CDC Offers Update on Flu Activity This Season

The CDC on Friday offered its weekly snapshot of influenza activity so far this season. Among the findings for the week ending January 12:
Influenza A(H1N1)pdm09 viruses have predominated in most regions, although influenza A(H3) viruses have been most common in the Southeast.
Most circulating viruses are genetically similar to the reference viruses used for this year's flu vaccines.

All tested viruses have been susceptible to neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir). Information on susceptibility to the newly approved flu drug, baloxavir, will be available later in the season.

New York City and 22 states had either high or moderate influenza activity.

The CDC also estimated that between 6.2 and 7.3 million people in the U.S. had symptomatic influenza from October 1, 2018, through January 5, 2019. This led to some 2.9 to 3.5 million medical visits and 69,300 to 83,500 hospitalizations. The agency noted that this is the first time it's reported in-season estimates, so the numbers can't be used to evaluate how this season compares with prior seasons.

My Take:
There was no data on the estimated number of related deaths given by the CDC. All the vaccines noted are administered through a shot. There was no data on the nasal vaccine.

Study Offers Clues for Improving Seasonal Flu Vaccine

The 2017-2018 flu season was rougher than most. During peak flu activity in February, more than 10% of deaths in the U.S. were attributed to the flu or pneumonia, according to the Centers for Disease Control and Prevention.

To help combat the flu, NIH-supported researchers are exploring how to improve vaccines. Current influenza vaccines mainly target the influenza surface protein hemagglutinin (HA) but can sometimes offer varying or limited protection.

Recent studies indicate that seasonal flu vaccines might provide better protection if they were optimized to include an additional target, a different flu surface protein called neuraminidase (NA).

The study is supported by the National Institute of Allergy and Infectious Diseases. This study and related efforts are part of NIH’s larger plan to develop a universal vaccine – one that can durably protect all age groups against multiple strains of the flu.
Remember to get your seasonal flu shot every year to help protect yourself and your loved ones.

My Take:
There are several problems with our current vaccination process. The concepts are over 100 years old and the technology is quite dated as well.

What Makes This Flu Season So Bad?

Out of every 100,000 hospitalizations in the U.S., 22.7 were for the flu in the first week in January. According to the CDC, the number had doubled from the week before. During the severe flu season that ended in 2015, rates of hospitalizations reached 29.9 for every 100,000.

The winter season that began in 2017 and will end in 2018 “unquestionably falls into a bad year,” says Anthony Fauci, director of the National Institutes of Health National Institute of Allergy and Infectious Disease. First is the nature of the most dominant flu strain infecting people – H3N2. Flu viruses mutate every year, and it’s common to see several strains of flu during the same season. A similar strain called H1N1 was responsible for the 1918 flu pandemic, and the 2009 “swine flu” outbreak. “H3N2 is historically the bad actor among influenzas,” he says. “It’s also associated with complications.”

The second reason H3N2 has been so pervasive, says Fauci, is people have less exposure to it. When the same flu strain strikes repeatedly, people and thus regions tend to build up immunity.

The third reason this year’s flu has been so bad is complications with the vaccine. Most influenza vaccines are grown in chicken eggs, and when this year’s vaccine was being incubated, the virus mutated while it was growing and became less effective. Scientists think it may only be about 30% effective against H3N2. In Australia, the vaccine was only 10% effective.

At best, says Fauci, flu vaccines are only ever about 60% effective. While that makes it a least 60% more effective than not getting a vaccine at all, it still means the rapidly mutating virus has a fighting chance. Every year, the World Health Organization (WHO) meets to determine what specific flu strains should receive vaccines in the northern hemisphere. H3N2 was one of several identified as a threat.

There are four different types of influenza virus, three of which infect people. Of those three, influenza A and B are the most common and each of those subsets develops different strains. H1N1 and H3N2, for example, are strains of influenza A, and they adapt by constantly changing their surface proteins.

Only 23 Percent Protection from This Year’s Flu Vaccine

A new study finds the current vaccine reduces your risk of needing medical care because of flu by only 23%.

Most years, flu vaccine effectiveness ranges from 10 to 60% reported the U.S. Centers for Disease Control and Prevention (CDC).

Despite the reduced effectiveness of this season’s flu shot, “vaccination is still important,” said lead report author Brendan Flannery, an epidemiologist with the CDC. “But there are ways of treating and preventing flu that are especially important this season,” he added.

These include early treatment with antiviral drugs and preventing the spread of flu by washing hand and covering coughs, he said.

Twenty-three percent effectiveness means that there is some benefit – a little less flu in the vaccinated group. Flu is usually more common among unvaccinated Americans, Flannery said, “but this year there is a lot of influenza both in people who are vaccinated and in people who are unvaccinated.”

The findings are published in the January 16th issue of the Morbidity and Mortality Weekly Report.
In flu seasons when the vaccine is well matched to the circulating H3N2 strains, effectiveness has been between 50-60%, the CDC said. This year, however, about 70% of the H3N2 virus seen has been different from the H3N2 strains in the vaccine, which explains its reduced effectiveness, Flannery said.

This year’s shot is most effective – 26% - for children 6 months old through 17 years. Older people get less benefit – just 12% of those 18 to 49 years and 14% for those 50 and older, the CDC said.