US Flu Rates Still Under Epidemic Threshold, CDC Says

While clinical laboratories have reported high flu activity, the overall numbers have decreased for the fourth week in a row, according to the US Centers for Disease Control and Prevention as of March 13^th.

However, they noted that due to the novel coronavirus outbreak, health care-seeking behaviors may differ and their data may have been impacted.

The most commonly reported flu virus this season is the influenza A(H1N1)pdm09, the CDC’s update said. The agency also reported an increase of the cumulative hospitalization rate for the season, to 61.6 per 100,000. They additionally reported 8 new pediatric deaths associated with the flu, bringing this season’s total to 144 so far. The percentage of deaths attributed to pneumonia and the flu is 7.1% which is notable because it is below the epidemic threshold of 7.3%.

From the start of flu season (October 2019) through March 7^th, the CDC reports there have been between 36 and 51 million flu illnesses, between 17 and 24 million flu medical visits, 370-670,000 flu hospitalizations and 22,000-55,000 flu deaths.

A Washington Post investigation found that the Life Care Center nursing home in Kirkland, Washington believed they were dealing with a flu going around their facility in February. Eventually, they determined that their facility was the first deadly cluster of the novel coronavirus.

“Records, interviews and a close examination of information released by the nursing home and authorities point to a series of missed opportunities to limit exposure to the spreading coronavirus at the Kirkland home,” the Post wrote.

So, what’s the difference between the flu and coronavirus?

Experts say that those with coronavirus typically develop symptoms similar to the flu but may also develop gastrointestinal symptoms. While flu symptoms can resolve in about a week, the coronavirus seems to have more severe symptoms such as dry cough, shortness of breath, a sore throat, fever and aches, according to a comparison of the viruses from The New York Times.

In other influenza news:

• The FDA approved the first adjuvanted quadrivalent flu vaccine called Fluad, according to a Seqirus company press release. The drug is for adults 65 years and older and is designed to “help strengthen, broaden and lengthen the body's immune response against the influenza strains contained in the vaccine.”
• Current vaccines that prioritize elderly patients may be less effective than previously thought at reducing morbidity and mortality, suggesting that additional and supplementary therapies may be required, according to a paper published in Annals of Internal Medicine. The paper focused on adults aged 55 to 75 years residing in parts of the U.K. between 2000 and 2014.
• A paper in Clinical Infectious Diseases by CDC investigators found that vaccine effectiveness was low to moderate for flu prevention among adults aged older than 65 years during 2 flu seasons, but highdose vaccines provided more protection. They studied 1107 vaccinated patients, of which 622 got the high-dose vaccine and 486 received the standard dose. Overall, 1 in 5 patients tested positive for influenza, including 16% of high-dose vaccine patients, 18% of standard-dose patients, and 24% of an unvaccinated group.
• Investigators from the Universitat de Barcelona conducted a trifecta of studies focused on the aspects of the detection of influenza as well as the features of the flu detected in patients under 18 years of age. In the first study, the investigators determined that the ability of different symptoms to predict confirmed flu depended on age groups. Using the WHO definition of flu, they found that high temperature got the highest predictive value in patients over 65 while cough got the highest value in patients between 5 and 14 years of age. The research was published in the journal Viruses.
• The team also studied the 2010 through 2017 influenza seasons to compare laboratoryconfirmed-influenza cases from primary care vs. the hospital using surveillance data from health care providers. The primary care doctors were shown to predict a case 1.6 weeks before the rest of the sources, they found. They still maintain that the surveillance system should include hospitalization data despite not presenting a severe influenza. Their second study was published in BMC Public Health.
• In their third study, the team examined data for children under the age of 2 from the 2010 through 2016 flu seasons. Of 291 registered cases, 79.4% of them were caused by influenza A and the remainder were caused by influenza B. Children under 2 had more than half of the cases at 56%, and the most common complication was pneumonia. One in 5 cases required hospitalization in the ICU, the study authors added. This study was published in Scientific Reports.

Much of the influenza-associated burden occurs among infants and low- and lower-middle-income countries, according to a paper published in The Lancet Global Health. The investigators, funded by the WHO and the Bill & Melinda Gates Foundation, estimated the regional and global burden of flu-linked respiratory infections in children under 5 based on previously published studies. Based on what they found, there were about 109.5 million flu virus episodes among children under 5 worldwide. The flu accounted for 7% of acute lower respiratory infection (ALRI) cases, 5% of ALRI hospital admissions, and 4% of ALRI deaths, they said.