What You Need To Know About The Flu

Tufts' Dr. David Snydman gives us the scoop on this year's flu season and why vaccines are still so tricky.

The Flu

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This is the first post in a series in which we’ll hold Q+As with some of our Top Doctors, exploring medicine through topics from around the region.

You know the feeling. The one where you’ve been hit by a truck, or you’re kind of wishing you could be. It’s the flu: one of the most notorious of our everyday viruses, and also one of the most dangerous. According to the CDC, five to 20 percent of the US comes down with the flu every year, and the number of resulting deaths can range from 3,000 to nearly 50,000. This year’s flu season was very light, but it’s not over yet, and as is the nature of the flu, an outbreak could happen anytime. To help keep you prepared, we’ve picked the brain of one of this year’s Top Docs, Dr. David Snydman, Chief of Geographic Medicine and Infectious Diseases at Tufts Medical Center.

So far this year, what have you seen of the flu season?
It’s actually been quite mild, and that’s true both nationally as well as locally. In terms of overall activity for influenza in the United States, it’s been mostly sporadic cases and compared to other years, I would say it’s been much, much less.

Just for example, there have only been close to 4,000 specimens that have gone to the Centers for Disease Control nationally, across all 50 states. Last year, it would have been five times as many. And probably 20 percent of those 4,000 are positive.

What accounts for all the variation we see from flu season to flu season?
It’s probably mostly related to the virus itself and the changes in the proteins that are expressed on the virus. There can be … slight changes or large changes that occur because the virus has the capacity to change its outer membrane proteins to some extent, which [is the part that] humans recognize and develop antibodies to.

I think the other thing that’s happened is that, especially for the last two years, there has been a better uptake of the vaccine and the vaccine has been more closely matched to the strains that are circulating. Therefore, I think there is a greater degree of immunity in the population, which may be another reason why there is less virus circulating.

What does the flu vaccine actually do? How does it work and how long does it need to be effective?
Unfortunately it only lasts for a year, and of course the strains may change a little bit from year to year. So the vaccine, when injected, provides certain antigens [i.e., something that causes an immune response]. When the vaccine is injected … those antigens are presented to the body and the body develops an immune response, and that’s what provides the level of protection. We think it takes three to four weeks to be effective, typically.

Why, in your opinion, do so many people still make the decision not to get the flu shot?
There’s a certain degree of mythology out there. For example, there is the myth that you can get the flu from the vaccine, but it’s a killed vaccine. There’s no way that you can get the flu from the vaccine. And I think people are also afraid of getting shots, and sometimes, even if they’ve gotten the vaccine, they might be incubating some other kind of infection — you know, a cold virus or something — and so they may ascribe it, from a timing standpoint, to the vaccine.

It always seems like a universal flu vaccine is on the horizon, but it’s still not here. Why is this taking so long?
The development of flu vaccines has been very complicated because of the ability of the virus to mutate. These two [key proteins on the outside of the virus] can mutate fairly unexpectedly, and in doing so [the virus] could present itself as totally new to humans and spread like wildfire — which is what happened with the swine flu a couple of years ago. The H1N1 [outbreak strain of 2009] really appeared in April or March in Mexico about two years ago, and then we had an epidemic in the summer.

At this point there’s no artificial vaccine system that can express all of these different protein combinations that could theoretically give more universal protection. So that’s the problem, and we are definitely not there yet.

Washing your hands seems so basic — why is it so effective a preventive measure that it remains one of the most recommended habits. Is there anything else that we should do?
Certainly hand hygiene is very important. If you are feeling a little ill, in terms of reducing the spread, you should cover your cough and avoid crowds. Also, be alert: the symptoms of the flu are pretty straightforward, although they can vary. People will start having fever, significant muscle aches — they may feel like they’ve been run over by a truck.

If you have a fever, you should stay hydrated. If you have a viral illness, you should take Tylenol, not aspirin, because you can get side effects taking aspirin with certain viral infections, and the flu is one of them. You should certainly get vaccinated, and if you’re feeling ill, there are some antiviral medications that might be useful, depending on the strain circulating. This year, the strain circulating has been susceptible [to antiviral treatments], but there is the possibility of these viruses becoming resistant, so we don’t want to overuse these kinds of medications. We’d like to use them in appropriate patients, but your physician will know whether to prescribe them or not.