Influenza This Year in Maine
Dan Onion, MD, MPH
Mt. Vernon/Vienna Health Officer
Winter is coming and so is influenza. Last year we had a bad year and there was a lot of bad press about immunizations, so let's review this annual epidemic and what we know so far this year.
Influenza is an infectious disease of the upper and lower respiratory tract (nose, throat, breathing tubes and lungs themselves) caused by an influenza virus. Two major types of influenza infect humans, A and B. "A" types cause most of the disease, injury and death; "B" types are less common and more benign, but are still hard on, and sometimes fatal, to babies and the elderly. Influenza viruses survive over the centuries because they change their coat every few years. Those are, on Type A viruses, surface proteins called hemagglutinin (H) (with subtypes 1-5), and neuramidase (N) (subtypes 1 and 2), against which our bodies make effective antibodies when we are infected or immunized. By changing those coat proteins through genetic natural selection every few years, the slightly different flu virus becomes more infectious because people haven't been previously exposed to that version.
To treat this common disease, boost your family's immunity with a flu shot every year, so none of you catches it or maybe get only a mild case. Years, when most of us have already been infected by and/or immunized against the circulating H/N combination types, cases of illness are fewer and less severe. The US Centers for Disease Control (CDC) makes an educated guess each year about which recent subtypes are going to predominate, and incorporates 3 or 4 of those into vaccine manufactured each fall. The vaccine is 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 available alternative vaccines.
When the virus changes its coat, as it always does, and/or the US CDC hasn't guessed right, and/or we haven't done a good job of immunizing everybody, then we have worse epidemics. Their severity is usually measured by elementary school absence rates over 20%, higher than average emergency room and office visits for "influenza-like" illnesses, hospitalizations, and deaths.
When given the standard shot into our arm muscle, most of us do fine, suffering at most a mildly sore arm for a day or two. Many claim to have “gotten the flu from the shot,” but this is not possible because there is no live virus in the shot. Most, I think, are describing an aching from the body’s healing up the injection site and getting rid of the dead virus parts, thereby enhancing new antibody formation; that's why the shots work.
The US CDC monitors and regularly reports vaccine "efficacy", calculated as the percentage of people who, after having had a flu shot, later have a worrisome enough illness to prompt a medical visit. But illness visits could also reflect unusually easy access to medical care, and/or other factors. And those numbers are from the same 5 states every year, never Maine. Last year that "efficacy" was only 40%; it usually is around 50%, but occasionally is as high as 60% and rarely as low as 10%. Publicizing only the "efficacy" statistic seems quite misleading. I'd rather they emphasized hospitalization and/or mortality rates, both much "harder" outcomes and calculated for all states. Last year, Maine hospitalization rates for flu were almost 70% higher than in the previous year, confirming a bad season.
Important things to know, understand, and recognize:
•Influenza is not a viral cold (sore throat, under 100°F temperature degrees, and the patient still able to function). Nor is it gastroenteritis , predominantly nausea, vomiting and diarrhea from gut germs, which we often also call “flu.”
•The vaccine: This year the vaccine is directed against 3 (trivalent) or 4 (quadrivalent) types: influenza A/H1N1, A/H3N2, B/Colorado and B/Phuket. And we have designer vaccines with the added 4th virus' proteins at quadruple doses, and also with "adjuvants", all to enhance the effect for older or other high risk people. Childhood vaccines for ages 6 months to 8 years old are similarly specific to that age group and usually require two doses. The vaccine can also be given by nasal spray. So far this year, Maine CDC graphs (below) look good with only 34 cases in Maine. But last year at this time, things looked similarly good, so there's no telling for sure. Even if the vaccine match turns out less than ideal, you should get it and not let the perfect be the enemy of the good.
•Three ways people get sick with the flu and to watch out for:
1. Rapidly super sick patients with overwhelming viral pneumonia: Usually young people, mostly teenagers and young adults. They get sick one night with chills, often have a fever over 101, become prostrate (flat out sick) within hours, always have cough, which may or may not produce sputum; their lungs fill with fluid making them short of breath; they can get confused, turn blue and can die within hours if not hospitalized. If you see these signs, get to an emergency room ASAP, DO NOT DELAY!! Rare, but extremely dangerous.
2. Another group in trouble with delayed complications: especially in toddlers and elderly, who get the usual flu symptoms with fever over 101°, productive cough, feel rotten all over, may have some vomiting (rarely diarrhea), who then develop a secondary bacterial pneumonia. They start to get better after 3-5 days then relapse back with high fever, get sicker again, with more cough, more sputum, if not too weak to produce it, and can die in a few more days if not diagnosed and treated with bacterial antibiotics. Get them to the emergency room as soon as that regression to bad happens.
3. Finally, the rest of those with influenza, have sore throat, fever/chills, cough, feel lousy, often still try to work, then gradually improve over a week and get back to normal within 7-10 days.
•Effective antiviral drugs that help those in groups 2 and 3 above: oseltamivir (Tamiflu) 75 mg and several similar drugs work to ameliorate severity and complications if started within 48 hours of symptoms. Many clinicians will want to test a throat swab before prescribing these but when the flu season gets bad, most will figure hoof beats mean horses and prescribe it even over the phone if your symptoms fit. These drugs also work at lower doses to prevent having flu or at least reduce its complications when a family member has it.
•Think of your friends and neighbors. Don’t work or visit with them when you are sick, if you can help it; not 100% effective because you are spreading the virus a couple days before you get really sick, but worth doing.
Now, late October-early November is the time to get a flu shot. Earlier immunization risks getting the flu while the flu is still peaking in March and April (see 2nd graph below) as the immunization begins to wane 6 months after the getting it. Getting a pneumonia immunization (pneumovax), if you are due, is a good idea too, especially for older adults, because complicating pneumococcal pneumonia (group 2 above) causes many flu deaths. I had my flu shot 2 weeks ago in mid-October, which should protect me into April. So please get yours!
There is some hope that this annual dance will change soon. After decades of trying, the first universal flu vaccine, a nasal spray, is about to enter its first human trials. It appears to be able to generate immunity to parts of the virus that are the least variable from strain to strain and thereby protect against all human influenza strains. That would get rid of all this trying to guess which flu strain will be the problem next year.
(For more information, see: https://www.cdc.gov/flu/about/season/flu-season-2018-2019.htm)
Maine Cases This Year as of November 24, 2018
Maine so far this year compared to Last Year (week 0 = January 1-7)