INTRODUCTION
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a new strain of coronavirus which was initially unknown until its outbreak in Wuhan, China last December 2019, and it has been declared as a Public Health Emergency of International Concern by the World Health Organization.1 In the Philippines, the total number of positive COVID-19 cases has risen to more than 65,000 Filipino by mid July 2020, and it continuously rose to more than 4ยท10 million cases by June 2023.2
As the COVID-19 pandemic spreads worldwide and the number of affected individuals rises, the healthcare system of the Philippines has been greatly challenged,3 making the identification of individuals at greatest risk a key challenge.4Cognizant of the significant mortality and morbidity associated with COVID-19, scientific interest in identifying the characteristics which increases susceptibility to the disease and factors which determine its progression, severity, and prognosis has increased.5-7
One of the characteristics that has recently gained scientific interest is the association of the ABO blood type with COVID-19 infection susceptibility. It is hypothesized that the ABO carbohydrate moieties are genetically inherited, and it is associated with certain conditions and diseases such as cardiovascular diseases, cancer, and certain infections, including coronavirus infections.4,7,8With the increasing number of COVID-19 cases and the increasing scientific interest in the association of ABO blood type and COVID-19 susceptibility and outcomes, it is imperative to determine this association among Filipino patients. This knowledge can help medical professionals further determine the relative risk of specific Filipino subpopulations for COVID-19 and its outcomes. This study determined the relative risk of COVID-19 infection and disease outcomes (ICU admission, intubation, and mortality) with ABO blood type among the hospitalized Filipino patients from select tertiary hospitals in Metro Manila, Philippines.