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Publications

Journal Article Ppublish

PubMed: 40530661 DOI: 10.1080/21645515.2025.2518654

Immune response to and virological profile of SARS-CoV-2 before and after symptom onset in individuals vaccinated with inactivated COVID-19 vaccines.

Hum Vaccin Immunother 21(1):2518654

Authors: Yandong Cheng, Lei Jiang, Jun Ni, Hongxia Wei, Yaning Zheng, Yingwei Zhang, Zhaoping Zhang, Yi-Hua Zhou, Ping Shen

Affiliations

  • Department of Endocrinology, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.
  • Department of Laboratory Medicine, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.
  • Department of Obstetrics and Gynecology, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.
  • Department of Respiratory Medicine, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.
  • Department of Infectious Diseases and Jiangsu Key Laboratory for Molecular Medicine, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.
  • Department of Laboratory Medicine, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China. Department of Infectious Diseases and Jiangsu Key Laboratory for Molecular Medicine, Nanjing Drum Tower Hospital, Nanjing University Medical School, Nanjing, China.

Abstract

China encountered a COVID-19 pandemic shortly after lifting the zero-COVID-19 policy in December 2022. We prospectively investigated the immune responses to SARS-CoV-2 before and after symptom onset of breakthrough infection in individuals vaccinated with inactivated COVID-19 vaccines. Blood samples from 35 vaccinated participants were collected from December 16 to 20, 2022 when they had no symptoms and a second blood sample was collected from each participant from January 4 to 6, 2023. SARS-CoV-2 RNA, anti-SARS-CoV-2 IgG and IgM, interleukin-6 (IL-6), and C-reactive protein (CRP) were measured with commercially available kits respectively. During a period of average 17.0 (±1.6) days, 30 (85.7%) of 35 participants developed toxemia and respiratory symptoms and 34 (97.1%) were defined with SARS-CoV-2 infection based on positive SARS-CoV-2 RNA in pharyngeal swabs (32) and rising titers of anti-SARS-CoV-2 IgG (34). Before symptom onset, 16 (47.1%), 13 (38.2%), and 5 (14.7%) of the infected individuals already had relatively high anti-SARS-CoV-2 IgG titers, elevated IL-6 and CRP respectively. After 17.0 (±1.6) days, the median anti-SARS-CoV-2 IgG level was significantly increased (46.85 vs 359.45 AU/mL, p < .001), whereas the proportions of elevated IL-6 and CRP were each remarkably reduced. None of the participants infected with SARS-CoV-2 had detectable anti-SARS-CoV-2 IgM. In vaccinated individuals infected with SARS-CoV-2, specific anamnestic immune responses may initiate before symptom onset and robust immune response may develop in very early phase, which should be a critical mechanism to lessen the severity of COVID-19 and reduce the mortality by COVID-19 vaccination.

MeSH

Sars-Cov-2, Vaccines, Covid-19 Vaccines, Interleukin-6, Signs And Symptoms, Covid-19, Immunity, Severe Acute Respiratory Syndrome-Related Coronavirus, Infections