The strain represents some 90 percent of detected cases of influenza in the country, the health ministry said in a statement.
The number of cases reported was up sharply from Thursday, when health officials said 333 had been identified. Authorities have brushed aside suggestions of a new health emergency but have begun tracking new cases since December 2011.
The first outbreak of the A(H1N1) virus occurred in April, 2009 in Mexico and the United States, and quickly became a global pandemic that claimed the lives of 17,000 people. In Mexico alone, more than 1,250 people died.
The World Health Organization declared the pandemic over in 2010 as the flu returned to typical seasonal patterns.