Letter to the editor : Unknown sources of COVID-19

COVID-19 outbreak has occurred all around the world for more than ten months. This is still not finished and unstable yet up to the present. The World Health Organization (WHO) estimated that about a tenth of the world’s population has been infected with COVID-19. Why so many people infected and its cases are asymptomatic? Where are the unknown sources of COVID-19 come from? Does it find and identify? The government from different countries implements several public health policies including (1) Social distance rule maintains and delays the spread of COVID-19. It''s safest to avoid crowded places, limit the number of people in gatherings, and keep a distance of at least 1 m from others for preventing cross-infection as the transmission of SARS-CoV-2 is human-to-human transmission in direct contact and droplets within 2 meters. (2) Personal protection equipment, e.g. face mask and alcohol-based hand sanitizers. Face mask reduces the spread of the virus from people coughs, sneezes, and speaking, also prevent who are contagious and have no symptoms, or are yet to develop them. Alcohol-based hand sanitizers help to avoid getting sick and spreading germs from others. It kills 99.9% of the germ on hands 30 seconds but at least 60% purity of alcohol. Hands washing with water and soap are much better because alcohol-based hand sanitizers can’t remove other types of germs, e.g. Cryptosporidium, Norovirus, and Clostridium difficile.