After the first lockdowns in response to the COVID-19 outbreak, many countries faced difficulties in balancing infection control with economics. Because there was limited prior knowledge, economists began researching this issue using cost-benefit analysis and found that infection control processes significantly affect economic efficiency. Rowthorn and Maciejowski used economic parameters in the United Kingdom to numerically demonstrate that an optimal balance was found in the process, including keeping the infected population stationary. However, universally applicable knowledge, which is indispensable for guiding principles of infection control, has not yet been developed because these analyses assume regional parameters and a specific disease. Here, we prove the universal result of economic irreversibility, which means that delaying infection control measures is more expensive than implementing infection control measures early while keeping infected populations stationary. This means that once the infected population increases, society cannot return to its previous state without extra expenditures. This universal result is analytically obtained by focusing on the infection-spreading phase of pandemics, which is not only applicable to COVID-19, and whether or not `herd immunity' exists. It also confirms the numerical observation of stationary infected populations in its optimally efficient process. Our findings suggest that economic irreversibility is a guiding principle for balancing infection control with economic effects.