Effect Measure

I’ve been asked a number of times why I am bothering to get both flu vaccines this year (the seasonal flu trivalent vaccine and the swine flu vaccine when it is my turn). I am in the older age group (last in line for swine flu vaccine) and it is my group that is hit the least hard from the swine flu virus. But there are a lot of us and we’re still being hit. I don’t know if I will be one of the unlucky few in my age group who draws the short straw or not, and I’d rather get vaccinated with an acceptably safe vaccine than take a chance in winding up having a machine breathe for me or not breathing at all. Moreover, we aren’t sure what’s going on with the relative lack of impact in my age group. It is possible (although truthfully I don’t think it is the most likely thing) that we are still being infected and shedding virus in reasonable numbers but some kind of cross-reactivity obtained in a past infection or a long history of yearly vaccinations is sparing us more serious clinical outcomes. After all, about a third of flu cases are asymptomatic under any conditions. So why care? Because it might still mean I could pass it on to family, friends and co-workers.

As for the seasonal flu vaccine, whether the seasonal flu A viruses will be a return in December or January or co-circulate with the swine flu viruses and whack the over 65 group I don’t know and neither does anyone else. Flu is unpredictable, but if the seasonal flu A strains come back, 90% of the deaths are typically in my age group. I’m not completely confident that the vaccine is highly effective for the elderly, but whatever its efficacy, it sure beats zero effect, which is what you get from not being vaccinated.

Mostly, though, I get asked the question by younger people who are (wisely) planning to get the swine flu vaccine but wonder why they should bother with the seasonal vaccine. Beside the answer that we don’t know with confidence what the seasonal influenza viruses A/H1N1 and AH3N2 will do, there is another, very good reason that applies to people of all ages. The seasonal flu vaccine is a trivalent vaccine, meaning it has three components, one of which is influenza B. Influenza B can make you plenty miserable and it co-circulates with the other viruses every winter. Last flu season about a third of flu cases were flu B (for more information on the three types of influenza, A, B and C, see a nice concise post at Vincent Rancaniello’s Virology Blog).


The green bars are flu B. And last year was not unusual. Here are the four years before that, again with green being influenza B:


There is no reason to think the swine flu will squeeze influenza B out of circulation, although with all-things-flu anything seems possible. But I think it’s unlikely and that means the seasonal flu vaccine will be providing significant protection against influenza B for whoever gets it (NB to grammar pedants: whoever is the subject of a subordinate clause; it the clause that is the object of the preposition “for” so it isn’t “whomever”. This is a pre-emptive strike. It’s the internet, after all.) That’s a reason for a person of any age to get the seasonal flu vaccine.

That’s my reasoning, anyway. I won’t say different people can’t weigh the odds differently. I’m a Bayesian so I allow subjective probabilities, but I think the evidence suggests you should move your posteriors and get vaccinated (I know; lame statistical joke).


  1. #1 "GrrlScientist"
    October 15, 2009

    one of these two vaccines was paid for through our tax dollars and thus, is free to everyone, while the other one costs $25 or something like that. can you tell me which one is free and which is not, and what low-income or unemployed people can do to get both vaccines without having to further strain their already strained budgets?

  2. #2 Anonymous
    October 15, 2009

    Please comment on this article if you have the time:


  3. #3 Kenny Easwaran
    October 15, 2009

    Is there a reason there’s a spike in all types of flu at week 17 last year, rather than just 2009 H1N1? Is that just when they started testing large numbers of cases, so that overall number of positive tests went up? That wouldn’t explain why the percent positive started increasing again at the same time.

  4. #4 Bill Sardi
    October 15, 2009

    You are expressing your ignorance. Virology Professor Racaniello has asked, “Why should anyone receive the seasonal flu shot?” His reason: 99% of the flu in circulation is the H1N1 pandemic strain and the seasonal flu simply exist this year.

  5. #5 Marilyn Mann
    October 15, 2009


    Take a look at this response to the Atlantic article:


  6. #6 Racter
    October 15, 2009

    Referring to the most recent CDC influenza surveillance report, 99.7% of all the isolates tested were influenza A. Of the type A isolates, 52.3% were confirmed as novel H1N1. Those that were confirmed as seasonal influenza amounted to a mere 0.2%. Another 1.4% were unable to be subtyped, suggesting that these were also novel H1N1. But in 46.2% of the isolates, subtyping was not performed.

    It may be reasonable enough to extrapolate the results of the isolates that were tested to those that were not, leading to the conclusion that 99+% of the influenza circulating is novel H1N1, and I’m willing to tentatively accept that this is probably the case — but when performing this sort of educated guesswork, it’s good to keep in mind that it’s still guesswork.

    It will be interesting to see whether things play out much differently in those Canadian provinces where seasonal flu vaccination programs have been suspended.

  7. #7 revere
    October 15, 2009

    Grrl: The H1N1 vaccine and the materials needed to dispense it (spray bottles or needles, vials, etc.) are paid for by tax dollars. You should not be charged, by anybody, for those things. But you can still be charged for the cost of administration, and retailers like Walgreen’s contract with vaccination outfits that do charge. So may any provider. The only thing they can’t charge for is the materials.

    Bill Sardi: We’ve discussed the NREVSS surveillance system quite a lot here, so I am not unaware (in fact have written about it multiple times) that at this point essentially the only flu A out there is swine flu. But I’ve been doing flu for a quite a while and one thing I’ve learned is that flu is unpredictable. We usually see very little of the seasonal strains around at this time of year. What we don’t know is what will happen in January and February which is the peak of the flu season normally. If H1N1 is burned out there is still a large possible pool of susceptible and there remain seasonal flu isolates out there. We don’t understand the dynamics of this disease well enough to predict what will happen. Remember, there is little cross reactivity and until 1977 we didn’t think subtypes could co-circulate. So my response to you was that I wasn’t displaying my ignorance but trying to display my reasoning. That reasoning could be faulty but it isn’t based on lack of knowledge of the facts.

    Kenny: week to week variations in flu are subject to all sorts of reporting issues, so I wouldn’t base much on them.

  8. #8 Moderately Unbalanced Squid
    October 15, 2009

    I heard yesterday that large American providers of flu vaccine are cancelling future commitments to provide the seasonal vaccine because they’ve run out. Is this true? Will there be a shortage of the seasonal vaccine this year?

  9. #9 revere
    October 15, 2009

    MUSquid: As far as I understand it at this point, CDC is saying there will be no shortage, just supply chain hiccups. As for next year, that decision is made by an int’l committee with WHO. They recommend what goes in the vaccine and the companies follow it because that’s what will be bought. That decision is usually made in Feb., I think.

  10. #10 Don S
    October 15, 2009

    Several interesting conversations going here at the same time!

    First cost of vaccination to individuals – low income individuals can always get their vaccines for an administration fee only via Medicaid and the elderly through Medicare. Insured individuals often (not always) have it covered. True, there is an issue for seasonal influenza for those who make enough that they do not qualify for Medicaid yet are still poor, yet those are often the individuals who could least afford to miss a week or more of work with influenza.

    Second the efficacy of vaccination against seasonal influenza.

    Let us start with a sense of the cost of seasonal influenza. Sticking to America alone there is the well known 35 to 40K (roughly) deaths per year. There is also the roughly $4.6 billion in direct medical costs and the roughly 111 million missed workdays and indirect economic costs. All together dollars and cents of direct and indirect costs are estimated to be about $12 billion a year, give or take a few depending on the severity.

    Big bucks and worth reducing but the question of how is indeed an open question. Problem is that high risk individuals often respond to the vaccine the least well. They also are not who spread it the most. The more effective strategy would be to target not those who are most likely to get the sickest, but those who spread it the most and who respond to the vaccine the best: target school aged children and their parents thereby protecting higher risk individuals by preventing their exposure in the first place. I think we are slowly moving to that model.

    Third, the subject of this thread itself. As may be apparent to some, I am obsessed with surge capacity this year. It’s sort of like New Orleans before Katrina – we can handle a Cat 3 hurricane but what is coming may be a Cat 4 or 5. Seasonal flu may not be a major component of what comes but it will be some part of it – every drop over the top of the dike is a major problem and any of those cases that are preventable must be prevented. The price of needing to be hospitalized with seasonal influenza, to the individual and to the system both, may be higher than usual even if the risk of that hospitalization is significantly less than usual. Get both.

  11. #11 bumblebbrain
    October 15, 2009

    Our local city health department had a free seasonal flu vaccination clinic last week (I’m in California). I’m not sure how common that is but we got ours that way, and I’m hoping that they offer the H1N1 that way as well – no information on that so far. It wasn’t a fast thing – about 2 hours of waiting in lines and filling out forms, but at least we got the vaccine and didn’t pay a cent. I’m not sure why this would be, but they preferred to give the nasal spray to most people, and reserved the shots for specific types of people (over 50, under 3, etc). Perhaps it was faster. They were very organized and had lots of volunteers helping to process people, so our 2 hour wait time was remarkably efficient.

    It is definitely something to look into if you’re broke and have time to spend doing it.

  12. #12 Flu-ctuation
    October 15, 2009

    I appreciate your posts about the swine flu and about the vaccinations. Since you post about something that I was having a question about for quite some time, perhaps I may kindly ask you for a comment. The seasonal flu vaccines for the past few years have also had some H1N1-strains covered, and I have heard that a doctor said that having all seasonal vaccines from the past few years would provide a (small, but still not insignificant) cross-immunity for the new H1N1 swine flu strain. Which would also explain why older people aren’t hit as hard as younger ones, who don’t usually receive the annual vaccine. What do you think about this?

  13. #13 Don S
    October 15, 2009


    Any idea why we always seem to see a decrease in ILI outpatient visit percentage in January each year? Is that less ILI or more other visits or both?

  14. #14 revere
    October 15, 2009

    Flu-cutation: The data are conflicting. Some suggest very little cross-reactivity and some say prior seasonal vaccination is slightly protective. These are published studies (CDC’s MMWR and BMJ). The still unpublished Skowronski data from Canada even suggests getting last year’s seasonal vaccine might increase your swine flu risk. There is some skepticism about the last of these, but we haven’t seen the data so I am withholding judgment. It remains a puzzle why us older folk don’t get sick as often from this H1N1 as younger ones do as we have all been exposed to H1N1s since 1977 (and for the older of us, before 1957). Since the 1977 returnee was intimately related to at least one strain around in 1950 the explanation isn’t that it is completely different, but I suspect there was more than one antigenic variety in 1950 (we know there were at least to co-circulating strains in 1951) and that this might be the issue. If you got the right one in the pre-1957 period yo9u have some protection, especially if that was the one that circulated through 1957 but not the one that came back in 1977 (as a result of a lab accident). But it remains a tantalizing mystery.

  15. #15 Kimball Atwood
    October 15, 2009

    ” ‘whoever’ is the subject of a subordinate clause; it’s the clause that is the object of the preposition ‘for’ so it isn’t ‘whomever’.”

    Right! I’ve thought of mentioning that from time to time, but never got around to it.

  16. #16 khan
    October 15, 2009

    I just got the seasonal. I’m 59. Should I try to get the H1N1? Should I wait until after targeted groups get it? Should I just wait until it shows up at the grocery pharmacy?

  17. #17 revere
    October 15, 2009

    khan: My advice is, yes, get the swine flu vaccine when your turn comes up.

  18. #18 Snowy Owl
    October 15, 2009

    Hi Revere,

    As you know flutrackers.com is international.

    I have to share solutions for so many countries leaders on alternatives of vaccinnes since they will not have them.

    Prevention seems to be the pedagogy chosen, but as for reducing the viral replication except tamiflu and relenza they urge for some alternatives.

    My question is are they traditional or alternative solutions to reduce the replication once one is infected.

    From Africa and India, so many people are concerned.

    Thank You

    Snowy Owl

  19. #19 revere
    October 15, 2009

    Snowy: It’s a good question but I don’t have the answer. I don’t know much about alternatives and which ones might or might not be effective. It is likely that many don’t work but some may but since they haven’t been tested you don’t know which ones they are. The problem is that some of them may have adverse effects and no benefits or lead some people to use them instead of an effective vaccine, when that’s available.

  20. #20 Flu-ctuation
    October 15, 2009

    Hello revere,
    thanks for your comment. Interesting, I thought that maybe a combination of several seasonal flu shot would be the equivalent to whatever gives older people immunity. Would have made some sense. But if you describe the merit as little or slight, it doesn’t seem to be a substitute for the proper vaccine. Thanks.

  21. #21 Paula
    October 15, 2009

    Revere, you write, re older persons getting sick from this flu less often, so far, that you think there may well have been “more than one antigenic variety in 1950 (we know there were at least t[w]o co-circulating strains in 1951) and that this might be the issue. If you got the right one in the pre-1957 period yo9u have some protection, especially if that was the one that circulated through 1957 but not the one that came back in 1977.” Why would this protection not have shown up, except for 33 percent of older persons, in the crossreactivity studies reported in the 9-10 NEJM? I’m still hoping, both as an older person and for the sake of other older persons, of course that there is such protection, but what is being done to look further into these “tantalizing mysteries,” as you well call them?

  22. #22 Ron Law
    October 16, 2009

    The massive increase in all positive flu tests in week 17 is simply due to ramped up testing… if one turns the volume up on your stereo you get much more noise… that’s what’s happened with this panic flu. Wait till the vaccine has been rolled out… testing will ramp up again to exclude H1N1 so they can say how marvellous the vaccine was. For the record, over 100 million people have already been infected with this pandemic wannabe.

  23. #23 A real pandemic
    October 16, 2009

    Ron, what testing? Michigan has said they are no longer testing because it is not worth the 250 dollars per person. Many states are following suit. I don’t see anyone panicing over this “wannabee” pandemic.

  24. #24 revere
    October 16, 2009

    Paula: It remains a mystery. I was just speculating. Since the geographic distribution of the two varieties of H1N1 was different (Canada, New England and the UK had one, the rest of Europe and the US another) it is capable of being tested to some extent. But there are other possible explanations. A colleague believes it has to do with how many times you were immunized and how early, etc.

  25. #25 Curious
    October 16, 2009

    Okay, so this is interesting:

    Just got back from my allergist, who treats my asthma. He told me he and all of his peers in two different cities are NOT recommending the swine flu shot right now. His reasoning: “The shots are made in China and other foreign countries. There isn’t as much oversite there as in the U.S. Who knows what’s in them.”

    I was aghast — his patients are asthmatics after all. And though I only know what I read on the internet, I found that statement to be alarmingly misinformed.

    I am, of course, getting the shot as soon as it becomes available to me. But holy cow.

  26. #26 revere
    October 16, 2009

    Curioius: It’s appalling. No vaccine for the US are made in China. The Chinese make their own via company called Sinovac. Refer him to




    for the companies that manufacture the vaccines (European and Australian, the same ones that make many of the drugs and biologicals he uses in daily practice).

  27. #27 Techskeptic
    October 16, 2009

    Where do i go to find the following data (there is sooo much out there its really hard to resolve):

    infection and death rate of unvaccinated population
    Infection and death rate of vaccinated population

    I’m just talking about flu shots here. I dont really care what country (but it would be interesting to know if it is different from country to country and if that has to do with vax take up rate). I already have a good handle on the teeny complication rate.

  28. #28 Racter
    October 16, 2009

    As you appear to be aware, there is a plethora of studies on the effectiveness of influenza vaccines, and rates of infection and deaths are commonly used as endpoints. But this is not nearly as simple a matter as one might suppose. Does “infection” refer only to laboratory confirmed influenza, or does it include “influenza-like illness”? How does one differentiate between those deaths which are caused by influenza and those in which influenza was present, but accompanied by another underlying condition which might have resulted in death even in the absence of influenza? Different researchers may handle those sorts of things differently, and I don’t know where you’d go to find it all neatly sorted out.

    One thing to keep in mind is that some of those most vulnerable to influenza are not even good candidates for vaccination, and must rely for their protection on the immune status of those around them. Vaccinating a group of healthy people may not result in a significant reduction in mortality in that group, but if that group happens to be family contacts of one of those especially vulnerable non-vaccinatable individuals, it may result in a reduction in mortality nonetheless — one that isn’t going to show up in the data if you’re just using the “vaccinated versus unvaccinated” approach. See what I mean?

  29. #29 john a
    October 16, 2009


    My wife is pregnant and we live in Europe where there will only be the GSK vaccine (containing adjuvant AS03) available. I am in a real dilemma because it appears that swine flu is much more serious for pregnant women (2 deaths in the UK in the last week). However it also appears quite clear that there is a real risk of nervous system damage to the fetus (13 offspring from 7 litters were missing a reflect) see GSK documentation:

    “There was one unexpected death in a maternal rat: however, this was judged unrelated to the vaccine. Treatment of maternal rats did not adversely affect their clinical condition, bodyweight or food consumption throughout the study. Mating performance, fertility of maternal rats, and length of gestation or ability to give birth to a live litter were unaffected. Embryo-foetal survival, growth and development were not affected by vaccination. In neonates, the reflex development was unimpaired, but among offspring from dams treated with AS03 13 offspring from 7 litters did not show the air righting reflect before day 21 of age and this effect may be related to treatment. However, AS03 did not affect the attainment of the surface righting reflex or the ability of the offspring to show startle response reflexes or the pupil reflex. No abnormalities were evident on macro pathological examination of the offspring. This is considered a suitable study to assess the reproductive toxicity of the vaccine.”

    Also regarding young children the analysis below is pretty convincing – also from a comment on Susan Chu’s blog:


    “Weigh benefit against possible cost:

    If the event was not bad luck and there is a 1 in 400 of a serious adverse pediatric event from arthritis to stroke, the question is what is the chance of dying from H1N1 for an otherwise healthy child. I believe that about 2/3 of the child deaths thus far are associated with underlying conditions, so there have been about 25 deaths of children without underlying conditions in the US. If there are 150 such “healthy” pediatric deaths by the time the flu is through, and with about 82 million under 19, we are probably seeing a death rate of 2 per million among all children, or a bit more if “healthy” deaths are taken to healthy children. So if a death rate of 2.5 to 3 per million is likely vs. a 1 in 400 chance of a serious adverse event, it would appear the damage from vaccinations with adjuvants (not in the US but elsewhere) is a lot higher than not being vaccinated. For 10 million kids vaccinated, we would expect 25,000 serious adverse events vs. 25 deaths. This is speculative, but if the rough magnitudes are right, it would suggest many parents in the UK, Europe and Canada are rational if they refuse to have their kids vaccinated – and maybe themselves too? Even if the real adverse rate from vaccines is a tenth as much (1 in 4000), it is still 100 adverse events vs. 1 death. “

  30. #30 Miss Cellania
    October 16, 2009

    OK, go get whatever vaccine is available to you. I just got over six days of hell. After two kids came down with flu, I was flattened worst of all. Three days of delirious fever and chest pains followed by three days of a mysterious quantum gravity effect on my head. Plus digestive system troubles I don’t even want to think about.

    You don’t want to take a chance with whatever kind I had.

  31. #31 revere
    October 16, 2009

    john a: Susan and I disagree on the risks from squalene and I don’t think there is a way to tell at the moment. So it’s a matter of judgment and my judgment is that I would advise my daughter to get the vaccine, adjuvanted or not (she has been pregnant 3 times, although thankfully not at the moment; but she had one fetal demise late in pregnancy so I know how devastating this is and I appreciate your concern; it was not related to a vaccine and it happens much more often than we think) . My view isn’t based on any one particular study but what I consider the weight of the evidence, including experience with squalene adjuvanted vaccine over the years and experience with flu over the years. There are putative adverse fetal outcomes for women infected with flu while pregnant, too, so that’s another factor. Susan is very smart, well informed and has taken a special interest in this issue. I don’t at all dismiss the points she makes. It’s just that I have come to a different conclusion.

  32. #32 Don S
    October 16, 2009

    Just to forewarn you of what you WILL here in the next several months:

    There will be millions of people vaccinated and of those millions of people some will happen to have some adverse event happen in the one week following the shot – lost pregnacies, rare diseases, etc etc, just by chance. People will claim that the vaccines caused these rare events and some people will honestly believe it – they were fine, they got the vaccine, next week a rare disease happened to them, ergo the vaccine caused the adverse event. The CDC will state accurately that “we have no evidence of a causal link but will study it – we cannot at this time rule it out” , because as good scientists that is the accurate thing to say. They will of course collect the data and in three months state that “the evidence does not support a causal link” and the tin foil hatters will cry cover-up. Many in the public will hear that as well they don’t really know do they?

    Every time. Happens every time.

  33. #33 Ron Law
    October 16, 2009

    Techskeptic, there are actually very few studies that have been undertaken regarding flu vaccine efficacy. Google jefferson, cochrane, infuenza vaccine efficacy.

    Start with this editorial by Dr Jefferson who is the co-ordinator for reviewing effectiveness of influenza vaccines. http://www.bmj.com/cgi/content/full/333/7574/912

    He starts by asking the question, “Each year enormous effort goes into producing influenza vaccines for that specific year and delivering them to appropriate sections of the population. Is this effort justified?”

    He ends with “Evidence from systematic reviews shows that inactivated vaccines have little or no effect on the effects measured

    Most studies are of poor methodological quality and the impact of confounders is high

    Little comparative evidence exists on the safety of these vaccines

    Reasons for the current gap between policy and evidence are unclear, but given the huge resources involved, a re-evaluation should be urgently undertaken.”

  34. #34 revere
    October 16, 2009

    Ron: Jefferson has turned into sort of a Cochrane crank, but the issue he was addressing was the efficacy in the elderly. Regarding efficacy in general there is quite a lot of data from clinical trials and they were reviewed by one of the world’s authorities on vaccine efficacy, Elizabeth Halloran, a biostatistician. We discussed it here.

  35. #35 Don S
    October 16, 2009

    John A,

    I have no personal knowledge about adjuvant in influenza vaccine and fetal development. I do know that if it was my daughter I’d take the remote possibility of a delayed human equivalent to the air righting reflex in return to the definite decreased risk of my daughter dieing, or being hospitalized, and the real risks both of those would entail to my future grandchild. To me that is an easy question.

    As to the quote from Susan Cho’s blog: She asks a wrong question. The question must be what is the risk of harm from the vaccine vs what is the risk of harm from preventable influenza (not only deaths) to a child who you presume (perhaps incorrectly) has no “pre-existing condition”. On the one hand you her “what if” assumed for the sake of discussion one out of 400 chance of some adverse event from the adjuvant, from minor to serious but transient, to severe and chronic. OTOH you have the defined real risk of the adverse event of hospitalization of about 1/200 for a disease that may very well infect 40% of the population which gives not much different than that 1/400 hypothetical risk. Of those kids about 20% will end up in the ICU, and and those perhaps 15% will die. Hmmmm possible what if we imagine its real of 1/400 from mild to serious transient to chronic, vs about the same but defined real and beginning with serious enough to require hospitalization and reaching into death… again, I know my choice.

  36. #36 g336
    October 17, 2009

    For the first time, I got the seasonal shot, and I’ll be lined up to get the H1N1 shot.

    Reason why: Some public health expert (may have been Revere or DemFromCT) made the point that herd immunity pertains to flus as well as to other communicable diseases. Thus, by my value system that places duty before desire, vaccination becomes a public health duty on the part of individuals, as with hand washing before preparing food and keeping one’s household garbage in covered containers.

  37. #37 Paula
    October 17, 2009

    This site can keep us sane. But out in the real world, my neighbor whose kids have “a cold” and whose “allergies are bad this week” wanted to visit (instead we walked around the block); the local hospital advises “surgical masks” to visitors; the supermarket retains its policy of warning employees against using sick leave. And the U.S. won’t “risk” adjuvants! even as vaccine production gets farther behind.

  38. #38 Texas Reader
    October 17, 2009

    I agree with g336 that there is an ethical/moral issue here. Those of us who are healthy should get the vaccines as they dramatically reduce the risk we will get sick, and thus reduce the risk we will transmit the illness to someone whose body can’t handle it due to immune suppression from disease, chemo, age, etc. Since adjuvants have been used for years in Europe with no scientific evidence of harm, and since adjuvants allow use of less of the vaccine in each injection and thus more doses being available, I see that as a moral issue as well – we should use adjuvants to we can distribute more vaccines.

    I’m an admirer of Jesus as a philosopher and his “love thy neighbor” ethic comes into play here – particularly since there is no legitimate and significant risk to each of us from taking these vaccines.

  39. #39 Mike Dark
    October 20, 2009

    Thanks for the posts Revere,

    My 8 year old currently has the flu, should he still get any flu shots as they are available? Or is that a waste now that he has already been infected with the virus?

  40. #40 Hank Roberts
    November 30, 2009

    How do we old guys know when it’s our turn?

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