2015-2016 Flu Season: Everything You Need to Know So Far

Although anyone can become infected with influenza at any time of year, the season typically spans from October to May and peaks in February. The 2015-2016 flu season started off slow but diagnoses have become more prominent and 10% of cases were confirmed during the first week of February.

During the current season, flu activity remained low overall in most parts of the United States from October to mid-December 2015. However, flu activity picked up at the end of December and continues to steadily increase through February.

“Although vaccine effective estimates are not yet available for the 2015-16 Northern Hemisphere vaccine, laboratory data to date have indicated similarity between circulating viruses and recommended vaccine components,” explained a report from the Centers for Disease Control and Prevention (CDC).

The infection remains a nationwide illness as officials in all 50 states, as well as the District of Columbia and Puerto Rico, have reported positive influenza cases. Seven states and Puerto Rico had widespread influenza activity for the week ending on February 6 — Arizona, California, Connecticut, Iowa, Kentucky, Massachusetts, and New York.

A total of 279,056 respiratory specimens for flu viruses were collected from clinical laboratories in the US from October 4, 2015 to February 6, 2016. Of those, 7,966 samples (2.9%) were positive and 1,563 of them were identified in the week ending in February 6.

Fortunately, most of the viruses identified are similar to the vaccine strains that were recommended for this season. Influenza A viruses have been the most prominent — H3N2 from October to early December and H1N1 from mid-December to early February – when compared to influenza B viruses (73% vs 27%, respectively).

Findings were similar in public health laboratory settings where 26,287 respiratory specimens were tested and 3,529 came back positive for the infection. Influenza A viruses were more prominent than influenza B viruses (75% vs. 25%, respectively).

During the last week of 2015, a patient in New Jersey was infected with an influenza A (H3N2) variant (H3N2v) virus — which causes the swine flu. However, unlike the pandemic H1N1 swine flu outbreak in 2009, the patient was not hospitalized and fully recovered. There were three total H3N2v cases in 2015.

The CDC continues to remind the public that vaccination is the best way to prevent the flu and other complications it may bring along with it. Anyone over the age of six months, unless otherwise specified, should receive a flu shot every year.