Dr. Mark Dowell urges flu shots despite mutated H3N2 strain
By Kristy Bleizeffer Dec 8, 2014
Last week, the Centers for Disease Control and Prevention announced the 2014-2015 flu vaccine is not as protective as hoped for the seasonal influenza A H3N2 virus, a strain found to be most common so far this year. About half of the H3N2 viruses tested are “drift variants,” meaning they’ve mutated to a form not protected by the vaccine, the CDC said.
That doesn’t mean you should not get your flu shot if you haven’t already, and it doesn’t mean the vaccination you did get was a waste of time and money.
To wade through the viral soup that is the approaching flu season, the Pulse sat down with Dr. Mark Dowell, infectious disease specialist with Rocky Mountain Infectious Diseases. Here’s what you need to know.
What flu strains are included in this year’s vaccine?
The Influenza virus has many components, two of which are called the H and the N. Variations of these two components brought the H1N1 flu strain that caused so many problems in 2009-2010, and the H3N2 strain with the potential to cause headaches (and muscle aches) this year.
The Centers for Disease Control and Prevention selects three flu strains each year that are most likely to cause illness in the coming season. They look at what strains are popping up in animals and in people around the world and try to match them with the strains most likely to cause infections. This year’s predominant strains selected for the vaccine included Influenza A (H1N1) viruses, influenza A (H3N2) viruses and influenza B viruses.
“It’s an inexact science, but it’s really quite good. Most of the time, it matches around 70 percent or maybe 80 percent of flu strains for that season,” Dowell said.
“What you can’t predict are changes in the virus over a few months. What the predominant strain did this year, which is the H3N2, is it drifted a little bit. It’s called antigenic drift, which means the virus mutated over time and changed its structure just a little.”
How does this affect the vaccine’s effectiveness?
Typically, the flu vaccine is about 70 percent protective in the typical adult population. In older adults – those 65 and older – the vaccine is 40 to 50 percent protective.
“But this year, across the board, the vaccine is probably around 50 percent protective. It could not have been predicted. The virus played its own game and changed a little. This is our battle against nature every year,” Dowell said.
“We’re not as protected as we’d like to be, but it’s a lot better than nothing. It’s still going to protect those at highest risk against death and probably severe illness with hospitalization.”
Have we been seeing more flu cases because of this mutated strain?
No. We usually have a 4- to 6-week period in which the flu season peaks, and Wyoming has not yet entered that period – and neither has the rest of the country. (Click here to see why Wyoming’s flu season typically starts later than other areas.)
“We are seeing some straggling cases, which is typical for this time of year,” Dowell said. “We will have to see over time how this plays out and how much protection the population has. We do know as a baseline that on any given year, we have about 50,000 flu-related deaths in the United States. We’ll see if that goes higher this year. I doubt it will be significantly higher, but that’s a speculation.”
If antigenic drift is a thing, is it worth getting the flu shot at all?
“It absolutely is because it’s better to have some protection than none,” Dowell said.
Is it too late to get this year’s vaccine?
No. The important thing is that you get it, no matter how late. The shot lasts four to six months but is strongest after two to four weeks. So, you will likely be protected when the Natrona County season peaks in the next month or so.
“As far as I’m concerned, I’ve given them as late as February. In every flu season, there are stragglers. If we have a flu outbreak in January, there are still cases that go on into April,” Dowell said.
Can we adjust this year’s vaccine to protect against the shifted H3N2 strain?
No. It could never be changed, manufactured and distributed in time to protect people this flu season. This antigenic shift will be taken into account – along with what’s going on around the world – for creation of next year’s vaccine.
The bottom line this year is to get seen by your physician or health provider as soon as possible if you develop true flu-like symptoms, Dowell said. “The virus is going to respond to medications like Tamiflu if started 24 to 48 hours into the illness. Beyond that, the medication is probably not helpful.”
What are the symptoms of flu?
“Sicker than you probably ever been, 101 fever, severe muscle aches like I almost can’t describe, feeling like you’ve been run over like a truck,” Dowell said.
“We have to understand the public uses the term flu very loosely. The flu, you don’t forget. It’s not the stomach flu with nausea and vomiting and diarrhea. That is a completely different virus. There are millions of different viruses out there. This is the influenza virus that makes you very, very sick.”
How can you prevent getting the virus in the first place?
Practice good hand washing and use antiviral hand gel.
“If you’re that sick, you should not be at work,” Dowell said. “Here at Wyoming Medical Center, we vaccinated more than 99 percent of anyone who works here – staff, volunteers, physicians. My message has always been, I do not want employees bringing in influenza, if possible, into a facility where you have the sickest people in the state of Wyoming. All of us share that responsibility and the employees here have done a phenomenal job with it.”
Also, keep sick kids at home. “Kids are the vectors. They carry the most viruses. I call my kids the cesspools because they spread it amongst each other and they are the ones who spread it to the adults.”
Dr. Dowell is an infectious disease specialist with Wyoming Medical Center and Rocky Mountain Infectious Diseases (RMID), 1450 E. A St. He is the Natrona County health officer and is board certified in infectious disease and internal medicine. RMID offers a full-breadth of outpatient infectious disease care and is looking to expand its outreach clinics. It has three full-time physicians, a half-time physician and a full-time nurse practitioner. For more information, appointments or referrals, call RMID at (307) 234-8700.