Effectiveness of the pre-Omicron COVID-19 vaccines against Omicron in reducing infection, hospitalization, severity, and mortality compared to Delta and other variants: A systemati... oleh Pradipta Paul, Ahmed El-Naas, Omar Hamad, Mohammad A. Salameh, Nada Mhaimeed, Ibrahim Laswi, Ali A. Abdelati, Jamal AlAnni, Bushra Khanjar, Dana Al-Ali, Krishnadev V. Pillai, Abdallah Elshafeey, Hasan Alroobi, Zain Burney, Omar Mhaimeed, Mohammad Bhatti, Pratyaksha Sinha, Muna Almasri, Ahmed Aly, Khalifa Bshesh, Reem Chamseddine, Omar Khalil, Ashton D’Souza, Thanu Shree, Narjis Mhaimeed, Lina Yagan, Dalia Zakaria