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Why You Really Need A Flu Shot (Even Though The Vaccine Isn’t Great)

(WFIU Public Radio/Flickr)

(WFIU Public Radio/Flickr)

By Richard Knox

This flu season is shaping up to be a bad one. And this year’s vaccine doesn’t work very well against the most common flu virus going around. So should you even bother getting a flu shot?

Yes. Putting it a different way: My wife, my daughters and I will. And the evidence says you’d be somewhere between slightly foolish and dangerously blasé if you don’t — depending on your personal risk factors.

I know there are naysayers — the Internet is full of them. “I recommend that my patients of all ages not take these incessantly promoted immunizations, primarily because of their lack of effectiveness,” writes blogger Dr. John McDougall. He says he’s not one of those across-the-board vaccine deniers but just doesn’t think flu vaccines (of any given year) are worth taking.

To understand why I think he’s wrong — even this year, when vaccine effectiveness is expected to be even lower than usual — you need to know something about the situation we’re all in.

Several viruses circulate during any given flu season. And flu viruses are always changing — sometimes not so much from year to year; sometimes in a bunch of little ways (a phenomenon called genetic “drift”); and sometimes in a big, sudden way, called a “shift,” which touches off pandemics.

Drifts Or Shifts?

Public health researchers constantly monitor flu virus mutations. But even the smartest flu dudes can’t know in advance when they’ll happen, or whether mutations will be drifts or shifts.

This year, one of the flu viruses outwitted them. Or, since viruses can’t have intentions, it’s better to say that random genetic drift in that viral strain, called H3N2, happened in late March. That’s a bad time in the annual cycle of vaccine production.

Just a few weeks earlier, leading flu specialists gathered at the World Health Organization in Geneva and decided that this season’s vaccine (for the Northern Hemisphere) should contain the same viruses as last year’s — two type-A viruses (an H1N1 that caused the pandemic of 2009 and has stuck around since, and an H3N2 that first appeared in Texas two years ago) and two type-B flu viruses.

Late-Breaking Mutant

Making each year’s flu vaccine is a complicated business that waits on no virus. The recipe has to be decided in February to get the chosen viruses growing in hundreds of millions of special chicken eggs, the first step in vaccine production. Continue reading

Reality Check: How People Catch Ebola, And How They Don’t

Dr. Elke Muhlberger (Courtesy of Kalman Zabarsky for BU Photography)

Dr. Elke Muhlberger (Courtesy of Kalman Zabarsky for BU Photography)

It’s confusing. You hear that Ebola victim Thomas Eric Duncan was so contagious that two Dallas nurses in protective gear caught the virus. But then you hear, in more recent days, that apparently nobody else did, including the inner circle who lived with him and cared for him. The CDC announced today that all of Mr. Duncan’s “community contacts” have completed their 21-day monitoring period without developing Ebola.

How to understand that? And how to address alarmists’ claims that for the nurses and so many West Africans to have caught Ebola, it must have gone “airborne”?

I turned to Dr. Elke Muhlberger, an Ebola expert long intimate with the virus — through more than 20 years of Ebola research that included two pregnancies. (I must say I find this the ultimate antidote for the fear generated by the nurses’ infections: A researcher so confident in the power of taking the right precautions that she had no fear — and rightly so, it turned out — for her babies-to-be.)

Dr. Muhlberger is an associate professor of micriobiology at Boston University and director of the Biomolecule Production Core at the National Emerging Infectious Diseases Laboratories (widely referred to as the NEIDL, pronounced “needle”) at Boston University. Our conversation, lightly edited:

Is it really true you worked on Ebola through two pregnancies?

Yes, but in the proper protective gear. That makes a huge difference, if you’re protected, if you know how to protect yourself, and that is the case in a Biosafety Level 4 lab, of course. If you compare the protective gear we’re wearing in a Biosafety Level 4 lab and the gear they’re wearing in West Africa now treating patients, it’s like comparing a stainless steel vault to a cardboard box.

But on the other hand, if you look at the nurses in Dallas, you say, ‘How did they get infected?’ It makes you worry that maybe protective gear isn’t good enough — but you’re proof of the opposite.

A Biosafety Level 4 lab is such a high-end lab, it is not possible to use protective gear like that in every hospital in the U.S.

Could you please lay out a brief primer on the biology of how Ebola is transmitted?

We know from previous outbreaks, and also from the current outbreak, that Ebola is transmitted by having very close contact to infected patients. So we know that it is transmitted by bodily fluids, which include blood, first of all — because the amount of virus in the blood is very, very high, especially at late stages of infection — but it’s also spread by vomit, by sputum, by feces, by urine and by other bodily fluids.

The reason for that is that at late stages of infection, the Ebola virus affects almost all our organs — it causes a systemic infection. One main organ targeted by Ebola virus is the liver, and that could be one of the reasons that we see these very high concentrations of viral particles in the blood. But I would like to emphasize that that occurs late in infection.

Early infection is the other way around. The primary targets — the first cells that come in contact with Ebola virus and get infected — are cells that are part of our immune system. And these cells most likely spread the virus throughout our body. But there are not so many cells infected at the very beginning of the infection, which might be the reason why Ebola virus patients do not spread virus at the very beginning of infection. And that’s why it’s safe to have contact with these patients, because the viral titers in their blood are so low that we cannot even detect them with methods like PCR, which is one of the methods we use to diagnose Ebola virus.

Is a virus only contagious when it reaches a certain level of “titer” or load? Continue reading