Flu Season and Shots, 9/14/12

It’s time to make flu shot plans for everybody. Influenza is a viral infection. It infects the cells lining the respiratory tract and lungs, and spreads from person to person by respiratory droplets from coughing and sneezing. Infections usually peak in February-March in North America (in the summer south of the equator) when we spend more time indoors with other people at school and work. There are several types, A and B with subtypes of each. The biologic strategy of this germ is to shift its antigenic identity a little bit each year so that people who have had it one year may be again susceptible the next year because the antibodies they made the first time are now less effective. That way the virus can find more victims and survive and spread more easily. It does not cause gastrointestinal symptoms, although often people refer to other diseases that do that as “flu” as well.

The disease takes 2-3 days to cause illness after a person is exposed. The first symptoms are usually severe sore throat and/or cough with fever and chills developing over the subsequent 24 hours. The fever lasts 2-4 days, but the patient doesn’t really feel normal for at least a week. There are some bad complications that can appear and be fatal. A very small percentage of healthy adults who get it, can develop an overwhelming viral pneumonia, white out their lungs and die quickly. Thus if someone with cough and fever over 101° gets badly short of breath, they need medical attention ASAP. The other complication, seen more often in young children and people over 60 is a secondary bacterial pneumonia. The story there is usually of a febrile illness over 2-3 days that gets better but then the fever comes back and the patient is much sicker. These patients need antibiotics to stop the bacterial infection. But for the vast majority of infected people, the treatment is just aspirin (adults) or Tylenol along with fluids, plus tincture of time.

The best way to treat this common disease is to boost your immunity so you don’t catch it or get only a mild case. You boost your immunity by getting a flu shot. The vaccine is reformulated each year, usually with 2 type A variants and one type B by the US Centers for Disease Control. The CDC bases what they tell manufacturers to put in the vaccine on their best guess of which sub-types are around and most infective. It’s egg-based, so the rare person who is truly egg protein allergic (I’ve never met one), can’t take the shot and must use alternatives (see below). But most of us do fine with only a mildly sore arm. Many claim to have “gotten the flu from the shot,” but this is not possible. Most, I think, are describing a brief aching from the body’s cleaning up the shot. Once in the past a few patients got a bad neurologic weakness called Guillaine-Barré syndrome; but that has not been an issue for over a decade now. Adults and children over 8 need only one dose each year. Children over 6 months and under 8 need a series of 2 shots at least a month apart if they have never had a flu shot before or have been 2 or more years without one. No shots for kids under 6 months; they will have some immunity from their mother still on board and hopefully the family who hugs them all get their flu shots.

Timing of the shots is an issue to consider. It takes about 2 weeks for your body to develop the antibodies after the shot. The other issue is when to get the shot because the immunity wanes and the virus changes its coat over 6 months or so. Bearing in mind that peak incidence of the infection is February-March, I usually recommend that people get their shot in late October through early December. There is some flu around in the fall, but the biggest risk in is mud season, so you want most of your protection still to be there then.

The shots do work but certainly don’t always prevent infection; in fact you still have a 75% chance of getting influenza, if exposed, even though you’ve gotten a flu shot. But your chances of being so sick you can’t work are reduced to only 60% of what it would have been if you hadn’t had it, because the shot moderates the symptoms. It works even better in the elderly and young because those groups get much sicker without the shot.

If you really can't get a flu shot because of egg allergy, or you forgot and you are now in the middle of a flu epidemic, you can take the prescription medicine, oseltamivir (Tamiflu), daily for a week or two if you are around others in a flu epidemic, or if you get the flu, to ameliorate the symptoms some. But it certainly is second best.

So get a flu shot. They are cheapest at a doctor office, special clinics, some pharmacies and elsewhere. Get one!

Dan Onion

Vienna Health Officer



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