Methods

This descriptive cross-sectional study was approved by the Khyber Medical University (KMU) Ethical Committee. Due to retrospective nature of our analysis, we were granted a waiver from obtaining informed consent.

In KP, testing has been extended to symptomatic and suspected cases, those presenting at hospitals, people identified through contact tracing, contacts of confirmed cases, people with travel history, or anyone using the free COVID-19 response hotline. Samples are sent to one of the 28 public and private sector diagnostic laboratories, serving all regions of KP province, which has a population of 35.53 million people. This network of laboratories is regulated by the provincial health department, and all SARS-CoV-2 viral RNA RT-PCR tests are conducted under guidelines from National Institute of Health (NIH), Islamabad. To ensure uniformity in sample processing and data analysis, all laboratories in KP are periodically assessed through an External Quality Assurance program mandated by NIH. Individual-level test results are logged onto, and maintained on a centralised contact tracing database. We extracted retrospective data for all SARS-CoV-2 RT-PCR tests carried out from March, 2020, to July, 2021, in KP. For purpose of this study, primary infection was defined as a positive RT-PCR test for SARS-CoV-2. Suspected reinfection was defined as a second positive test taken for SARS-CoV-2,≥ 90 days after the primary positive test result. Analyses were performed using MS Excel. Comparison between demographic variables of primary infections and suspected reinfections were made using Chi-square test.