Identifying emerging health misinformation is a challenge because its manner and type are often unknown. However, many social media users correct misinformation when they encounter it. From this intuition, we implemented a strategy that detects emerging health misinformation by tracking replies that seem to provide accurate information. This strategy is more efficient than keyword-based search in identifying COVID-19 misinformation about antibiotics and a cure. It also reveals the extent to which misinformation has spread on social networks.