Cell-Mediated Immunity (CMI) for SARS-CoV-2 Infection Among the General Population of North India: A Cross-Sectional Analysis From a Sub-sample of a Large Sero-Epidemiological Study

• Published in: Curēus (Palo Alto, CA) CA), 2023-11, Vol.15 (11), p.e48824-e48824
• Main Authors: Misra, Puneet, Garg, Pramod K, Awasthi, Amit, Kant, Shashi, Rai, Sanjay K, Ahmad, Mohammad, Guleria, Randeep, Deori, Trideep J, Mandal, Suprakash, Jaiswal, Abhishek, Gongal, Gaurav, Vishwakarma, Siddhesh, Bairwa, Mohan, Kumar, Rakesh, Haldar, Partha, Binayke, Akshay
• Format: Article
• Language: English
• Subjects: Antibodies; Antigens; Asymptomatic; COVID-19 vaccines; Data analysis; Infections; Peptides; Population; Public health; Severe acute respiratory syndrome coronavirus 2; Software; Statistical analysis; Viral infections
• ISSN: 2168-8184; 2168-8184
• DOI: 10.7759/cureus.48824

Background Cell-mediated immunity (CMI), or specifically T-cell-mediated immunity, is proven to remain largely preserved against the variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including Omicron. The persistence of cell-mediated immune response in individuals longitudinally followed up for an extended period remains largely unelucidated. To address this, the current study was planned to study whether the effect of cell-mediated immunity persists after an extended period of convalescence or vaccination. Methods Whole blood specimens of 150 selected participants were collected and tested for Anti-SARS-CoV-2 Interferon-gamma (IFN-γ) response. Ex vivo SARS-CoV-2-specific interferon-gamma Enzyme-linked Immunospot (IFN-γ ELISpot) assay was carried out to determine the levels of virus-specific IFN-γ producing cells in individual samples. Findings Out of all the samples tested for anti-SARS-CoV-2 T-cell-mediated IFN-γ response, 78.4% of samples were positive. The median (interquartile range) spots forming units (SFU) per million levels of SARS-CoV-2-specific IFN-γ producing cells of the vaccinated and diagnosed participants was 336 (138-474) while those who were vaccinated but did not have the disease diagnosis was 18 (0-102); the difference between the groups was statistically significant. Since almost all the participants were vaccinated, a similar pattern of significance was observed when the diagnosed and the never-diagnosed participants were compared, irrespective of their vaccination status. Interpretations Cell-mediated immunity against SARS-CoV-2 persisted, irrespective of age and sex of the participant, for more than six months of previous exposure. Participants who had a history of diagnosed COVID-19 infection had better T-cell response compared to those who had never been diagnosed, in spite of being vaccinated.