BACKGROUND: The ABO blood group has long been recognized as a significant factor influencing susceptibility to infectious diseases. Numerous studies have explored the links between ABO blood types and both the likelihood of contracting COVID-19 and the severity of the infection, yielding conflicting results.
OBJECTIVE: This study intends to determine the influence of age, gender, the ABO blood group, and Rh factor on the potential development of COVID-19 infection.
METHODS: A cross-sectional, observational study collected data including age, gender, the ABO blood group, and Rh factor from 80 healthcare professionals at R. R. Dental College and Hospital in Udaipur with a positive history of COVID-19 infection via Google Forms (Google LLC, Mountain View, California, United States). Chi-square statistics assessed the distribution of blood types and antibodies within the samples. Odds ratio (OR) assays were used to assess the probability of a certain blood type or Rh factor with version 21.0 of the IBM Statistical Package for Social Sciences (SPSS) for Windows (IBM Corp, Armonk, NY).
RESULTS: In this study, the blood group type O was 45.2% (n = 33), type A was 21.9% (n = 16), type B was 24.7% (n = 18), and type AB was 8.2% (n = 6). Rh-positive samples were 87.7% (n = 64) and Rh-negative samples were 12.3% (n = 9). There was a statistically significant correlation between Type A (p = 0.001) and Type O (p = 0.049). Thirty-one participants (42.5%) were aged 20-30 years, 26 (35.6%) were aged 31-40 years, and 16 (21.9%) were aged 41-50 years. The statistical analysis revealed no statistically significant distinction among the age groups (p > 0.05).
CONCLUSIONS: The patients\' gender, age, and concurrent disorders are crucial risk variables that determine the severity of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection. There is growing data indicating that the ABO blood group has a significant role in disease biology at physiological and biochemical levels. Hence, this study adds valuable information to strengthen and establish the potential role of factors, such as age and gender, in the possible pathogenicity of COVID-19 infection.

Aim To estimate the ABO blood groups from saliva samples and to correlate with the secretor status. Materials and methods A sample size of 300 individuals was selected from the outpatient department of Surendera Dental College & Research Institute, Sriganganagar, India, and from dental camps organized by the college in the near vicinity. Informed consent was obtained from selected individuals to collect their blood and saliva samples. Salivary samples were evaluated for ABO blood groups by the absorption-inhibition method. The indicator erythrocytes were prepared after blood group confirmation from serum. It was used to identify the blood group antigens in saliva to confirm the secretor status. The results were tabulated and the Pearson\'s chi-squared test was performed for statistical analysis using SPSS 15.0 (SPSS Inc., Chicago, IL). Results The present study showed that 282 subjects (94%) were Rhesus positive and 18 subjects (6%) were Rhesus negative. Two-hundred-and-fifty subjects (83.3%) were secretors of antigens in saliva. Non-secretors were 50 subjects (16.7%). We identified that 250/300 were secretors and the majority were in AB & A group. Conclusion Blood groups could not be detected from the saliva of subjects who were non-secretors. In contrast, blood types could be accurately identified from the saliva of those subjects who were secretors of antigen.

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.1.