Without social distancing, quarantine, or other measures, a virus like COVID-19 can spread rapidly through the population. COVID-19 spreads most easily between people within close distances via droplets in the air created while coughing, sneezing, or talking. People can become contagious before their symptoms appear, or they may never develop symptoms, so it is possible to transmit the disease without a person realizing they are infected. If the virus is allowed to spread too quickly, it can overwhelm the capacity of healthcare services, resulting in less access to treatment and a higher rate of deaths.