The rising number of COVID-19 all around the world caused a drastic increase in theoccupancy rate of healthcare facilities, triggering overload in some places. This situationrequires healthcare workers to evaluate patients’ conditions and conduct risk stratificationefficiently, especially in a triage situation. Complete blood count is a widely available,economically affordable, and time-efficient testing method which may be significant in assistingthose processes. This review article analyzes changes in complete blood count parameters inCOVID-19 with the aim to identify the common changes in the parameters in COVID-19 patientsand their relation to the disease progression and severity. COVID-19 patients commonlyexperienced anemia, increased red blood cell distribution width, decreased white blood cellcount, significant changes in white blood cell differential count, and thrombocytopenia. It isunderstood that changes in complete blood count parameters and their extent may providevaluable information about the disease severity and prognosis. In conclusion, COVID-19 patientsshare a common pattern of complete blood count parameters alterations which is related to thedisease progression, severity and prognosis. It is expected that complete blood count examinationmay play a major role in COVID-19 management, given the valuable information provided bythe examination.Keywords: complete blood count; COVID-19; erythrocyte; leukocyte; platelet

Background The number of diphtheria cases recently increased, such that an outbreak was declared in East Java Province, which includes the Sampang District. Immunization completion status is a determining factor for diptheria infection. Objective To investigate for correlations between immunization status and outcomes (severity level, fatality, and complications) of diphtheria patients in the Sampang District. Methods This analytic, cross-sectional study used secondary data from the East Java Provincial Health Office on diphteria patients aged 0-20 years during the 2011-2015 outbreak in the Sampang District and interviews with diphtheria patients in that region. The Diphtheria Research Team of Soetomo Hospital collected data on immunization status, diphtheria severity (mild, moderate, or severe), case fatality (died or survived), and complications in the patients (with or without complications). Spearman’s, Chi-square, and Fisher’s exact tests were used for data analyses, accordingly. Results Seventy-one patients with clinical diphtheria were identified, 17 of whom were confirmed with positive culture results. The case fatality rates were 7% in patients with clinical and 5.9% in confirmed diphtheria. There were no correlations between patient immunization status and severity (P=0.469 clinical, P=0.610 confirmed), or fatality (P=0.618 clinical, P=0.294 confirmed) of diphtheria in the clinical and confirmed diphtheria patients. However, there was a correlation between patient immunization status and the emergence of complications in clinical (P=0.013), but not in confirmed (P=0.620) diphtheria patients. Conclusion There is a correlation between immunization status and complications in clinical diphtheria patients. Such a correlation is not found in confirmed diphtheria cases because none of the patients had complete immunization status.