People who have already contracted COVID-19 and recovered from it are less likely to contract the disease again because of the immunity they have developed. However, a 2020 study published in the The Lancet suggests that those rare individuals who do contract the disease twice appear to experience worse symptoms the second time around. Using the thinking principles from this chapter and the fact that, because of limited testing, not all cases of COVID-19 are detected, provide an account of why this phenomenon might occur even if there is no biological mechanism that makes a second case of COVID-19 worse than a first case. Should this make you skeptical of the claim that people tend to experience worse symptoms when they contract the disease a second time?