MONTREAL — It's official: the flu has reached epidemic levels in the United States, the US Centers for Disease Control and Prevention (CDC) said Friday.

The CDC said 7.3 percent of deaths last week were caused by pneumonia and the flu, which is above the epidemic threshold of 7.2 percent, Reuters reported.

Nine of the 10 regions of the US had “elevated” flu activity.

Influenza has spread rapidly throughout Canada and in the US, where the number of affected states increased to 47 Friday, USA Today reported, citing the CDC.

Canada has also been experiencing above-average hospital visits and increased sales of antiviral drugs. Medication shortages have even prompted the federal government to lend its supplies of Tamiflu back to its manufacturer, the Province reported.

The Centers for Disease Control and Prevention said that the percentage of people visiting hospitals has increased two-fold in the past month, CBS News reported.

Boston declared a public health emergency after over 700 cases were reported in the city. Eighteen deaths from the flu have been reported in Massachusetts, the Washington Post said.

In Illinois, 147 people were admitted to intensive care units at hospitals, and six deaths have been reported. The outbreak has been so intense that Chicago hospitals have been turning patients who aren't in severe condition away, CBS News Chicago reported.

Canada's Public Health Agency has reported 4,632 lab-confirmed cases and 127 flu outbreaks across the country, the Globe and Mail reported. However, those statistics are two weeks old and don't include cases that haven't been formally diagnosed, as the Globe and Mail pointed out.

"Reports of influenza-like-illness are nearing what have been peak levels during moderately severe seasons," Dr Joe Bresee, chief of the epidemiology and prevention branch of the CDC's influenza division, said in a statement, the Denver Post reported.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has said that this is one of the worst flu seasons in at least 10 years, WTOP.com reported. The last time flu cases were being contracted at this rate was the 2003-2004 season, when the same strain of the H3N2 influenza was being spread.

H3N2 has stronger symptoms than the usual flu, and stays in your system longer, the Atlantic Wire reported.

Though doctors say that this year's vaccine was very well-matched to the strains of flu circulating, only 32 percent of the US population was vaccinated, and the vaccines only have a 60 percent effectiveness rate.

Despite that, the vaccine supply is running low, with 128 million doses already distributed — almost 95 percent of the 135 million doses produced by manufacturers, according to the Washington Post.

"People may have to look around to find vaccine,” Thomas Skinner, a CDC spokesman, told reporters.

Joslin B. Leasca, a family nurse practitioner, and Dr. Monica L. Gross from the South County Walk-In and Primary Care clinic gave GlobalPost these 5 tips to prevent getting the flu.

1. Get a flu vaccine. Wash your hands. 2. When gathering with friends and family, stay away from people who are obviously ill. Wash your hands if you come in contact with someone who is obviously ill. Avoid everyone's respiratory secretions - a person may spread the influenza virus for several days before becoming obviously ill, and may spread the virus for 48 to 72 hours after their fever has subsided. 3. Get plenty of rest, stay well hydrated, pay attention to your nutrition. Wash your hands. 4. Exercise outdoors, not in the gym. If exercising in the gym is the only option - clean equipment before AND after using. 5. Touch surfaces in public areas as little as possible - wash your hands after contact with surfaces that you are unfamiliar with. Never touch your face before you wash your hands. Wash your hands before you eat.

Meanwhile, Google is tracking the global flu fluctuations with its' "Flu Trends" feature, which tracks where users enter "flu" or related search terms and spits out estimations about that area's spread of disease.

Right now, the map indicates "high" or "intense" flu activity throughout all of the US and Canada.

Check it out below.

More from GlobalPost: Mexico bird flu outbreak: 10 million poultry to be vaccinated against H7N3