Influenza: Lessons from Last Season, Looking Ahead to the Next

DECEMBER 05, 2018
Cecilia Pessoa Gingerich
hepatitis C in 2018

Every year shortening days and colder weather come with the warnings and advice about protecting oneself and others from the flu. It’s National Influenza Vaccination Week, when public health officials hope to prompt the reluctant or forgetful among us with a reminder that it’s not too late to get that #flushot.
 

Lessons from the 2017-2018 Flu Season

Last season was hyped in the press and at dinner tables as a particularly intense flu season. While it was “relatively bad” according to Anthony Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health (NIH), it was not exceptionally so.

“The 2014-15 season was just as bad, if not worse,” Fauci told MD Magazine® in January. “Though the perception has been ‘Wow, this is unprecedented,’ in no way is it unprecedented.”

Nonetheless, the Centers for Disease Control and Prevention (CDC) estimated that over the 2017-2018 influenza season, 48.8 million people were sick with influenza. This was higher than any season since the H1N1 pandemic of 2009, when and estimated 60 million were infected with the flu. Additionally, hospitalizations due to the flu reached 959,000 and there were 79,400 deaths related to influenza last season, with an estimated 600 deaths in children.

To combat myths and encourage vaccinations, many health care professionals have spoken out publicly reminding everyone of the importance of the annual flu shot.
 
While the general advice—get vaccinated—remains the same for this year, there have been advances in research and treatments over the past year.

Recent Advances in Influenza Research and Treatment

Research published over the past year has shown that the annual vaccination doesn’t reduce efficacy in children, and that the influenza vaccine is safe for people who also take statins. On the treatment side, baloxavir marboxil has been approved by the FDA to join other antiviral treatments for people who do become infected.

Investigators using data from medical records over a period of 3 flu seasons showed that the effectiveness of a flu vaccine was actually higher in children vaccinated in both the enrollment season and prior season, compared to children vaccinated only in the study’s enrollment season.

“The severity of each flu season is unpredictable, and children die each year from the flu. Even healthy kids can become severely ill and die from flu,” Huong Q. McLean, PhD, MPH, told MD Mag. “Getting the flu vaccine every year is the best way to protect your child against the flu. The vaccine is safe, my family, including my 2 kids, get the vaccine every year.”

Another study, described as “reassuring,” found that statin use did not affect flu vaccine effectiveness. Of the 11,692 participants, 30% (n = 3359) were statin users and 65% (n = 7584) had been vaccinated against influenza. The vaccine effectiveness rate was 38% when adjusted for potential confounders, and when statin use was factored in, the rate remained at 38%.

Even those do choose to get a vaccination may still become infected, though studies show that flu severity is lessened for those who are vaccinated. Several antiviral treatments are available for influenza, including oseltamivir (available in generic versions and as Tamiflu), zanamivir (Relenza), and peramivir (Rapivab).

The new option this season is the single-dose antiviral drug, baloxavir marboxil (Xofluza), which was approved by the US Food and Drug Administration (FDA) on October 26, 2018 for the treatment of acute uncomplicated flu in adults and children 12 years of age and older who have had flu symptoms for less than 48 hours.

The approval of baloxavir marboxil, which received priority review designation from the FDA in June, was supported by the results of the phase 3 CAPSTONE study trials, in which single-dose baloxavir marboxil was compared with twice-daily placebo or oseltamivir 75 mg over 5 days. Investigators found that patients treated with baloxavir marboxil had improved flu symptoms in a median time of 73.2 hours versus 102.3 hours in patients treated with placebo (P < .0001).

“Flu season is already well underway, and the US Centers for Disease Control and Prevention recommends getting vaccinated by the end of October, as seasonal flu vaccine is one of the most effective and safest ways to protect yourself, your family and your community from the flu and serious flu-related complications, which can result in hospitalizations,” Scott Gottlieb, MD, FDA Commissioner, said in a statement about the baloxavir marboxil approval.

Looking Ahead to This Flu Season

The 2018-2019 influenza season is upon us, but while there’s no way to predict when this season will peak, over the years, data has shown that the influenza season in the United States picks up in October and peaks from December to February, sometimes lasting as late as May. Since 1982, February has been the peak month more than twice as many times as other months. Even though the CDC recommends getting the flu vaccine as early as possible—by the end of October preferably—they state that getting the vaccine in December, January, or even later can still be beneficial.

While public health officials and doctors across the country recommend that everyone who is able to get vaccinated, it’s not a one-size-fits-all scenario. There are many options available that may fit the needs of different populations.

“It’s not just as simple as ‘everybody needs to be vaccinated for the flu’ and I think it’s a positive thing,” Troy Trygstad, PharmD, MBA, PhD, told MD Magazine® in an interview about the 2018-2019 influenza season.

The CDC lists many flu vaccine options available this year including the standard dose trivalent vaccine from virus grown in eggs, standard dose quadrivalent vaccine from virus grown in eggs, quadrivalent vaccine containing virus grown in cell culture, and the recombinant quadrivalent vaccine that is a completely egg-free option. There are also high-dose trivalent vaccines and trivalent vaccines with adjuvant for adults 65 years of age and older.
                   
Many of the vaccines can be given either with a typical hypodermic needle or, for patients 18 to 64 years of age, via a jet injector. The live attenuated influenza vaccine (LAIV), which is administered via a nasal spray.

However, the bottom line advice is that everyone over the age of 6 months should get vaccinated against the flu. Not only does it benefit the person who is vaccinated, it protects others, especially the elderly and children who are more susceptible.

Data collection on the current season is ongoing, with new numbers released weekly. As of November 24, the CDC reported sporadic or local flu activity in most US states. The influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses are circulating, with influenza A(H1N1)pdm09 the strain most commonly reported since September 30, 2018.

Additionally, the surveillance of influenza-like illness found that the proportion of outpatient visits for these symptoms increased to 2.3%, exceeding the national baseline of 2.2%.

While the flu season has already begun, National Influenza Vaccination Week is in December as a reminder that it’s still not too late to get that flu shot. To anyone looking for a location, the CDC and partners have a Vaccine Finder to help people find a place to get vaccinated.

This article is part of MD Magazine's This Year In Medicine 2018 series. To read more from the series, check out the links below and follow us on Twitter at @MDMagazine.

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