We know from records left by these civilization and the research of historians who bring these records to the present day.
Diseases pose a terrible threat to every human being. Some are mild, but others may even kill millions - as has already happened - spreading to large parts of the world. For many centuries it was not known what produced the plagues and the great epidemics: a divine punishment? an astrological conjunction? a climate change? It took a long way to understand the cause of communicable diseases and how to prevent them.
All this way was recorded by doctors, healers and other health professionals of ancient civilizations, these records show us how people of this time treated and prevented infectious diseases. Although we now know that many of the techniques used by these people are inefficient today, but many of these records have been effective for today's medicine.
Public health policies and government regulations are the basis of good health and disease prevention fo the public.
First of all, if we create public health policies and government regulations that allow people who possibly cannot afford their medications to get them for reduced price or free, we can increase the amount of people who have good health and aren't prone to diseases.
Government regulations can also help people who are well off, too. If we put government regulations and policies in place promoting good health habits like washing your hands often even with the CDC, we would be able to show the public the benefits of good health.
Thus, using government regulations and health policies can help anyone and give support and reasons to the general public to maintain good health.
Hope this helps
Vaccines can be described as drugs, or medication, since that's pretty much what it is. I'm sorry if I sound a little vague, but I don't know much about this