zhang[SUP] 2 3 [/SUP], Weibing Wang[SUP] 3 4 [/SUP], Pengfei Deng[SUP] 1 [/SUP], Bing Zhao[SUP] 1 [/SUP], Xiao Wang[SUP] 1 [/SUP], Shaotan Xiao[SUP] 1 [/SUP], Laibao Yang[SUP] 5 [/SUP]
Affiliations
Background: Antibody patterns to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are the subject of the current study, and the variations in antibodies to Omicron are yet unknown. The study investigated the 6-month longitudinal dynamics and influencing factors of antibodies, including immunoglobulin (Ig) G, IgM, and neutralizing antibodies (NAbs), in healthcare workers (HCWs) following Omicron infection.
Methods: The prospective cross-sectional study in Shanghai recruited HCWs testing positive for Omicron through multistage sampling, and were followed up six times with blood sampling and questionnaires. The titers of the specific NAb against Omicron and the cut-off index (COI) of IgG/IgM against Omicron were tested by chemiluminescent immunoassay. Antibody decay models were developed based on individual data from participants with the single Omicron infection, and statistical analyses were conducted using Mann-Whitney U and Kruskal-Wallis tests.
Results: A total of 710 HCWs were enrolled. After the single infection, IgG exhibited a mean short-term increase of 70.07 COI and a long-term elevation of 33.63 COI, with a gradual decline at a rate of - 0.0024 COI per day. IgM demonstrated a transient elevation, with a short-term boost of 23.66 COI and a modest long-term increase of 0.63, followed by a more rapid decay at - 0.0664 COI per day. NAb similarly rose significantly post-infection, with a short-term increase of 295.28 antibody units (AU)/ml and a sustained long-term elevation of 292.07 AU/ml, declining at a rate of - 0.0021 AU/ml per day. IgG and NAb remained high for 5 months but declined significantly in the sixth, while IgM declined rapidly throughout. Reinfection occurred in 36.76% of HCWs, boosting antibody levels. Timing between infection and vaccination significantly influenced the waning of IgG/IgM but not NAbs. No associations were found between antibody decay and demographic or clinical factors.
Conclusion: While Omicron infection induces robust short-term antibody responses, immunity wanes significantly within 6 months, and reinfection temporarily boosts antibody levels. The findings highlight the limited durability of natural and hybrid immunity and underscore the need for timely booster vaccinations to sustain protection, particularly in high-risk groups like HCWs.
Keywords: Antibody waning; Healthcare workers; IgG; IgM; Neutralizing antibodies; Omicron; Reinfection; Vaccination timing.
. 2025 Nov 17;25(1):1600.
doi: 10.1186/s12879-025-11845-y. The impact of Omicron infection on antibody response and attenuation: a six-month follow-up study
Yanfei Wu[SUP] 1 [/SUP], Shaohua Guo[SUP] 1 [/SUP], Suyi Zhang[SUP] 2 3 [/SUP], Weibing Wang[SUP] 3 4 [/SUP], Pengfei Deng[SUP] 1 [/SUP], Bing Zhao[SUP] 1 [/SUP], Xiao Wang[SUP] 1 [/SUP], Shaotan Xiao[SUP] 1 [/SUP], Laibao Yang[SUP] 5 [/SUP]
Affiliations
- PMID: 41249972
- PMCID: PMC12625540
- DOI: 10.1186/s12879-025-11845-y
Background: Antibody patterns to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are the subject of the current study, and the variations in antibodies to Omicron are yet unknown. The study investigated the 6-month longitudinal dynamics and influencing factors of antibodies, including immunoglobulin (Ig) G, IgM, and neutralizing antibodies (NAbs), in healthcare workers (HCWs) following Omicron infection.
Methods: The prospective cross-sectional study in Shanghai recruited HCWs testing positive for Omicron through multistage sampling, and were followed up six times with blood sampling and questionnaires. The titers of the specific NAb against Omicron and the cut-off index (COI) of IgG/IgM against Omicron were tested by chemiluminescent immunoassay. Antibody decay models were developed based on individual data from participants with the single Omicron infection, and statistical analyses were conducted using Mann-Whitney U and Kruskal-Wallis tests.
Results: A total of 710 HCWs were enrolled. After the single infection, IgG exhibited a mean short-term increase of 70.07 COI and a long-term elevation of 33.63 COI, with a gradual decline at a rate of - 0.0024 COI per day. IgM demonstrated a transient elevation, with a short-term boost of 23.66 COI and a modest long-term increase of 0.63, followed by a more rapid decay at - 0.0664 COI per day. NAb similarly rose significantly post-infection, with a short-term increase of 295.28 antibody units (AU)/ml and a sustained long-term elevation of 292.07 AU/ml, declining at a rate of - 0.0021 AU/ml per day. IgG and NAb remained high for 5 months but declined significantly in the sixth, while IgM declined rapidly throughout. Reinfection occurred in 36.76% of HCWs, boosting antibody levels. Timing between infection and vaccination significantly influenced the waning of IgG/IgM but not NAbs. No associations were found between antibody decay and demographic or clinical factors.
Conclusion: While Omicron infection induces robust short-term antibody responses, immunity wanes significantly within 6 months, and reinfection temporarily boosts antibody levels. The findings highlight the limited durability of natural and hybrid immunity and underscore the need for timely booster vaccinations to sustain protection, particularly in high-risk groups like HCWs.
Keywords: Antibody waning; Healthcare workers; IgG; IgM; Neutralizing antibodies; Omicron; Reinfection; Vaccination timing.