As a part of mitigation strategies during a COVID-19 pandemic, the WHO currently recommends social distancing measures through school closures (SC) and work closures (WC) to control the infection spread and reduce the illness attack rate. Focusing on the use of administrative and secondary data, this study aimed to estimate the costs and effects of alternative strategies for mitigating the COVID-19 pandemic in Jakarta, Indonesia, by comparing the baseline (no intervention) with SC + WC for 2, 4, and 8 weeks as respective scenarios. A modified Susceptible-Exposed-Infected-Recovered (SEIR) compartmental model accounting for the spread of infection during the latent period was applied by taking into account a 1-year time horizon. To estimate the total pandemic cost of all scenarios, we took into account the cost of healthcare, SC, and productivity loss due to WC and illness. Next to costs, averted deaths were considered as the effect measure. In comparison with the baseline, the result showed that total savings in scenarios of SC + WC for 2, 4, and 8 weeks would be approximately $24 billion, $25 billion, and $34 billion, respectively. In addition, increasing the duration of SC and WC would increase the number of averted deaths. Scenarios of SC + WC for 2, 4, and 8 weeks would result in approximately 159,075, 173,963, and 250,842 averted deaths, respectively. A sensitivity analysis showed that the wage per day, infectious period, basic reproduction number, incubation period, and case fatality rate were found to be the most influential parameters affecting the savings and number of averted deaths. It can be concluded that all the mitigation scenarios were considered to be cost-saving, and increasing the duration of SC and WC would increase both the savings and the number of averted deaths.