A study published in Science recently gave information about different forms of immunity over time after infection with COVID-19. Most people infected with COVID-19 will continue to be immune to it for a long time with few exceptions. There is a possibility that over time, people given the vaccine will be able to get infected (following exposure to an infected person) with a form of COVID-19 limited to only the upper respiratory tract. The quickest and safest way to eliminate the threat of this virus is to have as many people as possible get vaccinated.
