CDC: Flu season could peak early this year

There is a 40 percent chance flu season could peak this month, according to the Centers for Disease Control and Prevention’s FluSight Forecasting initiative.

The CDC’s flu surveillance report for the week ending Nov. 30 shows the percentage of visits to outpatient providers for influenza-like illnesses has been at or above the national baseline for four weeks.

Twelve states are seeing what is considered high amounts of such visits, and this activity is expected to increase over the next few weeks.

Flu is geographically widespread in 16 states, including Massachusetts, though at different levels of intensity, and B viruses, generally seen later in the season, are said to predominate across the country.

A total of six influenza-associated pediatric deaths have been reported to the CDC so far this season.

It is too early to predict whether the season will be a severe one, but the CDC forecast analysis shows flu activity will likely peak between December and February with a 40 percent chance of a peak in December, 30 percent for January and 25 percent in February.

Last year’s flu season extended into April and was the longest in a decade.

Early estimates from the CDC show that last year’s season resulted in 49,000 flu-related deaths, and 590,000 hospitalizations. Some 143 influenza-associated pediatric deaths have been reported to the CDC so for the 2018-2019 flu season.

All regions in the country except one – which includes Massachusetts – are at or above their baselines for the percentage of outpatient visits for influenza-like illnesses this season.

More than 10 percent of respiratory symptoms tested by clinical laboratories were said to be positive for the flu virus.

The CDC said activity is driven mostly by influenza B/Victoria viruses, generally in circulation later in the season.

Influenza A viruses are also in circulation with the dominant flu virus varying by region and age of patient, according to the CDC.

According to the Massachusetts Department of Public Health’s most recent flu report, influenza activity is currently low in the state though visits to outpatient providers are on the increase and higher than the previous two years in the same week.

According to the state DPH, Outer Metro Boston is reporting moderate influenza-like illness activity while all other regions in the state are reporting minimal to low ILI activity.

It said a comparable number of influenza A and influenza B positive specimens have been reported by hospitals and outpatient facilities in Massachusetts.

Nationally, influenza B/Victoria viruses are the most commonly reported influenza viruses among children age 0-4 years with 46 percent of reported viruses and 5-24 years with 60 percent of reported viruses, while A(H3N2) viruses are the most commonly reported influenza viruses among persons 65 years of age and older with 54 percent of reported viruses.

Among adults aged 25-64 years, approximately equal proportions of influenza A(H1N1)pdm09 and B/Victoria viruses – 35 percent and 34 percent, respectively have been reported nationally.

Flu vaccines were less effective during the last two seasons against the predominate virus. Viruses sometimes mutate from the time the components of the vaccine are created.

This year’s flu vaccines have been updated in terms of their H1N1 and H3N2 components.

Both B/Victoria and B/Yamagata virus components from the 2018-2019 flu vaccine remain the same for the 2019-2020 flu vaccine.

It is recommended anyone six months or older get annually vaccinated against the flu. Vaccination can moderate flu symptoms even in individuals who get sick from the virus, and high vaccination rates helps reduce the spread of the highly contagious respiratory disease.

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