Hematologic and coagulation responses to Johnson & Johnson COVID-19 vaccination in the Amhara region, Ethiopia

Coronavirus disease 2019 (COVID-19) is a pandemic disease that causes serious pulmonary complications. Vaccination is the most effective measure to prevent severe illness and reduce mortality. The Johnson & Johnson vaccine is an adenovirus vector-based vaccine designed to target the spike protein of the virus. The vaccine has its own side effects, such as thrombocytopenia and coagulation alteration. Therefore, this study aims to assess changes in hematological and coagulation parameters among individuals who received the Johnson & Johnson COVID-19 vaccine in the Amhara National Regional State, Ethiopia, in 2023. A prospective longitudinal study was conducted at five comprehensive specialized hospitals, selected based on their large catchment areas in the Amhara National Regional State between May and September 2023. The study participants were selected by a systematic random sampling technique. Socio-demographic and clinical data were collected using a structured questionnaire and data collection tool. 6 mL of venous blood was collected using the vacutainer method, and the blood was analyzed for coagulation and complete blood count (CBC) profile. The data was coded and entered into EpiData 4.6 before being analyzed with SPSS version 25. The Kolmogorov-Smirnov test was used to evaluate the normality of the data. For normally distributed variables, paired t-tests were performed; for non-normally distributed data, the Wilcoxon signed-rank test was used to evaluate differences before and after vaccination. The threshold for statistical significance was fixed at p < 0.05. A total of 89 adults were included in the analysis, of whom 39 (43.8%) were female. Following vaccination, platelet counts decreased significantly from 296 ± 105.3 × 10⁹/L to 275 ± 87.2 × 10⁹/L. Statistically significant reductions were also observed in red blood cell count (P < 0.001), hematocrit (P = 0.002), and mean corpuscular hemoglobin concentration (P = 0.03). In contrast, coagulation parameters were significantly prolonged post-vaccination, with prothrombin time (PT) increasing from 16.59 ± 8.35 to 19.2 ± 4.51 s (P = 0.025) and activated partial thromboplastin time (aPTT) rising from 34.23 (IQR: 16.89) to 42.80 (IQR: 22.37) seconds (P < 0.001). The most frequently reported post-vaccination adverse events were pain at the injection site 57 (64%), headache 33 (37%), fever 29 (32.5%), and muscle pain 12 (13.5%). The present study demonstrates that the Johnson & Johnson COVID-19 vaccine can induce significant changes in hematological and coagulation parameters. Therefore, individuals who will be vaccinated with Johnson and Johnson should be critically followed for coagulation and hematological profiles. Further large-scale studies are warranted to clarify the clinical implications of these hematological and coagulation changes. Additionally, comprehensive research encompassing all COVID-19 vaccine types is needed to provide broader insights.