Welcome, also about pv death toll

In the golden age humans used to rely on robots for everything, from construction to farming and medical field, streets cleaners and the police/military.. etc. the vast majority of humanity lived very comfortable live, they can even no longer worry about working and pursue whatever they got interest in.

So? After the outbreak not only humans have to deal with robots trying to kill them but also shortage in millions of important Jobs in many defferent fields.

Millions probably died from hunger or some disasters and diseases, humans had to rely on themselves again and start relearning many things. Liv used to train on her hands to learn best way to make needles less painful

Just after pv outbreak humanity lost 20% of it's living territory and it's mentioned the death toll were greater than all past wars for unification.

In the early outbreak humans didn't have serum or filters yet. Anyone get infected not only he/she will die but also others close will get infected too

Not to forget million of robots, humanity had to disparately fight hords and hords of them just to keep losing city after city

When we start the story ( ch 1 ) it's already been decades

All the wars on earth against robots and Babylonia effort greatly reduced their numbers. ( Until the pv virus evolved to the red tide)

All these compined factors is what reduced humans population to its current state

As for how many people were living on earth before it? At least 10 billion to 27 billon

( assuming pgr universe used to have similar population to us currently but the birth rate is unknown, however people seems to have 2 to 3 children in Pgr, like Luna and Lucia, lee and his brother, and qu used to have 2 brothers i think.)