Then do not overdose. Tell people to take 1000IE per day, not more. This will have no negative impact on the health or economy, but if we are lucky, it will help reduce the impact of COVID-19.
Shutting down the economy is clearly dangerous, yet enough people do not seem to have a problem with that.
Vitamin D pills is just a quick fix. Moderate exercise and fresh air would probably save more lives. Healthy vitamin levels are good, but its many little things which affects health.