Children may make up a large portion of the population that are asymptomatic (no symptoms) or have only mild symptoms when infected with COVID-19. Using antibody tests on those individuals who have not had symptoms can give researchers a sense of how many people have been exposed to and infected by the virus.
In the future, antibody testing may show whether someone has immunity against COVID-19, meaning that they cannot get infected again. If the presence of antibodies represents immunity, it can help inform leaders and public health officials about whether the population has reached herd immunity. Herd immunity is when a large percentage of a population has become immune to COVID-19, which can protect those people who are not immune.