As influenza viruses sweep much of the nation, with 43 states now contending with "widespread" cases, Hawaii is the sole state reporting only "sporadic" flu activity.

Even so, health officials in the isles are bracing for a possible surge before flu season wraps up this spring.

Deputy state epidemiologist Dr. Melissa Viray said historically, the number of flu cases in Hawaii tends to spike about a month after cases peak on the mainland, and that peak varies from year to year.

"We tend to have a delay, and should take that as an advanced warning," Viray said. "Based on what we’re seeing on the mainland, we want to make sure our population is protected."

According to the Centers for Disease Control and Prevention’s latest FluView report, during the week that ended Dec. 27, six states reported "regional" flu activity. One week earlier, California also had been in the "sporadic" category, and Alaska and Oregon experienced "local" flu outbreaks. Now all three states have been upgraded to "regional" flu activity, along with Arizona, Maine and Nevada.

Every other state is grappling with "widespread" outbreaks, according to the CDC.

At least 601 people in the U.S. died of influenza or pneumonia during the 52nd week of the year, down from 837 the previous week, according to data collected by the CDC’s 122 Cities Mortality Reporting System.

The 601 deaths accounted for 6.8 percent of the 8,893 total deaths in the last week of the year, just missing the 6.9 percent threshold to qualify as an epidemic.

Flu viruses are tied to the deaths of 21 children in the U.S. so far this season. There have been no flu-related pediatric deaths in Hawaii.

Last year, the season’s national tally for pediatric deaths was 109. During the 2012-13 season, 171 children died from the flu.

While young children and senior citizens are among the most likely groups to be hit hard by the flu, health officials warn that any age is vulnerable.

During the last flu season, people ages 18-64 represented 61 percent of all flu-related hospitalizations nationwide — a huge leap from the previous three seasons when this age group represented about 35 percent of hospitalizations.

The latest weekly influenza surveillance report released by the state Department of Health suggests that patient visits to doctors due to influenzalike illness have remained minimal compared to the rest of the nation.

According to the DOH’s FluView for the week that ended Dec. 20, 1.6 percent of Hawaii’s outpatient visits were related to patients who displayed symptoms of influenzalike illness. The national rate for that week was 5.5 percent.

Flu season in the Northern Hemisphere typically runs from October to May. And since Hawaii has seen surges of flu cases as late as May, DOH officials urge residents who have yet to get vaccinated to do so.

Viray said the current vaccine supply should be adequate as there has been no indication of a shortage in the state.

At least 69,000 vaccine doses have been administered through Kaiser Permanente Hawaii, according to spokeswoman Laura Lott.

In addition, health officials advise covering up when coughing or sneezing, and washing hands often.

Flu symptoms include fever, cough, sore throat, runny nose, headache, chills, body aches, fatigue, and possibly vomiting or diarrhea.

The Health Department directs anyone experiencing these symptoms to contact a physician and to stay at home to prevent the spread of infection.

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