By Morgan Jones
Many young to middle-aged adults might brush off flu season as no big concern for them. But this season, the flu has hit the young hard.
The Centers for Disease Control and Prevention (CDC) has released two new reports examining this year's flu season.
The reports show that influenza has affected a high rate of young adults, but that the flu vaccine has proven effective in preventing illness.
The two new reports, both released on February 20, took a look at different aspects of this season's flu virus.
One report, led by Carmen S. Arriola, DVM, PhD, Epidemic Intelligence Service officer with CDC, looked at flu samples from coordinating laboratories across the US from September 29, 2013 to February 8, 2014.
In total, they identified 36,619 positive flu tests, most of which were the H1N1 strain of influenza.
Using the Influenza Hospitalization Surveillance Network, Dr. Arriola and team also looked at instances of hospitalization for the flu between October 1, 2013 and February 8, 2014. They found that of the 6,655 hospitalizations examined, 61.2 percent occurred in people between the ages of 18 and 64.
"Last season, when influenza A (H3N2) viruses were the predominant circulating viruses, people 18 to 64 years accounted for only 35 percent of hospitalizations," noted CDC.
In 2009 to 2010, another year when H1N1 was the main circulating virus, adults below age 65 accounted for around 56 percent of hospitalizations.
When looking at estimated rates of influenza hospitalization for the whole season, the researchers found that people aged 65 or older had the highest rate (50.9 per 100,000), followed by people between the ages of 50 and 64 (38.7 per 100,000).
Dr. Arriola and team also examined instances of flu-associated deaths. Of the 571 they identified between September 29, 2013 and February 8, 2014, 62 percent occurred in people between the ages of 25 to 64.
The other report, led by Brendan Flannery, PhD, of CDC's National Center for Immunization and Respiratory Diseases, looked at the effectiveness of the flu vaccine to prevent illness so far this season.
To explore this, Dr. Flannery and team looked at 2,319 children and adults who participated in the US Influenza Vaccine Effectiveness Network between December 2, 2013 and January 23, 2014.
The researchers estimated that during this time, overall vaccine effectiveness for people of all ages and all types of flu was 61 percent.
Dr. Flannery and team noted that the flu is still circulating and recommended that anyone who is aged 6 months or older who has not been vaccinated should receive a vaccine.
In a CDC news release, Tom Frieden, MD, MPH, Director of CDC, said that the nature of this season's flu could serve as a wake-up call.
“Flu hospitalizations and deaths in people younger- and middle-aged adults is a sad and difficult reminder that flu can be serious for anyone, not just the very young and old; and that everyone should be vaccinated,” said Dr. Frieden. “The good news is that this season's vaccine is doing its job, protecting people across all age groups."
Both reports were published in CDC's Morbidity and Mortality Weekly Report. No conflicts of interest were reported for either report.