News from the FDA/CDC

Drop in flu activity may not signal seasonal peak


A key indicator of flu activity dropped but remains high, but measures of severity have not yet shown any unusual increases, according to the Centers for Disease Control and Prevention.

Influenza-like illness activity level, week ending Jan. 4, 2020

Patients with influenza-like illness (ILI) made up an estimated 5.8% of the visits to outpatient providers during the week ending Jan. 4, and that’s a decline from 7.0% for the last full week of 2019, the CDC’s influenza division reported.

That 7.0% outpatient ILI visit rate was the highest seen in December since 2003, but “hospitalization rates and percent of deaths due to pneumonia and influenza remain low,” the influenza division said in its weekly report.

Influenza B/Victoria and influenza A(H1N1)pdm09 viruses have been the predominant strains so far this season, and they “are more likely to affect children and younger adults than the elderly. Because the majority of hospitalizations and deaths occur among people age 65 and older, with fewer illnesses among that group, we expect, on a population level, to see less impact in flu-related hospitalizations and deaths,” the CDC said.

Last year, there was a similar drop in the outpatient ILI rate in early January after visits rose through December. The rate then increased for another 5 weeks before peaking at 5.0% in February. A similar pattern also occurred during the 2016-2017 and 2015-2016 seasons, CDC data show.

The nationwide ILI hospitalization rate, which is cumulative through the season, was up to 14.6 per 100,000 population for the week ending Jan. 4, the CDC said. Here are the corresponding rates for each of the last five seasons:

  • 11.6 (2018-2019).
  • 30.5 (2017-2018).
  • 12.2 (2016-2017).
  • 1.8 (2015-2016).
  • 38.3 (2014-2015).

There were five new ILI-related pediatric deaths reported for the week ending Jan. 4, two of which occurred the week before. The total is now up to 32 for the 2019-2020 season, the CDC said in the weekly report. Last season, there were 21 pediatric deaths through the first January report, compared with 42 during the 2017-2018 season and 13 in 2016-2017.

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