Pooling multiple samples for COVID-19 testing is a popular method to increase testing capacity. However, a new study challenges the assumption that including more than one infected sample in a pooled test does not affect the test results. The researchers found that the false-negative rate of pooled tests increases when the infection prevalence is low. This means that while pooling can be efficient for testing many people quickly, it may not be as accurate in detecting infections when there are fewer cases in the population. The study suggests being cautious with pooling and developing better testing strategies to account for potential errors.