With Permission: SIB Swiss Institute of Bioinformatics,
Philippe Le Mercier, ViralZone.
My Facebook feed got me going today. I get the Mayo Clinic feed since I consider their clinical care and some of their research to be the best in the world. Of course social media is much less rigorous and sometimes it comes down to just advertising and promotion. That was my assessment of the link to this document this morning. It is a business document that purports to give advice on how to decrease your chances of a respiratory infection this winter. Some of that advice is given by a Mayo Clinic Infectious Disease specialist and a Cleveland Clinic family physician. There was one number I had not seen before and that is the Number Needed to Treat (NNT) for the flu vaccine is 40. Forty people need to be vaccinated to prevent one case. The advice is the usual set of homilies about respiratory infections including get the flu vaccination, wash your hands, sneeze into your sleeve, take care of yourself and stay home of you are sick. In other words, there is no way in hell that you are not going to get sick at least once this winter.
Our continued 1950's approach to viral infections remains a mystery to me. Certainly there are technical problems with trying to design vaccines for over 200 viruses that can cause the common cold. But the reality is, vaccine design for influenza virus - easily the most lethal of these viruses is obviously not so hot. As far as I know, vaccines for the most common of the cold viruses - Rhinovirus - is non-existent. Anti-viral medications for respiratory viruses are more controversial. Looking at the most popular one Tamiflu or oseltamivir. The NNT to prevent one death may be 1,800 - 3,200. The NNT to prevent one hospitalization may be 97 to 142 depending on criteria. The NNT group suggests somewhat better NNTs of 36 and 83 for preventing a culture positive case of influenza and preventing pneumonia respectively. Contrast that with the NNT for antidepressants of 5-10 as determined by Leucht, et al (2) in their comparison to other medications for various medical conditions. And you thought antidepressants were ineffective?
Infectious disease respiratory virus research is a goldmine for all of the Luddites out there. There are a number of web sites that provide free access to just about everything you ever wanted to know about every virus known to man. The viral particle shown at the top of this page is the order that contains Rhinoviruses one of many common cold viruses and one of the viruses that may be responsible for the expression of asthma in predisposed individuals or exacerbations of asthma in asthmatics who are asymptomatic. This illustration is from the ViralZone, one of many free online databases with detailed information about the molecular biology and genetics of viruses. If I was an aspiring Luddite wanting to be provocative about the field of medicine being stuck in the 1950s despite the availability of all of this advanced information - this would be a logical place to start.
In previous posts here I have also critiqued the lack of attention given to environmental approaches to respiratory viruses and the fact that the airborne nature of some of these viruses is not acknowledged - possible because airborne viruses are not contained by hand washing and other direct contact techniques. It s well know that viruses can be collected in the heating and air conditioning systems of public buildings and that altering the humidity and air flow characteristics in those buildings can change the viral concentrations in the air. Whenever I have mentioned this to the administrators of buildings where repeated respiratory epidemics swept through the staff - I got the same response that I received from an airline after I reported a severe respiratory infection after one of their flights: "We are really sorry that you had flu-like symptoms after your flight and look forward to your future comments to help us improve our service."
Time to get serious about respiratory infections and come up with some effective interventions. Effective medication to prevent viral replication and spread in the infected and to create barriers to infection would be ideal and so would environmental methods to reduce the infection rate. Considering the strong incentives in America to work while sick and considering that the average worker is going to get 2 to 3 respiratory infections per year that can last up to 3 weeks in duration means that very few of us and the patients that we treat are not going to be exposed and infected. With the current advanced knowledge of the pathogens and modern heating and air conditioning systems it seems like a lot more could be done right now.
George Dawson, MD, DFAPA
1: Postma MJ. Re: Tamiflu: NNT to prevent a pandemic flu death may be a million. BMJ 2005; 331:1203.
2: Leucht S, Hierl S, Kissling W, Dold M, Davis JM. Putting the efficacy of psychiatric and general medicine medication into perspective: review of meta-analyses. Br J Psychiatry. 2012 Feb;200(2):97-106. doi: 10.1192/bjp.bp.111.096594. Review. PubMed PMID: 22297588.
Graphic at the top of this post is courtesy of: SIB Swiss Institute of Bioinformatics, Philippe Le Mercier, ViralZone. http://viralzone.expasy.org/ licensed via Creative Commons Attribution- NonCommercial 4.0 International License.