Modern society collapsed as a result of the Plagues huge death toll and the break down of essential services. As the death toll mounted amoung both medical personnel and the rest of the population, health care workers fled the hospitals. This was especially pronounced in the populous but poor Third World cities.
Many people fled the cities and government broke down.
The plague was most noticeable in large urban areas of the First World at first. It quickly spread to the Third World though.
Many First World countries such as the United States, France, England and such broke down into smaller regional governments. Central governments had proven unable to provide significant assistance to people, whereas more local efforts were noticable. Many of the local efforts were done by local divisions of national governments, but inter-region assistance was sparse and often not wanted for fear of contagion.
Most Third World countries also broke down into smaller political units. Unlike the First World, most of the break downs were violent and ended with huge casualties.
Many medical facilities were destroyed in riots. Disease runs rampant in many urban areas due to lack of saniation facilities, dead bodies and such.
As the plague spread, all commerce ground to a halt. Ships were not permitted to enter port other than to anchor. Air travel was shut down entirely. Passenger trains and buses were shut down along with other means of local and long-distance travel. All countries tried to impose quarintines, both to keep foreigners out, but also to keep their existing populations in place. Tax collection become very problematic. Many people were dead, both collectors and citizens. Many people attempted to scam their deaths to avoid taxes.
General business depression. Wage and price controls were instituted early on to prevent speculation, especially in food and basic goods. Overall economic activity declines as buyers die, it becomes harder to transport goods across quarintine zones. There is a lack of workers in many areas since many of them have died. A lot of the remaining population has the "wrong" skills for jobs that need to be done.
Notes: local leaders such as preachers, ambitious politicians and gang leaders started taking over parts of their local areas. Rioting in the cities could not be contained. Troops were more interested in protecting areas from the spread of the Plague than in putting down riots. They could ignore small sections of a city and preserve the much larger and richer areas. Defiance of the central government started occuring both in the US and in other parts of the world.
Initially the quarintines shut down all but the most essential industries. Much industry was lost in fires and lack of upkeep during the plague years.
Technology has basically been frozen at, or dropped from the level of when the plague started. With the loss of about 60% of the world's population many societies are to involved in surviving and rebuilding to invest in research and development. While the actual knowledge of how high tech things are has not been lost, many factories and skilled personnell have been lost. Alternatively, many times workers are needed for more survival oriented jobs than high tech consumer goods.
Communications fails fairly quickly. The telephone and internet (if present) will not run for long without at least basic upkeep.
With the loss of most sources of motor vehicle fuel and modern fertilizers, food production has dropped to 1800's level of production and distribution. Gone are the days of milking cows in up state New York for consumption in New York City.
The military was called out fairly early on after the 3rd wave of people started dying. At first it was just the National Guard and local Army Reserve and Marine Corp Reserve units that were called out. Regular Army and Marine Corp units only took on duties near their local bases. Countries that had troops overseas tried to call them back. Some, like the US and Canada succeded using their own transports.
Most UN Peacekeepers were stranded. The local warring factions realized fairly quickly that the UN forces were abandoned and would not be getting resupplied. Some UN contingints were able to set themselves up as the new power, but usually they were just killed. Civil wars broke out when they realized that there would no longer be outside assistance to supply weapons nor to stop the fighting.
As the Plague spread, and casualties grew, all military personnel were called up. This included all retirees and former members who had at least a good conduct discharge. Also, all military units that were overseas were brought back to the US. The military was retooled towards a much more defensive posture and internal security stance. Deep ocean navy units were de-emphasized and heavy armor units were mothballed. Most new units were heavy on light armor vehicles, infantry and similar. Local and state governments recruit lots of police and national guard to enforce quarintines and prevent looting.
As the budget for supporting troops dwindled, troops had to strike out on their own. This is similar to what happened in the late 1990's in the former Soviet Union.
To The Disintegration of the United States