The Gallup-Healthways Well-Being Index asked 500 U.S. adults each day whether they had a cold or the flu the previous day. An average of 4.7 percent of U.S. adults reported having the flu the day before they were surveyed in January.
The previous highs each flu season included an average 3.3 percent of U.S. adults saying they had the flu "yesterday" in the month of February in the 2008-09 and 2010-11 seasons; 3.0 percent in February of the 2011-12 season; and 2.7 percent in October of the 2009-10 season -- amid the outbreak of the H1N1 flu virus -- Gallup said.
The percentage of Americans reporting they had a cold in January also reached a five-year high.
On average, 10.8 percent of U.S. adults reported having a cold on the day prior to being interviewed, up from 9.9 percent in December. The percentage of daily cold reports in January was still on par with peak months in past years.
The survey of a random sample of more than 14,759 adults was conducted Jan. 1-31. It had a margin of error of 1 percentage point.