A relative handful of Americans have received the vaccine to protect against the novel coronavirus. But according to HuffPost, it's unclear if those lucky few can still pass along the virus to others, even if they themselves aren't infected. Likewise, it's important to remember that even after getting the jab, it takes the body at least a month to build up its immunity to COVID-19. Therefore, it's essential to continue following proven public health measures, like universal masking, handwashing, and physical distancing. Experts say Americans shouldn't start to relax on observing these measures until roughly 70% of the population has been vaccinated.