Comparison of the Clinical Features, Viral Shedding and Immune Response in Vaccine Breakthrough Infection by the Omicron and Delta Variants

• DOI: 10.2139/ssrn.4142078
• Publication Date: 2022-06-28T12:19:53Z
• Authors: Sai Meng Tham; Siew‐Wai Fong; Zi-Wei Chang; Kai Sen Tan; Angeline Rouers; Yun Shan Goh; Douglas Jie Wen Tay; Sean Wei Xiang Ong; Ying Hao; Siang Li Chua; Jean-Marc Chavatte; Lin Cui; Matthew Zirui Tay; Raymond Tzer Pin Lin; Laurent Renia; Yee-Sin Leo; Justin Jang Hann Chu; David Chien Lye; Lisa F.P. Ng; Barnaby E. Young; PROTECT Cohort St...
• Keywords: Viral Shedding

Background: On 26 November 2021, the World Health Organization designated B.1.1.529 lineage of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as fifth variant concern, Omicron. Infections have quickly spread worldwide but understanding viral dynamics and cytokine cellular immunological response during infection remain limited. Methods: Detailed patient-level data from 174 age-matched patients with sequence confirmed Omicron or Delta (87 each group) admitted to National Centre for Infectious Diseases, Singapore were analysed in an observational cohort study. All had received a primary vaccination series against SARS-CoV-2. Peripheral blood samples measurement SARS-CoV-2 parameters obtained subset. collected cultures correlated corresponding PCR cycle threshold (Ct) values. Results: infections this hospitalized mild only 3 (3/87; 3%) 14 (14/87; 16%) developing pneumonia respectively. more likely present sore throat (46·0 vs 23·0%, p=0·005). Neutrophil counts C-reactive protein (CRP) significantly lower among (Median neutrophil 2·95 [IQR 2·16 – 3·96] 4·60 3·76 6·10] x 109/L, p<0·001; Median CRP 5·7 2·0 10·0] 12·0 6·1 22·0] mg/L, p<0·001). Mean peak loads (Ct 17·6 16·3 19·3]) compared 14·9 13·9 19·0]) (p=0·001). The pattern rate change load based on Ct values was similar between Delta. At time infection, vaccine breakthrough low concentration proinflammatory cytokines, chemokines, growth factors at acute phase robust IFN-γ response. Less dysregulated immune cell profiles also observed, including immature count cases Conclusions: resulted illness majority patients. Compared Delta, frequently associated upper respiratory tract infections, loads, levels pro-inflammatory cytokines less profiles.Funding: This work supported by Biomedical Research Council (BMRC), A*CRUSE (Vaccine monitoring project), A*ccelerate GAP-funded project (ACCL/19-GAP064-R20H-H) Agency Science, Technology (A*STAR), Medical COVID-19 Fund (COVID19RF-001; COVID19RF-007; COVID19RF-0008; COVID19RF-060; OF-LCG19May-0034), Grant Program Diabetes, Tuberculosis Neuroscience CGAug16M009 A*STAR funding (H/20/04/g1/006).Declaration Interest: None declare. Ethical Approval: Waiver informed consent collection clinical individuals infected granted Ministry (MOH), Singapore, under Diseases Act part outbreak investigation. Retrospective approved institutional ethics committee (REF: 2020/01122). Written study participants biological after review (REF DSRB: 2012/00917).