Sinopharm and Sinovac COVID-19 vaccines; Prevalence and risk factors for post full vaccination weak immunity.


  • Sahibzada Syed Masood us Syed SMC, Sialkot.
  • Abid Ali Ranjha Sialkot Medical College (SMC), Sialkot.
  • Sidra Ghazanfer Khawaja Muhammad Sader Medical College, Sialkot.
  • Syed Muhammad Shah Hussain Miran Usman General Hospital, Sialkot.
  • Syeda Zahra Najam SMC, Sialkot.
  • Syeda Kainat Fatima SMC.
  • Hassan Osman Muhmood Colonel Sultan's Lab, Sialkot.
  • Hamda Saqib Imran Idrees Teaching Hospital, Sialkot.



Body Mass Index, COVID-19 Vaccines, Immunoglobulin G, Prevalence, Risk Factors


Objective: To see the prevalence and risk factors for post full vaccination (Sinopharm and Sinovac COVID-19 vaccines) weak immunity in persons with no history of viral exposure. Study Design: Prospective Observational. Setting: Syed Research Centre, Sialkot. Period: Nov 2021 to Feb 2022. Material & Methods: Eighty two individuals (male/female, aged: 24-70 years) were enrolled from District Sialkot (Pakistan). Two doses of Sinopharm or Sinovac COVID-19 vaccine were administered to each participant before blood sampling. The quantity of COVID-19 spike immunoglobulin G against SARS-CoV-2 (5-Antigen) was detected in serum using chemiluminescence immunoassay technique [threshold titer: 7.1 (detection), 105. 63 (seroprotection), 492.96 BAU/mL (strong humoral response)]. Results: Overall, 96.3% seropositivity, 89% seroprotection, and 37.8% (n = 31) weak immune response were recorded. Whereas, mean antibody titer was found to be 2312.02 (range: 0.0 – 28711.74) BAU/mL. A vaccinated male had approximately 4 folds (95%CI: 1.297 – 11.504; p = .002) more likelihood of weak immune response than females. Similarly, the rate of poor immunological outcome was higher in individuals with >24.9 Kg/m2 (69.2%, n = 27) body mass index compared to ≤24.9 Kg/m2. A person with Sinopharm COVID-19 vaccine was more vulnerable to weak immune response than Sinovac vaccinated participants (RR = 2.351; 95%CI = 1.327 – 4.167; p .002; 57.6% vs. 24.5%, respectively). Co-occurrence of age (>47 years) and BMI (>24.9 Kg/m2) existed in 11 of 28 males (39.3%) with impaired immunogenicity. Conclusion: The high rate of post full vaccination weak immune response is alarming. Gender, BMI, and vaccine type were amongst the predictors for diminished humoral response.

Author Biographies

Sahibzada Syed Masood us Syed, SMC, Sialkot.

MBBS, Ph.D, Dean Research, 

Abid Ali Ranjha, Sialkot Medical College (SMC), Sialkot.

MBBS, DCH, MPH, MSc, Assistant Professor Community Medicine, 

Sidra Ghazanfer, Khawaja Muhammad Sader Medical College, Sialkot.

MBBS, M.Phil, FCPS, Assistant Professor Pathology, 

Syed Muhammad Shah Hussain Miran, Usman General Hospital, Sialkot.

MID, MSDU, Lab Demonstrator/Lecturer (Sonology), 

Syeda Zahra Najam, SMC, Sialkot.

Final Year MBBS Student, 

Syeda Kainat Fatima, SMC.

Final Year MBBS Student, 

Hassan Osman Muhmood, Colonel Sultan's Lab, Sialkot.

MBBS, M.Phil, Director 

Hamda Saqib, Imran Idrees Teaching Hospital, Sialkot.

MBBS, Post Graduate Resident Medicine,