The 2017-18 influenza season was a marathon of misery, with over 224,000 confirmed laboratory cases, 180 pediatric influenza deaths, and possibly greater than 700,000 US hospitalizations.1,2,3 Statistically, 2017-18 had the highest overall activity of influenza-like illness (7.5%) since 2009, but was the first season to be classified as a “high severity” across all age groups.1,2,3
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According to the CDC, influenza-like illness (ILI) was at or above the national baseline for 19 weeks, making the 2017-2018 season one of the longest in recent years.1,2,3 Even Hawaii, a state typically isolated from high flu activity, joined the rest of the United States with reported widespread ILI activity.
The main strain circulating last year was Influenza A(H3N2), with a surge of influenza B viruses from March to May.1,2,3 Last year’s influenza vaccine was 40% effective overall, but only 25% effective against the predominant H3N2 strain. However, CDC experts note that, even with the reduced effectiveness, the vaccine prevented 84,700 hospitalizations, 2.64 million medical visits, and 5.29 million cases.4 Manufacturers reported a record 155.3 million doses of vaccine distributed, but early season vaccination was calculated at less than 40% (38.8% children; 38.5% adults).1,2,3
The types of available vaccines for the 2018-2019 flu season include the intranasally-administered live attenuated influenza vaccine (LAIV) and recombinant influenza vaccine (RIV) as quadrivalent vaccines, and inactivated influenza vaccines (IIVs) as both a high-dose IIV trivalent and adjuvanted IIV trivalent.
According to Contagion Live,5 the trivalent vaccines include the following flu strains:
- Influenza A/Michigan/45/2015 (H1N1)pdm09-like virus
- Influenza A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus
- Influenza B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage)
The quadrivalent vaccines are the same as the trivalent, plus:
- Influenza B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage)
The CDC officially recommends all Americans age 6 months and older receive a flu vaccination preferably before October, noting that approximately 80% of pediatric flu deaths last year occurred in children who were not vaccinated.1,2,3
Injection or Nasal Spray? Experts Split This Year
The CDC Advisory Committee on Immunization Practices (ACIP) and the American Academy for Pediatrics (AAP) Committee on Infectious Diseases are the industry’s preeminent experts on influenza vaccination. Typically, both groups make the same flu vaccine recommendations to the public. But after a devastating flu season in 2017-18 in which the inactivated (flu shot) vaccine proved less than effective, the groups have made opposing recommendations this year.
For the first time since 2014, the CDC ACIP has recommended the intranasally-administered LAIV, more commonly known as FluMist.6 The CDC noted the FluMist was an acceptable option for patients age 2-49 without contraindications, as well as inactivated influenza vaccine and recombinant influenza vaccine. The FluMist green light is an about-face from last year when both the CDC and AAP recommended against using it. The CDC’s decision this year was based on data from a revised formula for FluMist, which one CDC expert says had “much better” immunization by substituting a “heartier” H1N1 vaccine strain.4
On the contrary, the AAP has recommended only the injectable inactivated influenza vaccines (IIV, trivalent or quadrivalent) as the primary choice for all patients age 6 months and older.7 IIV has consistently protected against all influenza virus strains in recent seasons, they noted. The AAP added that nasal LAIV is acceptable in rare cases when children 2 and older refuse the flu shot. AAP based its recommendation on the fact that the nasal spray vaccine’s “effectiveness against influenza A(H1N1) was inferior during past influenza seasons and is unknown for this upcoming season.”7
What does the split recommendation mean? Doctors will have the choice to offer patients the flu shot or the nasal spray, but both CDC and AAP encourage no delay in vaccination to wait for a specific vaccine. Both groups will no doubt be eager to see if one inoculation is more effective than the other against the season’s as yet to be determined dominant strain, as well. The outcome will likely influence the 2019-2020 recommendations from both advisory groups.
Obesity & Influenza
According to a study in the Journal of Infectious Diseases, obesity, which increases influenza disease severity, also extends by about 1.5 days how long influenza A virus is shed from infected adults compared to non-obese adults.8 The findings implicate chronic inflammation caused by obesity as well as increasing age as reasons for extended viral shedding, which puts others at risk of infection.
Researchers found the amount and duration of viral shedding likely affects how efficiently influenza viruses are transmitted to others. Obesity alters the immune system and leads to chronic inflammation, which also is known to increase with age.
The authors propose that chronic inflammation caused by obesity may be responsible for increased influenza A viral shedding. The researchers are continuing to study the correlation between obesity, inflammation and viruses. However, they note that reducing obesity rates could be an important target to limit the spread of viral infectious diseases.
The study also notes that obesity rates range widely throughout the world: in 2014 adult obesity in the United States was 35.5%, compared to 17.4% in Nicaragua and 4.4% in other low-income countries.8
New Antiviral in the Works
Oral administration of 150mg of the influenza endonuclease inhibitor AL-794 significantly reduced viral load, symptoms, and mucus weight in a Phase I clinical trial, according to Contagion Live.9
Researchers inoculated 61 patients intra-nasally with influenza virus (A/Perth/16/2009 H3N2) and 42 became infected. According to Contagion Live, the infected patients then received either 50 mg of AL-794, 150 mg of AL-794, or placebo twice daily for 5 days.
Results found that patients given the 150-mg AL-794 had lower viral load than those who received 50mg AL-794 or placebo.9
Researchers Closing in on Universal Flu Vaccine
A Phase 2 clinical trial sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) will test the effectiveness of an investigational universal influenza vaccine intended to protect against multiple strains of the virus.10
The trial is testing an experimental vaccine called M-001 for safety and its ability to produce potentially broad protective immune responses, both on its own and when followed by a standard, licensed seasonal influenza vaccine.
Developed and produced by BiondVax Pharmaceuticals (Israel), the M-001 vaccine candidate contains antigenic peptide sequences shared among many different influenza viruses.
Theoretically, it could protect against many current and emerging strains of influenza, the NIAID reports. Six previous clinical trials involving a total of 698 participants conducted by BiondVax in Israel and Europe indicated that the vaccine candidate was safe, well-tolerated and produced an immune response to a broad range of influenza strains.10
“The 2017-2018 influenza season in the United States was among the worst of the last decade and serves as a reminder of the urgent need for a more effective and broadly protective influenza vaccine,” said NIAID director Anthony S. Fauci, MD. “An effective universal influenza vaccine would lessen the public health burden of influenza, alleviate suffering, and save lives.” RT
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