Flu season is upon us. If there is such a thing as flu season. H1N1 started at the furthest point in time you could get from the traditional start of the flu season. It is an interesting question as to whether global warming will alter the flu season, as it has the RSV season. Classically influenza is a fall/winter disease and fall started today.

It is perhaps worthwhile to review what is known about influenza.

  1. The disease influenza, the gasping oppression, is a disease that has been plaguing humans for about 500 years. It is a predominantly respiratory infection, causing a protracted cough with fever and myalgia. The term flu is used loosely to cover almost any febrile illness, and I remain uncertain as to what a stomach flu might be. I tend towards the picky side; flu is due to the influenza virus. There are many viri that can cause a flu like illness, but only the influenza virus causes the flu.
  2. The flu is due to a virus, the influenza virus. There is influenza A and B and C. There are them what deny germs as a cause of disease, and I will admit that as an infectious disease doctor I have a vested interest in germs causing disease. After all, my job is me find bug, me kill bug, me go home.
  3. Not every flu like illness is due to the influenza virus. In a given season the influenza virus may account for around 10-15% of flu like illness in the community, although during epidemics influenza can account for 60% of flu like illnesses.
  4. Influenza kills. It kills directly, it kills by acute secondary infections, it kills by worsening underlying diseases like heart failure, it kills long term by increasing vascular events such as heart attacks and stroke. Influenza kills the young, the old, the obese and the pregnant. Deaths by influenza also depend on the virulence of the circulating strains. Some strains, such as H5N1 (the bird flu) or H3N2, are more likely to kill (60% for H5N1) than strains like H1N1 which was of moderate virulence. Influenza deaths, both direct and indirect, are difficult to measure and are at best an estimate. As an example somewhere between 151,700 to 575,400 people died worldwide from H1N1 the first year, with a mean of about 250,000.
  5. When exposed to influenza, either as an infection or as a vaccine, the body responds in part by making antibody. Roughly, the better the antibody response to the influenza antigens, the better the protection to that strain of influenza. I say roughly as it depends on what part of the antigenic structure the body responds to: antibody to some antigenic sites offer better protection to influenza than others. If you are lucky enough to respond to some highly conserved sites on the virus you could conceivably be immune to all strains of influenza.
  6. The influenza vaccine offers moderate protection against influenza. Unfortunately the antigens of the virus change year to year (antigenic drift) and decade to decade (antigenic shift), while the vaccine strains are fixed prior to a given season and may not optimally match the circulating strains. If there is a good match between vaccine and circulating strains in a healthy population, the protection from the vaccine can be high: for H1N1 it was 87%.
  7. Unfortunately those who need to be protected from the influenza virus are those most likely not to respond to the virus vaccine: the obese, the pregnant, the elderly and those with chronic medical diseases.
  8. The benefit of the vaccine extends beyond prevention of flu. Of course, if you don’t get influenza, you cannot spread it to others. If you do not get influenza, then, of course you can’t die of its complications, like pneumonia and heart attack. Influenza vaccination could potentially reduce the occurrence of sudden death, acute myocardial infarct, and stroke by 50%. Babies born to vaccinated mothers have fewer cases of influenza. Vaccinated mothers are less like to have stillborn or small babies. Not getting influenza or being vaccinated against flu has many short term and long term benefits.
  9. Influenza spread can be decreased by mechanical/environmental interventions: hand washing and masks, although these interventions have variable efficacy depending on the population studied. They are not as effective as not getting the virus.
  10. Health care workers are particularly problematic. For a variety of reasons they are likely to come to work ill, influenza can be potentially infectious before people are symptomatic, and spread in the hospital occurs, leading to true stories such as this:

    Patient Story: Spreading the Flu 4-2012

    As a reminder, we have added patient stories to meetings as a way of “bringing the patient into the room,” clarifying the context for our quality plan, and emphasizing the complexities and the importance of the work we are undertaking.

    Today’s story is about a group of patients, a nurse, and influenza. It starts with Patient #1, a 57 year-old woman admitted through the emergency department (ED) to one of our hospitals in mid-March with fever and shortness of breath. She was transferred to an inpatient unit with a mask on, which triggered the staff on the receiving unit to implement droplet precautions. Initially thought to have pneumonia, testing confirmed her symptoms were the result of influenza type A, H1N1. After four nights in the hospital, she was discharged home after an uneventful hospital stay and a flu shot.

    Patient #2, next door to Patient #1, is a 58 year-old man who was admitted in early March for a GI bleed with multiple co- morbidities. His progress was steady until nine days after admission, when he developed a new fever and respiratory symptoms. These symptoms developed on the same day of Patient #1’s admission. Influenza was suspected two days following the development of his fever, and staff implemented droplet precautions. Lab testing confirmed influenza type A. He remained hospitalized for two more days and received a flu shot before being transferred to a skilled nursing facility.

    Down the hall, Patient #3, a 77 year-old man, was admitted two days after Patient #1 for acute stroke and urinary tract infection. On day 3 of his hospitalization, he developed a fever and cough. Lab testing confirmed influenza type A. Droplet precautions were ordered with the lab test for influenza. He remained hospitalized an additional four nights and received a flu shot before being discharged.

    Patient #4, a 76 year old man, down the hall from the first two patients and around the corner from Patient #3, was admitted on the same day as Patient #1 following a fainting event at home. Due to his long-standing heart issues, he was kept overnight for observation and discharged the following morning. However, he returned to the ED three days later with continued symptoms. He was discharged from the ED only to return the next day with shortness of breath. Six hours after being readmitted, staff suspected influenza and ordered droplet precautions. His lab tests returned positive for influenza type A. After spending three nights in the hospital, he was discharged home after receiving a flu shot. The following day, he was admitted to the intensive care unit and continued receiving treatment as an inpatient for secondary pneumonia, a complication of his influenza type A infection.

    The fifth person in our story is a nurse on the unit where these four patients were admitted. She works on a nursing unit whose hand hygiene performance is currently 67%, and where 85% of the unit staff were vaccinated for this year’s seasonal flu. The particular nurse in this case, however, was 1 of only 9 on the unit who chose not to be vaccinated. Her manager stated that the reason the nurse gave for not receiving the vaccine was that she “was not convinced of the evidence that the vaccine protects patients from transmission … she said she would get the vaccine if she truly believed it protected her patients, but that she didn’t.”

    This nurse cared for Patient #1 on her first day of admission. She cared for Patient #2 on the eighth and ninth day (when he developed flu symptoms) of his stay. She also cared for Patient #3 on the first two days of his inpatient stay. There does not appear to be any direct contact with this nurse and Patient #4.

    The nurse in our story developed symptoms consistent with influenza three days after working with Patient #1 and Patient #2 (which is the usual 1- to 4-day incubation period for influenza). Due to symptoms, she only worked a partial shift that day. Suspecting her symptoms may be influenza, she used a mask until relief staff was available. She returned home and was able to care for herself without medical intervention. She was not tested for influenza and remained off work for one week. She is still undecided about receiving the flu vaccine.

  11. Because those in the hospital are particularly vulnerable to the ravages of infections, mortality from hospital acquired influenza is remarkably high: 25%.
  12. Influenza vaccine is safe as well as effective. There have been some rare complications to the vaccine: Guillain-Barré syndrome in the 1970s and the recent reports that prior vaccination may have made disease from H1N1 worse. Biologic systems are complex, but I look at vaccines as much safer than seat belts and air bags, both of which can cause injury and death. I would still prefer to be in a car accident with seat belts and air bags and work during the flu season with vaccination.
  13. Influenza vaccination for health care workers runs at best 70% in the US, which if it were my kids math grade would be cause for some ‘splanin. Doctors and nurses run a bit higher, with an 80% influenza vaccination rate in some institutions.
  14. It would be nice to prevent the spread of influenza from health care workers to patients. There is no data for hospitals, although there are nursing home studies to suggest that when staff is vaccinated against flu there is a decrease in flu in the inmates, er, nursing home patients. One retrospective study suggested that units that had higher vaccination rates had fewer cases of flu, but the definitive study has yet to be done. There is buckets of biologic plausibility to suggest that vaccinating health care workers would be of benefit to patients under their care.
  15. I have little (actually none) respect for HCWs who do not get vaccinated. We have a professional and moral obligation to place our patients first. I think those who do not get vaccinated, except for a minority with a valid allergy, are dumb asses. Here is a copy of my yearly screed over at Medscape:

    This essay is, I would like to clarify, directed at healthcare providers, not patients. Healthcare providers have no excuse to avoid the flu vaccine: they have access to the world’s medical knowledge and should be able to rise above superstition and ignorance. Yes, I too am a Dumb Ass, but for different reasons.

    I give you, slightly rewritten for 2012, a Budget of Dumb Asses.

    I wonder if you are one of those Dumb Asses who do not get the flu shot each year? Yes. Dumb Ass. Big D, big A. You may be allergic to the vaccine (most are not when tested), you may have had Guillain-Barre (most can be vaccinated safely), in which case I will cut you some slack. But if you don’t have those conditions and you work in healthcare and you don’t get a vaccine for one of the following reasons, you are a Dumb Ass.

    1. The vaccine gives me the flu.Dumb Ass. It is a killed vaccine. It cannot give you the influenza. It is impossible to get flu from the influenza vaccine.

    2. I never get the flu, so I don’t need the vaccine.Irresponsible Dumb Ass. I have never had a head on collision, but I wear my seat belt. And you probably don’t use a condom either. So far you have been lucky, and you are a potential winner of a Darwin Award, although since you don’t use a condom, you are unfortunately still in the gene pool.

    3. Only old people get the flu.Selfish Dumb Ass. Influenza can infect anyone, and the groups who are more likely to die of influenza are the very young, the pregnant, and the elderly. Often those most at risk for dying from influenza are those least able, due to age or underlying diseases, to respond to the vaccine. You can help prevent your old, sickly Grandmother or your newborn daughter from getting influenza by getting the vaccine, so you do not get flu and pass it one to her. Flu, by the way, is highly contagious, with 20% to 50% of contacts with an index case getting the flu. However, Granny may be sitting on a fortune that will come to you, and killing her off with the flu is a great way to get her out of the way and never be caught. That would make a good episode of CSI.

    4. I can prevent influenza or treat it by taking echinacea, vitamin C, oscillococcinum or Airborne. Gullible Dumb Ass cubed then squared. None of these concoctions has any efficacy what so ever against influenza. And if you think oscillococcinum has any efficacy, I would like you to invest in a perpetual motion machine I have invented. None of the above either prevent or treat influenza. And you can’t “boost” your immune system either. Anyone who suggests otherwise wants you money, not to improve your health.

    5. Flu isn’t all that bad of a disease. Underestimating Dumb Ass. Part of the problem with the term flu is that it is used both as a generic term for damn near any viral illness with a fever and is also used for a severe viral pneumonia. Medical people are just as inaccurate about using the term as the general public. The influenza virus directly and indirectly kills 20,000 people (depending on the circulating strain and year) and leads to the hospitalization of 200,000 in the US each year. Influenza is a nasty lung illness. And what is stomach ‘flu’? No such thing.

    6. I am not at risk for flu. Denying Dumb Ass. If you breathe, you are risk for influenza. Here are the groups of people who should not get the flu vaccine (outside of people with severe adverse reactions to the vaccine): Former President Clinton, who evidently doesn’t inhale. Michele Bachmann. Wait, that’s the HPV vaccine. And people who are safe from zombies. If you don’t get the vaccine you do not have to worry about the zombie apocalypse, because zombies eat brains.

    7. The vaccine is worse than the disease. Dumb Ass AND a wimp. What a combination. Your mother must be proud. Unless you think a sore deltoid for a day is too high a price to pay to prevent two weeks of high fevers, severe muscles aches, and intractable cough.

    8. I had the vaccine last year, so I do not need it this year. Uneducated Dumb Ass. Each year new strains of influenza circulate across the world. Last year’s vaccine at best provides only partial protection. Every year you need a new shot.

    9. The vaccine costs too much.Cheap Dumb Ass. The vaccine costs less than a funeral, less than Tamiflu, and less than a week in the hospital.

    10. I received the vaccine and I got the flu anyway. Inexact Dumb Ass. The vaccine is not perfect and you may have indeed had the flu. More likely you called one of the many respiratory viruses (viri?) people get each year the flu. Remember there are dozens of potential causes of a respiratory infection circulating, the vaccine only covers influenza, the virus most likely to kill you and yours.

    11. I don’t believe in the flu vaccine. Superstitious, premodern, magical thinking Dumb Ass. What is there to believe in? Belief is what you do when there is no data. Probably don’t believe in gravity or germ theory either. Everyone, I suppose, has to believe in something, and I believe I will have a beer.

    12. I will wait until I have symptoms and stay home.Dangerous Dumb Ass. Despite often coming to work ill, especially second year residents, about 1 in 5 cases of influenza are subclinical, hospitalized patients are more susceptible to acquiring influenza from HCW’s than the general population, and 27% of nosocomial acquired H1N1 died. And you will never realize that you were the one responsible for killing that patient by passing on the flu.

    13. The flu vaccine is not safe and has not been evaluated for safety. Computer illiterate Dumb Ass. There are 1342 references on the PubMeds on safety of the flu vaccine, and the vaccine usually causes only short term, mild reactions. All health care requires weighing the risks of an intervention against the benefits. For the flu vaccine all the data suggests huge benefit for negligible risk. And as a HCW, it could be argued that we have a moral responsibility to maximize the safety of our patients.

    14. The government puts tracking nanobots in the vaccine as well as RFID chips as part of the mark of the beast, and the vaccine doesn’t work since it is part of a big government sponsored conspiracy to keep Americans ill, fill hospital beds, line the pockets of big pharma and inject the American sheeple with exotic new infections in an attempt to control population growth and help usher in a New World Order. Well, that excuse is at least reasonable.Paranoid Dumb Ass.

    So get the vaccine. And pass this essay on to someone else instead of the flu. The life you may save may be your own. Or be a Dumb Ass.

  16. And this leads to my final thought. There is a tremendous amount of medical literature pointing to the safety and wide ranging benefits of the influenza vaccine as well as the morbidity and mortality that influenza inflicts on humans every year. Despite that information, when you are admitted to the hospital you have a greater than one in three chance that the HCW taking care of you is ignoring that information and going unvaccinated.

I have long been of the opinion that you judge a person by the company they keep. If your health care worker is a big enough dumb ass to avoid the flu vaccine, what other areas of medicine are they equally incompetent in? Do you want to drive in a car with no seat belts or air bag, whose brakes are of uncertain maintenance? Do you want you or your loved ones to be cared for by someone who is dumb ass enough to not get the flu vaccine, putting you and yours at risk when most vulnerable? Can you expect that person to do the rest of their job correctly when they cannot understand and implement a core competency of medicine? Not me.

Here is my suggestion. When you and yours are in the clinic or the hospital, request care only from practitioners that have had the flu vaccine. Put a sign on your hospital room door: No entry unless you are influenza vaccinated or put a copy of this essay on the door. You do have the right to refuse care, especially from a dumb ass.

I know this idea is a non-starter. Sick, vulnerable people are in no condition to potentially antagonize their providers. No one is likely to want to piss off their HCW, especially if that person holds the key to the morphine.

There is a bankrupt idea that it is OK for patients to ask their provider if they washed their hands. It never worked. I took an informal poll of patients on one of my medical floors and asked if they would ever tell their doctor or nurse to wash their hands and not a one said they would. It would be like asking your pilot if he put the wheels down as they stated a landing. Patients need to trust that we are doing what is in their best interests. When it comes to influenza vaccination, you can’t.

I do not really expect anyone will actually ask to be cared for only by influenza vaccinated providers.

But I can dream.


Of sorts. I had the opportunity to play golf with my brother and son and the time I would normally spend linking to references was spent on the links. I hope to update it, but really, you can’t search the Pubmeds?



  • Mark Crislip, MD has been a practicing Infectious Disease specialist in Portland, Oregon, from 1990 to 2023. He has been voted a US News and World Report best US doctor, best ID doctor in Portland Magazine multiple times, has multiple teaching awards and, most importantly,  the ‘Attending Most Likely To Tell It Like It Is’ by the medical residents at his hospital. His multi-media empire can be found at

Posted by Mark Crislip

Mark Crislip, MD has been a practicing Infectious Disease specialist in Portland, Oregon, from 1990 to 2023. He has been voted a US News and World Report best US doctor, best ID doctor in Portland Magazine multiple times, has multiple teaching awards and, most importantly,  the ‘Attending Most Likely To Tell It Like It Is’ by the medical residents at his hospital. His multi-media empire can be found at