Two more influenza-associated pediatric deaths have been reported to the Centers for Disease Control and Prevention, bringing to 13 the number of such deaths for the current flu season.
New York City and 19 states, including Massachusetts, are experiencing high influenza-like illness activity in terms of visits to outpatient providers for symptoms such as a fever of 100 degrees, cough and sore throat, and the flu is considered widespread geographically in the commonwealth as well as in 23 other states.
Some 3.4 percent of visits to reporting outpatient providers in Massachusetts were for influenza-like illnesses for the week ending Dec. 29, according to the state’s most recent flu activity report.
All the state’s regions were reporting the proportion of these visits above baseline with the highest rates in the Northeast and Southeast regions at 5.15 and 4.61 percent, respectively, and the lowest in the West at 1.57 percent.
The Northeast also had the highest number of laboratory-confirmed cases for the week at 275 as well as the highest number to date this season at 718.
The number of laboratory-confirmed cases to date in the state is 2,194. Last year at this time, there were 1,298 laboratory-confirmed cases of flu.
The cumulative rate of influenza-associated hospitalizations in the state between Sept. 30 and Dec. 29 is 2.86 percent and is similar to the rate during last year’s severe season at this time.
According to the CDC, the proportion of outpatient visits for influenza-like illness in the country increased to 4.1 percent for the week ending Dec. 29, which is above the national baseline of 2.2 percent.
All 10 surveillance regions of the country, according to the CDC, reported influenza-like illness activity at or above their region-specific baseline level with the percentage of outpatient visits ranging from 1.7 to 6.1 percent during week 52.
The CDC said the increase in the percentage of such patient visits may be “influenced in part by a reduction in routine healthcare visits during the winter holidays, as has occurred during previous seasons.”
A cumulative rate of 5.4 laboratory-confirmed influenza-associated hospitalizations per 100,000 population is reported by the CDC for the period between Oct. 1 and Dec. 29.
A total of 1,562 laboratory-confirmed influenza-associated hospitalizations were reported during this period with the highest hospitalization rate at 14.5 hospitalizations per 100,000 among children younger than 5 years.
The CDC said both of the newly-reported pediatric deaths were associated with influenza A(H1N1)pdm09 viruses and occurred during weeks 51 and 52, that is, the weeks ending Dec. 22 and 29, respectively.
It warned Dec. 21 that the H1N1 viruses have predominated to date and are associated with “significant illness and severe illness among young children” as well as higher rates of hospitalization.
The H1N1 virus that emerged in 2009 caused a global outbreak and that pandemic caused severe illness in some children as well as young-and middle-aged adults.
Since influenza-associated pediatric mortality became a nationally-notifiable condition during the 2004-2005 season, the total number of influenza-associated pediatric deaths has ranged from 37 to 185 last year.
These figures exclude the 2009 pandemic, when 358 pediatric deaths were reported to CDC during April 15, 2009, through Oct. 2, 2010.
Flu season often peaks between December and February with increasing flu-related deaths, hospitalizations and visits to outpatient providers.
Influenza is highly contagious, though most people recover within two weeks. There is no cure, though annual vaccination recommended for those six months and older anytime during the season provides immunity depending on circulating viruses, lessens the severity if someone is infected and helps prevent the spread of the disease that can be fatal for the young and elderly and those with underlying medical conditions.
Traditional flu vaccines – trivalent vaccines – are made to protect against three flu viruses; an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus. There are also flu vaccines made to protect against four flu viruses called quadrivalent vaccines.
According to the CDC’s most recent flu surveillance report for the week ending Dec. 29:
- Among 157 hospitalized adults with information on underlying medical conditions, 144 – or 91.7 percent – had at least one reported underlying medical condition, the most commonly reported were obesity, metabolic disorder and cardiovascular disease.
- Among 57 hospitalized children with information on underlying medical conditions, 23 or 40.4 percent – had at least one underlying medical condition; the most commonly reported were asthma and obesity.
- Among 24 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 6 – or 25.0 percent – were pregnant.
- CDC has antigenically or genetically characterized 395 influenza viruses collected Sept. 30 through Dec. 19 and submitted by U.S. laboratories, including 242 influenza A(H1N1)pdm09 viruses, 108 influenza A(H3N2) viruses, and 45 influenza B viruses.