1. Meo, S.A., Alhowikan, A.M., Al-Khlaiwi, T., Meo, I.M., Halepoto, D.M., Iqbal, M., Usmani, A.M., Hajjar, W., Ahmed, N.: Novel coronavirus 2019-nCoV: prevalence, biological and clinical characteristics comparison with SARS-CoV and MERS-CoV. Eur. Rev. Med. Pharmacol. Sci. 24, 2012–2019 (2020)
2. World Health Organization (WHO): Coronavirus disease (COVID-19) outbreak situation. https://www.who.int/emergencies/diseases/novel-coronavirus-2019. Accessed 25 Dec 2020
3. https://www.biospace.com/article/comparing-covid-19-vaccines-pfizer-biontech-moderna-astrazeneca-oxford-j-and-j-russia-s-sputnik-v/
4. Meo, S.A., Abukhalaf, A.A., Alomar, A.A., Sattar, K., Klonoff, D.C.: COVID-19 pandemic: impact of quarantine on medical students’ mental wellbeing and learning behaviors. Pak. J. Med. Sci. 36, S43–S48 (2020)
5. US Food and Drug Administration: Pfizer-BioNTech COVID-19 vaccine. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/pfizer-biontech-covid-19-vaccine. Accessed 24 Dec 2020