Objectives: To determine association between Polymerase Chain Reaction (PCR) and antibody positivity by assessing the antibody response in PCR positive Versus PCR negative COVID-19 exposed symptomatic/ asymptomatic healthcare workers.
Methods: A Total of 102 healthcare workers (HCW) were included in this crosssectional study after written informed consent including doctors, nurses, laboratory and janitorial staff who were working in isolation ward admitted with symptomatic COVID-19 patients and their samples. Specimen swabs from posterior oropharyngeal wall and nasopharynx were taken and kept in viral transport medium to perform Polymerase Chain Reaction (PCR) testing of SARS-CoV-2 either at onset of symptoms or at 6 weeks (42 days) after first day of duty with COVID-19 patient and blood samples were drawn to measure the serum antibody response after recovery or at completion of 6 weeks (42 days) of their first duty in COVID-19 wards. Serum C- reactive protein (CRP) in mg/L was measured by immuno-turbidimetry in both groups at the time of PCR.
Results: Mean age of our study participants was 31 ± 8.9 years. Of 102 HCW, 60(58.8%) were males and 42(41.2%) were males; 42 (36.23%) were PCR positive and 60(63.76%) were PCR negative, 57(50.72%) had reactive antibodies and 45(49.28%) had non-reactive antibodies. Of 35 PCR positive subjects, 11 remained asymptomatic. There were 76% subjects who had positive PCR & reactive antibodies, 63.6% subjects with negative PCR and Non-reactive antibodies. Interestingly, (22)36.4% subjects had negative PCR but reactive antibodies. Likewise, 16.7% subjects had positive PCR but non-reactive antibodies. However, statistically moderate significant association (x2(1) =10.02; P=0.00) was found between PCR positivity and antibody positivity. Serum CRP in PCR positive and negative HCWs was 1.5 mg/L and 1 mg/L correspondingly.
Conclusion: Antibody response may be used as a screening tool for COVID-19 infection particularly in asymptomatic exposed subjects.
Muhammad Younas, Kamran Afzal, Hamid Iqbal, Asma Khan, Kainat Younas, Asma Naseer Cheema and Muskan Younas*