ABSTRACT
Background and Aims: COVID-19 morbidity and mortality varied globally through the pandemic. We studied the relationship of SARS-CoV-2 variants of concern (VOC) with COVID-19 severity and mortality among hospitalized patients in Pakistan. Methods: A retrospective review of clinical, laboratory, and vaccination data of 197 COVID-19 adult patients at the Aga Khan University Hospital, Karachi between April 2021, and February 2022 was performed. SARS-CoV-2 VOC identified in respiratory samples were analyzed. Univariate and multivariate analysis was conducted to identify factors associated with COVID-19 outcomes. Results: The median age of cases was 55 years and 51.8% were males. Twenty-four percent of females were pregnant. Of COVID-19 cases, 48.2% had nonsevere disease, while 52.8% had severe/critical disease. Hypertension (48%) and diabetes mellitus (41%) were common comorbids. SARS-CoV-2 VOC identified comprised; Omicron (55.3%), Beta (14.7%), Alpha (13.7%), Delta (12.7%), and Gamma (3.6%) variants. Most (59.7%) study subjects were unvaccinated. Of vaccines, 88% had received inactivated virus COVID-19 vaccines. Increased risk of severe disease was associated with age ≥50 years (odds ratio [OR]: 5.73; 95% confidence interval [CI]: [2.45-13.7]), as well as with diabetes mellitus (OR: 4.24; 95% CI: [1.82-9.85]). Full vaccination (OR: 0.25; 95% CI: [0.11-0.58]) or infection with Omicron (OR: 0.42; 95% CI: [0.23-0.74]) was associated with reduced disease severity. The risk of mortality increased with age ≥50 years (OR: 5.07; 95% CI: [1.92-13.42]) and a history of myocardial infarction (OR: 5.11; 95% CI: [1.45-17.93]) whilst, infection with Omicron was found to reduce the risk (OR: 0.22; 95% CI: [0.10-0.53]). Conclusion: Our study describes the relationship between the severity of COVID-19, in-hospital mortality in relation to SARS-CoV-2 variants, and the impact of COVID-19 vaccination in Pakistan. Outcomes were more favorable in younger individuals, after vaccinations and with Omicron variant infections. Most cases received inactivated virus vaccines therefore these data highlight the protection provided against severe COVID-19.
ABSTRACT
COVID-19 resulted in extensive morbidity and mortality worldwide. SARS-CoV-2 evolved rapidly, with increasing transmission due to Variants of Concern (VOC). Identifying VOC became important but genome submissions from low-middle income countries (LMIC) remained low leading to gaps in genomic epidemiology. We demonstrate the use of a specific mutation RT-PCR based approach to identify VOC in SARS-CoV-2 positive samples through the pandemic in Pakistan. We selected 2150 SARS-CoV-2 PCR positive respiratory specimens tested between April 2021 and February 2022, at the Aga Khan University Hospital Clinical Laboratories, Karachi, Pakistan. Commercially available RT-PCR assays were used as required for mutations in Spike protein (N501Y, A570D, E484K, K417N, L452R, P681R and deletion69_70) to identify Alpha, Beta, Gamma, Delta, and Omicron variants respectively. Three pandemic waves associated with Alpha, Delta and Omicron occurred during the study period. Of the samples screened, VOC were identified in 81.7% of cases comprising mainly; Delta (37.2%), Alpha (29.8%) and Omicron (17.1%) variants. During 2021, Alpha variants were predominant in April and May; Beta and Gamma variants emerged in May and peaked in June; the Delta variant peaked in July and remained predominant until November. Omicron (BA.1) emerged in December 2021 and remained predominant until February 2022. The CT values of Alpha, Beta, Gamma and Delta were all significantly higher than that of Omicron variants (p<0.0001). We observed VOC through the pandemic waves using spike mutation specific RT-PCR assays. We show the spike mutation specific RT-PCR assay is a rapid, low-cost and adaptable for the identification of VOC as an adjunct approach to NGS to effectively inform the public health response. Further, by associating the VOC with CT values of its diagnostic PCR we gain information regarding the viral load of samples and therefore the level of transmission and disease severity in the population.
