COVID-19 vaccination is an important tool to help stop the COVID-19 pandemic. Wearing masks indoors and in crowded outdoor spaces helps to reduce your chance of being exposed to the virus or spreading it to others, but these measures are difficult to maintain for long periods of time. Vaccines work with your immune system so it will be ready to. COVID-19 is a respiratory illness caused by a novel (new) coronavirus designated SARS-CoV-2 that spreads person to person. COVID-19 can cause mild to severe illness. Some people have little to no symptoms; many have mild disease, but can spread it to others. Severe illness typically, though not always, occurs in older adults or in those with.