OBJECTIVE: Early responses to COVID-19 have been conducted by Vietnam’s government in both the speed and the stringency of the interventions used. To evaluate the effect of these policies, we built the predictive model to compare the actual cases and estimated cases in Vietnam.

SUBJECTS AND METHODS: We applied the predictive model with two parameters at three points before the travel restriction policy, after one week, and after the policy’s end (2 weeks). After each time of evaluation, two parameters in the model were adjusted to estimate new cases in the following time. Nonlinear Least Squares determined the nonlinear (weighted) least-squares estimates of the parameters of a nonlinear model.

RESULTS: Many measures were applied to prevent the spread of the pandemic, and two highlighted measures were quarantine and social distancing policy. Parameters were estimated before the policy (a = 20.686, b = 0.098), after the promulgation of policy (a = 23.179, b = 0.089), and after one week (a = 30.759, b = 0.072). The difference between expected and observed cases was statistically significant (p = 0.01), showing positive results of the policies. After one week (the incubation period), suspected and infected cases have been detected and managed, facilitating the reduction of new cases.

CONCLUSIONS: The effects of early policy response on the COVID-19 pandemic were significant after each stage of serial measurements, according to the parameters of the predictive model. Our model can be considered in the next wave of the COVID-19 pandemic or another pandemic to predict progress and take measures effectively.