Background: Different studies in worldwide showed conflicting results on association of Blood groups on SARS Cov-2 infection.

Objective:  To observe the association of ABO blood groups on the presentation and outcomes of confirmed COVID -19 cases.

Design, Setting, and Participants: This was a Prospective cohort study of the patients with mild to moderately severe COVID -19 infections, presented in the COVID-19 unit of Dhaka Medical College Hospital. Participants were enrolled from 01 June to 25 august, 2020. Patient were followed up for at least 30 days after the onset of the disease. For the estimation we grouped A positive and A negative blood group into group-1 and other blood groups into group II.

Results: Total 438 patients were included in the cohort, 52 patients lost to follow up, 5 died and 381 patients completed the study. Prevalence of Blood group A [144(32.9 %)] was significantly higher among COVID-19 patients than the general population (p < 0.001).The Presenting age [{mean (SD)] of group I [42.1(14.5)] was higher than group II [38.8(12.4), p=0.014]. The gender  (p=0.23) and co-morbidity (hypertension p=0.34, diabetes p=0.13) did not differ between the patients with group I and group II. Regarding Important Presenting symptoms, Fever (p=0.72), cough (p=0.69) and Respiratory distress (p=0.09), no difference were observed. There was no significant difference regarding the median duration of symptoms in group I 12(9-16)] days and group II [12 (8-15)], (HR, 95% CI,1.14 (0.91-1.41, p=0.25), conversion to next level of severity in group I 26 (20.6%) and in group II 36 (13.8%)  (RR, 95%CI- 1.49 (0.94 - 2.35), p=0.09) and development of post COVD symptoms in group I 65 (51.6%) and in group II 107(41.1 %), (RR, 95%CI- 1.25 (1.00 - 1.57), p=0.05). But the persistent positivity of RT-PCR at 14 days of initial positivity in group I 24 (19%) and in group II (11.1 %)  (RR, 95%CI-1.71 (1.04 - 2.81), p=0.04) was higher among the patients in group I.  

Conclusions:  Prevalence of blood group A was higher among COVID-19 patients. ABO blood group has no association with the presentation and recovery period of COVID-19. But patients with blood group-A had delayed sero conversion.

Materials and methods

This single centered prospective Cohort study was conducted to evaluate the association of ABO blood groups on the presentation and outcomes of Confirmed COVID -19 infection in hospitalized and outdoor patients with COVID-19 infection. The outcomes in this research included-1. Duration required for the clinical improvement, as defined below. b. Proportion of the patients converted to next level of severity. C. Proportion of the patient remain positive for RT-PCR of COVID-19 at day 14 day after initial positivity.  d. Development of the post COVID syndrome as defined below. Participants were enrolled from 01 June to 25 august, 2020. The study was conducted in department of Medicine, Dhaka Medical College Hospital. The recruitment was limited to patients who were more than 18 years of age, with confirmed COVID-19 (RT-PCR positive) infection. Patients with haemoglobinopathies or other blood disorders were excluded from the study. Written informed consent was obtained from all the patient. Ethical approval taken from ethical review committee of the institute. Capacity to provide consent was determined by the investigators in presence of an attendant of the patient and a testimony of the attendant was obtained in the consent form and ethical review committee approved this consenting procedure during the approval of the protocol. Those who are minor, or unable to provide consent were excluded from the study. For the estimation we grouped A positive and A negative blood group into group-1 and other blood groups like B, AB and O irrespective of their Rh status into group II. An assumption was made that the expected proportions to cure from COVID-19 by day-12 in group-1(blood group A) and group-2 (blood group B, O, AB) are 0.70 and 0.90 respectively. Thus we need a total of 378 samples at 1:2 ratio, and, that would provide a power of at least 90% at two tailed test where p value less than 0.05 to detect significant difference between the groups. Considering 10% dropout, we need 416 samples in total.

Procedure

A case record form was constructed to collect base line information like demography, blood groups, clinical signs and symptoms, comorbidities, oxygen saturation. Routine investigations, which included CBC, ESR, CRP, Creatinine, RBS, SGPT, chest x-ray, D- Dimer were advised on the enrollment. Real-time-polymerase chain reaction testing for COVID-19 was done 14 days after the initial positive test on all patients. Patients were followed up directly or over telephone for at least 3 days interval up to 30 days from the onset of the disease. The patient was considered clinically improved as described by WHO and Bangladesh guideline’s [17, 18] improvement criteria. Which means body temperature remained normal for at least 3 days, respiratory symptoms were significantly improved (respiratory rate < 25 and no dyspnea) and SpO2 >93% without assisted oxygen inhalation. Mild disease was defined as the symptoms of an upper respiratory tract viral infection, including mild fever, cough (dry), sore throat, nasal congestion, malaise, headache, muscle pain, anosmia or malaise. Moderate disease as Respiratory symptoms such as cough and shortness of breath are present without signs of severe pneumonia. Severe disease as severe dyspnea, tachypnea (> 30 breaths/min), and hypoxia (SpO2 < 90% on room air). This classifications were made according to the World Health Organization and the national guideline of Bangladesh [17, 18]. In this study we assessed proportion of the patients having early recovery (clinical improvement within 7 days of symptom onset), late recovery (clinical improvement required ≥12 days), severity conversion (Patients progresses to more serious disease), persistently positive for RT-PCR of COVID-19 (have positive RT-PCR on 14 day test) and post COVID syndrome (in the absence of any definition we defined it as 1. Persistence of illness signs symptoms beyond the virologic clearance. 2. New development of symptoms within 1 month after initial clinical and virologic cure, the etiology of which postulated to be viral infection).

It is in SPSS format. there is 52 lost to follow up patients.