epidemiology
revere | October 22, 2009A reader (h/t MVD) sent me this link to a "CBS News Exclusive," Study Of State Results Finds H1N1 Not As Prevalent As Feared. As far as I can see the main aim was to raise CBS News's profile and gain readership. That's what news organizations do. We hope they do it by good journalism. I think this is an example where the reporters just didn't have enough knowledge of what they were reporting and put the wrong spin on it.
The central claim is that CDC stopped testing for swine flu hastily and without advance notice to the states:
If you've been diagnosed "probable" or "presumed" 2009 H1N1 or…
revere | October 19, 2009Monday morning, start of week three of the official flu season (which began October 4). CDC's scientific spokeswoman on the flu, Dr. Anne Schuchat has said we are seeing "unprecedented" flu activity for this time of year, including an unusual toll in the pediatric age group. What does "unprecedented" mean? It's not very specific on what precedents are included, but if we confine ourselves to the three years before this one, we can get a good idea of just how unusual this flu season is. This week CDC unveiled a new graphic for their Emerging Infections Program (EIP) (I liked the old one better…
revere | October 18, 2009We've been traveling again (and offline), so we'll limit this to a few comments to put recent news into the context of things we talked about here recently (an excellent up-to-date status report can be found by DemFromCT at DailyKos). A good article by Rob Stein of the Washington Post highlighted some of the increasing anxiety of clinicians as flu season ramps up with pandemic swine flu in the northern hemisphere. Stein's article is quite long, but I have snipped a few things from it:
Although why a minority of patients become so sick remains a mystery, new research indicates that H1N1 is…
revere | October 11, 2009If you are hesitating to be vaccinated for swine flu this year, perhaps this post will help you make up your mind. If it does, I hope it pushes you to get vaccinated, but whatever persuasion we attempt here will only be from a recital of what we know of the epidemiology of this pandemic. Because it is the different epidemiology that is the main feature, not the clinical characteristics or the virulence of the virus. So far this looks pretty much like a standard influenza A virus -- except for the epidemiology. Since I'm an epidemiologist, you might expect me to think this is important, and I…
revere | September 27, 2009Flu season has started in earnest, even though it's not "officially" flu season until week 40 (first week in October this year). How do we know it's flu season if we don't test everyone and can't count flu? We use a surveillance system. The flu surveillance system has lots of moving parts and five or six components (or as many as nine, depending on how you count). None of them tell us exactly what we want and putting the different pieces together can sometimes be like the blind men and the elephant. But the system does work better than you'd think and it's undergoing modifications and…
revere | September 13, 2009At the beginning of September CDC initiated a new system for monitoring influenza activity. We reported last week that the old system ended on August 30 and that we were now into the new flu season. We even titled the post, "End of Flu Season." To paraphrase Mark Twain, the reports of the death of the 2008 - 2009 season may have been exaggerated. Well, not really, but the advent of the new system caused some confusion, at least for us, and we think we should clear it up.
There are several interconnected issues here. One is that the way trends in influenza will be monitored has been changed…
revere | September 10, 2009Flu season is over. Before you heave a sigh of relief, I'm talking about the (official) 2008 - 2009 flu season, which ended August 30 in week 34 or the calendar year. Welcome to the new flu season, the one called 2009 - 2010. It promises to be, well, "interesting."
Not that the one just concluded wasn't interesting. Indeed before we get done analyzing the data already collected it's likely to be the most informative in flu science history, partly because we have tools we never had before, partly because we have information gathering and handling capacity we never had before. But mostly…
revere | September 3, 2009When I tell people I am an epidemiologist, most of them think it means I'm a skin doctor. I'm not (although the skin disease specialty is much more lucrative). Instead I study patterns of disease in populations and use what I see to try to figure out why the observed pattern rather than another. Since I'm a cancer epidemiologist I usually do large, highly systematic studies that often take years to execute and analyze, but some epidemiologists do much more immediate "shoe leather" epidemiology, investigating disease outbreaks. They are like disease detectives and we can often learn a…
revere | September 2, 2009Yesterday one of the questions we asked was whether swine H1N1 would replace seasonal viruses this season. In previous pandemics one subtype completely replaced its seasonal predecessor: in 1957 H2N2 replaced the H1N1 that had been coming back annually at least since 1918; only 11 years later, in 1968, a pandemic with H3N2 replaced the H2N2. H2N2 is no longer circulating but in 1977 an H1N1 returned and has been co-circulating with H3N2 since then. This was a new situation. We could ask why this hadn't happened before with H2N2 and H1N1 or H2N2 and H3N2 or all three together; or we could ask…
revere | September 1, 2009It's not Labor Day yet, but I guess the Reveres have to consider their vacation over. We're all back at our respective home stations. We admit that not watching flu evolve daily was a relief, although we did sneak peeks when we weren't supposed to. But it also proved to be like the stock market. The daily ups and downs sometimes obscure the bigger picture. So what does it look like now?
We have two contradictory impressions. One is that the pandemic has continued to develop in a very robust fashion. So it's a dynamic picture of change. The second is that it looks like a normal pandemic, just…
revere | August 9, 2009The other day we did something we don't like to do when talking about flu, we made a prediction. We predicted a bad swine flu season in the fall in the northern hemisphere. The history of flu epidemiology is that making predictions is dangerous. Flu has the ability to make fools out of anyone, regardless of expertise. One commenter in particular disdained the risk we took as being no risk at all. It was perfectly obvious to him (or "anyone paying attention") that next flu season would be a swine flu horror show. It may well be, and then this commenter will certainly gloat and perhaps have…
revere | August 6, 2009Making predictions about something as unpredictable as flu is foolhardy. I rarely (if ever) do it, but I'm going to do it now. I am predicting a bad and early H1N1 swine flu season in the northern hemisphere next fall and winter. The reasons for this departure from our usual custom is a paper in Nature from 2007 I just re-read. It's entitled "Seasonal dynamics of recurrent epidemics" by Stone, Olinkyl and Huppert from Tel Aviv University and it appeared in vol. 446, pp 533-536, 2007 (doi:10.1038/nature05638; html version here, if you have a subscription). The paper isn't specifically about…
revere | August 5, 2009I have a reflexive skepticism about some conventional flu wisdom. There's so much about flu we don't know and even more we think we know that we find out we're wrong about. But skepticism is an occupational hazard of epidemiologists. Our training and practice focusses on detecting subtle biases that can produce misleading interpretations of data. When it comes to the commonly recommended personal protective measures for pandemic flu, our skepticism is all the greater since there is so little data to be skeptical about. The lack of data isn't an accident. If you think hard about it, you can…
revere | August 4, 2009Of the three main modes of infection for flu -- transmission by large droplets, transmission by tiny suspended aerosols, transmission via inanimate objects (also called fomites) -- it is the last that is the least certain but garners the most attention in the form of hand hygiene, disinfectants and now, fear of magazines and toys in emergency department waiting rooms and acute-care clinics in Canada. Here's the lede from an article in the Montreal-Gazette:
All magazines and toys should be removed from emergency department waiting rooms and acute-care clinics to reduce exposure to human swine…
revere | August 3, 2009There's a swine flu pandemic well underway and efforts are being made to reconstruct how it started. But almost everyone who has been following this knows it's not the first time a swine flu virus has transmitted from person to person. In 1976 in Fort Dix, New Jersey there were a couple of hundred cases, with 13 hospitalizations and one death from an H1N1 swine flu virus. The public health response was the infamous vaccination campaign that reached 44 million Americans before being ignominiously halted in the face of two facts: the feared swine flu outbreak never got out of Fort Dix; and as a…
revere | July 28, 2009CDC wants us to get vaccinated for flu every year. Always for seasonal flu, and this year, if there is a vaccine available, for swine flu. They want us to get vaccinated because they think the vaccine works and they want to prevent people from getting influenza, always a dangerous and unpredictable disease, even if most of us usually escape with just a flesh wound. CDC backs up its recommendations by a quite a few scientific studies demonstrating the vaccine is effective, citing figures that the vaccine is 58% effective or 91% or effective or some other number, depending on what group is…
revere | July 27, 2009CDC's Advisory Committee on Immunization Practices (ACIP) recently rolled out their 2009 Recommendations. It's for seasonal flu, for which a vaccine exists, not for swine flu, for which there is (as yet) no vaccine. There is a lot to say on the subject of vaccines (see what we've said over the years under the vaccine category), but this seems like a good time to review some basic terminology, including what is meant by vaccine efficacy or effectiveness and how it is measured or estimated. There's a lot to say, so we'll split this into two posts, and in this one we'll go over some terms and…
revere | July 11, 2009It's Saturday and it's summertime and Mrs. R. and I are still in the city. OK with me. I'm a city boy and find it easiest to maintain upright posture on asphalt, but my bride of 37 years likes the beach, so most summers we go off for a few weeks to the seashore (speaking littorally). It's down south where the water is warm but I still spend a lot of time inside in air conditioned splendor, listening to music and reading. Mrs. R. props herself up at the earth - water interface with her own pile of books, far from other people and the hazards of pathogenic viruses. It turns out, not really.…
revere | July 6, 2009Flu virus is opportunistic. It takes advantage of any weakness. Seasonal flu picks on the very old and the very young, but pandemic flu has found us old folks tough and the younger amongst us quite tasty. No natural resistance seems to be a flavor enhancer. And pre-existing medical conditions? Quite delectable. So how full is the menu in the prime age range? CDC has just released one of their Quickstat summaries based on household interviews with a sample of the civilian, noninstitutionalized, adult U.S. population. The question the sample was asked was whether a doctor or other health…
revere | July 5, 2009I have a lot of respect for civil servants. It's a noble task, nobler than what most of us do. But there are times when I just want to shake my head. The UK government has not exactly distinguished itself in the swine flu area, first putting pressure on WHO to hold off declaring a pandemic, then looking the other way when cases started to skyrocket in their backyard, and now . . . well, it just makes me want to shake my head:
Health minister Andy Burnham told the House of Commons yesterday that over the last week a “considerable rise” in H1N1 with several hundred new cases every day.
“Cases…