Compared with the feudal system under the rule of the czars, the communist government

established a command economy  

Explanation:

The feudal economy was mainly based on agriculture. There were coins in the Middle Ages, but they were little used. Product and commodity exchanges were common in feudal economy. The fief was the economic base of that period, for who had the land had more power.

This type of economy was maintained in the government of the Czars in Russia. However, when a communist government was established in that country, the economy adopted was a command economy.

Command economy is an economic model in which the state controls the economy in the country, in this case the vast majority of existing enterprises are state owned, ie state properties.

porter is writing economic history because he is focusing on the cost of developing vaccines.