Signs from Australia suggest a tough version of the influenza virus could hit the Northern Hemisphere this winter
By Sumathi Reddy – The Wall Street Journal – Oct. 2, 2017
It’s been an ugly flu season in Australia.
That’s why some experts are bracing for more of the same in the U.S., which has already started seeing scattered outbreaks at college campuses and nursing homes.
The Southern Hemisphere’s experience with the influenza virus during its winter, from June to the end of August, tends to be a good predictor of how hard it hits the Northern Hemisphere later the same year, says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, part of the federal National Institutes of Health.
But there are several things notably different between the U.S. and Australia. In Australia it’s only recommended that high-risk groups like children and the elderly get the annual flu shot. In the U.S., the Centers for Disease Control and Prevention recommends that everyone over 6 months old gets vaccinated.
How widely influenza spreads also depends on the background immunity of the population, Dr. Fauci says. If we’ve been exposed to a similar strain of the virus in the previous season, it might lessen the burden this year.
Dr. Fauci says it appears that this year’s flu vaccine is pretty well-matched to the virus that experts expect to circulate. However, this could change.
Making the flu vaccine is an imprecise science that includes some guesswork. Scientists must predict months ahead of time which strains will circulate the following flu season. It’s a moving target: The flu virus can and does mutate or change quickly.
There are three main types of the flu virus—A, B and C—though humans are infected mainly by the A and B viruses. The A viruses are more serious, and include H1N1 and H3N2.
The CDC recommends getting the influenza vaccine by October’s end. It usually takes about two weeks to be protected from the vaccine, and flu season typically starts in November and peaks in February, says Dan Jernigan, head of the CDC’s influenza division. Dr. Jernigan says the vaccine can last up to a year in younger, healthy adults, though it is more likely to wear off more quickly for the elderly.
He says Australia was hit with the H3N2 virus during their winter, similar to what happened in the U.S. last winter. “It’s possible that they may be seeing what we saw last year since, the viruses are relatively the same,” he says. H3N2 typically causes more deaths and hospitalizations than H1N1 and causes more illnesses in the elderly especially, Dr. Jernigan says.
This year manufacturers are predicting that 75% of the U.S. vaccine supply will be “quadrivalent,” meaning the shot will provide protection against two influenza A viruses and two influenza B viruses. The trivalent shot protects against the A viruses and one B virus.
Influenza B usually shows up later in the flu season, about a month after influenza A. It’s not as severe for most age groups.
For those who are needle-shy, there is also a version of the vaccine that uses a microneedle that is 90% smaller than the standard needle used for vaccinations.
For those 65 and up, experts recommend two stronger vaccines. One is Fluad, a vaccine made using an adjuvant, which helps create a stronger immune response in the body and first became available last year. The other is Fluzone High-Dose, a vaccine that contains four times the amount of antigen as the regular vaccine and was approved for use in 2009.
Both options may result in more pronounced side effects, such as muscle aches, headaches and redness or swelling at the site of injection.
Two other vaccines are made using newer technologies that do not require growth of viruses in chicken eggs, the procedure for most flu vaccines: Flucelvax, from Seqirus, and Flublok, from Protein Sciences. They may be able to maintain a better match to circulating H3N2 influenza viruses.
Dr. Jernigan says flu vaccines have improved in recent years. Still, their effectiveness widely varies depending on the year. At best, they prevent the flu in 60% of recipients.
That helps explain disappointing coverage rates. Last year only 46.8% of the eligible U.S. population received a flu shot, according to new CDC data, up just 1.2 percentage points from the previous year.
There are ways to improve your body’s response to the influenza vaccine. Studies have found that behavioral and psychological factors such as exercise, sleep and moods are associated with how well the body can produce antibodies when getting a vaccination.
“We’re very clear that psychological and behavioral factors are associated with how well vaccinations work,” says Kavita Vedhara, a professor of health psychology at the University of Nottingham, in England.
Dr. Vedhara was senior author on a study of 138 adults between 65 and 85 that was published in September in the journal Brain, Behavior, and Immunity. It found that people who reported a positive mood based on a validated questionnaire on the day they received the influenza vaccine had an enhanced response to the vaccine, producing more antibodies.
Write to Sumathi Reddy at [email protected]