Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS–CoV–2), a fast spreading and disastrous global pandemic. We have studied changes in haematology parameters in COVID-19 infected patients.

Objective/Aim: To assess haematological Parameters in COVID positive cases and analyse difference in profile of haematological parameters between categories of COVID positive cases.

Methods: This is a laboratory observation retrospective study. All COVID RT-PCR (Real Time Polymerase Chain Reaction) Positive cases from June 2020toMay 2022was considered for the study. The haematology parameters of cases including blood group and ESR were captured from hospital records and analysed for the difference between mild (Category A), moderate (Category B) and severe cases (Category C). Statistical analysis was done using SPSS software version 22. p value less than 0.05 was considered statistically significant.

Results: Total WBC count, absolute neutrophil count (ANC), absolute lymphocyte count (ALC), absolute eosinophil count (AEC), absolute monocyte count (AMC), platelet count, neutrophil lymphocyte ratio (NLR), monocyte lymphocyte ratio (MLR), eosinophil lymphocyte ratio (ELR) and platelet lymphocyte ratio (PLR) between the three categories of cases were statistically significant. The commonest blood group was O positive and majority of O positive cases were in Category C. 81.9% cases tested for ESR showed raised ESR.

Conclusion: Haematology parameters can be considered to predict progression of the disease and assess prognosis in COVID-19 infection. Total WBC count, ANC, ALC, AEC, AMC, platelet count, NLR, MLR, ELR and PLR can be considered while monitoring COVID-19 cases.