The swine flu is a powerful media event, and I will be very surprised if its lethality surpasses the last influenza pandemics. The case-fatality ratio is very similar to the usual flu. It is the same virus (influenza), with a different spreading capability and is possibly less susceptible to the previous flu antibodies that we all carry (there´s the potential danger).

I work on a large managed-care company in Brazil, and have reviewed thoroughly the literature for our response team. The population at risk for complications (need for hospitalization, death) is the same that for the usual flu, small children (<2 y. o.), the elderly (>65 y. o.) and people with chronic heart and lung conditions.

We probably won´t see a pandemic like the Spanish flu of 1918-9, ever. People have better nutritional and hygienic conditions and modern medicine is much better prepared to deal with the complications. I don´t mean antivirals here, save your dollars/euros/… . The evidence on the efficacy of antiviral use on influenza is doubtful to say the least.

Some history for the medical literature fans, from the best medical book on infectious diseases Mandell´s Principles and Practice of Infectious Diseases:

Influenza virus has been causing recurrent epidemics of febrile respiratory disease every 1 to 3 years for at least the past 400 years. Although the disease is not associated with a characteristic manifestation such as rash, the high attack rate, the explosive nature of the epidemic, and the frequency of cough allow the identification of some past epidemics. For example, Sydenham’s account of an epidemic that occurred in 1679 is a clear description of influenza. Hirsch tabulated 299 outbreaks occurring at an average interval of 2.4 years between 1173 and 1875. As discussed later, severe epidemics of worldwide scope occur less often and are referred to as pandemics. The first recorded pandemic that clearly fits the description of influenza occurred in 1580, although others may have occurred earlier. Since then, 31 pandemics have been described. The greatest pandemic in recorded history occurred in 1918–1919 when, during three “waves” of influenza, 21 million deaths were recorded worldwide, among them 549,000 in the United States.

Nigel Davies adds:

I learned a lot about this virus over breakfast this morning — one of my chess team members is a doctor:

1) Although this is a new type of flu, there is little evidence to suggest it's any more deadly than any other kind of flu and in fact it seems rather average. The Mexican deaths have not been duplicated in cases outside of Mexico, which suggests that at some point the data is questionable. One possibility is that the victims may have also had tuberculosis but these questions don't seem to have been asked.

2) A face mask is of questionable value, firstly because this virus is now known not to travel via droplets of water in the breath. Secondly most of the commonly available masks just don't do the job, they're effective for about 30 minutes. A more effective defense is to wash your hands thoroughly, especially before eating.

The way the media have treated this thing is really amazing. I'm already free of television but I'm thinking about how to get free of news altogether. Unfortunately there are some headlines whenever I log into Yahoo to read my email.





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