Background Optimized symptom-based COVID-19 case definitions that guide public health surveillance and individual patient management in the community may assist pandemic control. Methods We assessed diagnostic performance of existing cases definitions (e.g. influenza-like illness, COVID-like illness) using symptoms reported from 185 household contacts to a PCR-confirmed case of COVID-19 in Wisconsin and Utah, United States. We stratified analyses between adults and children. We also constructed novel case definitions for comparison. Results Existing COVID-19 case definitions generally showed high sensitivity (86–96%) but low positive predictive value (PPV) (36–49%; F-1 score 52–63) in this community cohort. Top performing novel symptom combinations included taste or smell dysfunction and improved the balance of sensitivity and PPV (F-1 score 78–80). Performance indicators were generally lower for children (< 18 years of age). Conclusions Existing COVID-19 case definitions appropriately screened in household contacts with COVID-19. Novel symptom combinations incorporating taste or smell dysfunction as a primary component improved accuracy. Case definitions tailored for children versus adults should be further explored. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-021-11683-y.