I read this because I have received the second in the series as a free copy to review.
It is about a secret governmemt programme that trying to extend the lifespan of human beings. They had been using criminals who had been on death row, and been injecting them with this virus. They decide to try it on a younger patient, Amy, aged 6, who has been abandoned by her mother at a convent. The guys bringing her in muck up the collection. They bring her to the site and she is infected, just as it goes horribly wrong and the virus infects workers at the site, and then the population
Jump forward a number of years and humanity is holed up in enclaves, protected from the virals, as the infected beings are called, and are eeking out an existence. On a recce to the power source the members of one enclave are attacked. One guy, Peter is isolated, and Amy protects him from the virals.
The enclave is attacked, and Amy enters and joins them. They discover that there is a site that is transmitting to Amy, so a few members of the enclave decide to go to Colorado to meet those transmitting the signal. They travel across the now barren American landscape, sheltering at night, and meet with others as they travel.
This is a enormous book, almost 1000 pages, and whilst is is a fairly easy read, I felt that it took too long to get going. The action starts around 600 pages, when the pace of the narative picked up and it got better.