From pages 32-36 of Max Brook's World War Z
The Warbrunn-Knight Report was a threat assessment of the danger posed by the viral outbreak and a pandemic of the un dead. It was also a series of suggestions to civil and military authorities to prepare them for the inevitable mass outbreak. It bears the name of its authors: a Mossad analyst and a retired CIA Intelligence analyst that had been cooperating since the Cold War.
The report stated that over the winter, the U.S. should build up its defenses and mobilize commando teams to deal with the limited winter zombies. Come spring the main U.S. army would be mobilized to fight the larger outbreak.
Israel acted on the report and went into a self-imposed state of quarantine, though this started a civil war.
The United States chose to ignore the report because it didn't like the idea of mobilizing the army so soon after several recent wars; this eventually led to the loss of the eastern two-thirds of the country when the zombie epidemic spiralled out of control the following year.
The sad truth about the Warbrunn-Knight Report is that it never reached most of the people that should have seen it because of the secrecy that most governments placed around any knowledge of the outbreak.
Ironically, months later when the rising frequency of zombie attacks resulted in the US Joint Chiefs of Staff finally debating what to do about a hypothetical "zombie virus", their outlined response plan was essentially the same as the course of action suggested in the Warbrunn-Knight report. However, vital months of preparation time had already been lost and "Phase 2", mobilizing the regular military up to full wartime levels, was never seriously considered.