U.S. health officials announced early in December that this year’s influenza season had started early and they predicted it would hit hard. Unfortunately, as reports from around the country make clear, they were right.

The flu began spreading on the East Coast by early November and soon worked its way west across the country. On January 9, New York City Health Commissioner Thomas A. Farley asked residents with flu symptoms to call their primary doctor first before traveling to the city’s already crowded emergency rooms. Then Boston declared a public health emergency because physicians there were reporting a ten-fold increase in the number of flu cases, compared to last year’s much milder flu season.

FluView, Influenza map, CDC

Public health officials at the Centers for Disease Control and Prevention (CDC) emphasized that the outbreak has not yet peaked and that anyone who was not yet vaccinated could still benefit from getting this season’s flu shot. Although it takes two weeks for a person to get the full benefits, the vaccine offers some degree of protection long before then. The flu vaccine is about 60 percent effective, but even people who come down with the flu after having been vaccinated are less likely to need to be hospitalized.

This year’s vaccine is considered well-matched against the flu because it contains both the H3N2 strain that is predominant this year, as well as the H1N1 strain that has been circulating in smaller numbers.

The last time the flu season started this early was in the winter of 2003-2004.

Interestingly, the type of flu that predominated then as now was the H3N2 strain. Health officials estimate that this strain causes more severe illness because young people in particular have had less exposure to it. They also note that the flu hit before many people had a chance to get vaccinated.

Other than vaccination, the best defense against catching the flu is to wash your hands regularly (or use a hand sanitizer), cover your cough and stay home if you get sick to avoid spreading the highly contagious virus to co-workers or people in hospitals and nursing homes.