It’s likely to be a “relatively long” flu season.
This is what the Centers for Disease Control and Prevention reports in its latest weekly flu summary that shows it received eight reports of flu-related pediatric deaths for the week ending March 16; influenza-associated activity to be widespread in 44 states and 26 states with high proportions of medical visits for flu-like symptoms compared to other medical visits for the week.
The report notes this medical visits indicator of influenza-like illness activity in the country was 4.4 percent for week 11 into the new year – the same as the previous week – and is above the national baseline of 2.2 percent.
“Influenza-like-illness levels have been at or above baseline for 17 weeks this season. By this measure, the last five seasons have averaged 16 weeks, with a range of 11 to 20 weeks,” the summary said.
“The CDC expects flu activity to remain elevated for a number of weeks, suggesting this season is likely to be relatively long.”
The CDC look-ahead initiative was more specific.
It said that “forecasts continue to indicate a greater than 90 percent chance that the flu season peaked nationally in mid-February, though there is variation in peak timing in different parts of the country this season” and that “flu activity is expected to remain elevated nationally through April.”
Influenza B viruses usually predominate later in flu season, but this year influenza A viruses H1N1 and H3N2 have predominated throughout the season. The H1N1 viruses remain predominant overall nationally and seem to be well suppressed by this year’s vaccine, but the H3N2 viruses – which can cause more severe symptoms in older adults and are known for the ability to ‘drift’ in makeup from when the vaccine was grown to match it – were more frequently reported during the week of March 16, and have been predominant during the most recent three weeks in regions 2 and 4 through 10.
The two influenza A viruses were reported in equal circulation in Region 1, which includes Massachusetts, where influenza-like illness activity remains widespread but at lower levels above its own baselines, for the week.
The eight influenza-associated pediatric deaths reported to CDC during week 11 bring the total to 76 of such reported deaths.
According to the CDC, two deaths were associated with an influenza A(H1N1)pdm09 virus and occurred during the week ending March 9; two deaths were associated with an influenza A(H3) virus and occurred during the weeks ending Jan. 26 and Feb. 23, respectively; rhree deaths were associated with an influenza A virus for which no subtyping was performed and occurred during the weeks ending March 9 and March 16, respectively; and one death was associated with influenza B virus during the week ending March 2.
Massachusetts has had three reported deaths of children this season from flu complications.