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R is the number of secondary cases caused by each infected person; thus R=1.1 means for each ten people sick, one more person will come down with the disease they will transmit it to 11 other people; R=3 means that each infected person transmits it to three others.

To say that the required response to a pandemic depends on its virulence is, of course, like saying rain depends on clouds. However, there have been a number of interesting simulations that do show which measures are effective and which are not at various levels of virulence. I’m using just one group of papers by one set of authors ( Roberts, Baker, Jennings, Sertsou, and Wilson ) to examine this issue so it’s likely that there are other results that might lead to different conclusions. (These papers are also for isolated communities, like New Zealand, that have only a single introduction of the disease so large countries with multiple entry points might respond differently.) Nevertheless, it is interesting to see which measures are effective and which are not.

For a relatively non-virulent strains (i.e. does not rabidly infect others), relatively benign measures would work. Unfortunately, relatively non-virulent strains last longer: the model I’m talking about predicts that if R=1.1, it would take 600 days for the epidemic to run its course if no preventative steps are taken. A very virulent strain, where each sick person infects three others, would burn through the population in 80 days. Closing schools, one of the first thing any parent thinks about, could have a significant social impact if the disease ran that long of a course. On the other hand, it is very effective to simply treat sick people and the people who live in the same house with antiviral meds such as tamiflu. It would also seem that only in the most virulent outbreaks do we need to even quarantine those people in their homes. Which is probably good since that doesn’t seem to have a very high compliance rate (it was assumed in the study that 70% of the people complied with it). Try quarantining some of those folks who refuse to pay their taxes because they don’t believe the constitution gives the government that right!

It really seems that antiviral meds, if effective, are the big difference between now and 1918. However, we don’t need to stockpile enough doses for everyone in the nation, only those sick and those living with them. Mexico City has, both by decree (closing schools and churches) and common consent (avoiding museums etc.), implemented very wide ranging quarantine measures. But do they have antiviral meds? If not, the United States should, out of its own interest, start sharing those meds with Mexico. It would seem that they wouldn’t need very much.

Of course, there are questions about how effective antiviral meds are with a report in the Los Angles Times that Tamiflu is not as effective against N1H1 strains as some older meds. This is another important issue to be settled as soon as possible. (Please note I am NOT suggesting shipping Tamiflu to Mexico as a way of testing its effectiveness. Effective antiviral meds to Mexico is an important public health initiative and not a laboratory study.) If antiviral meds are NOT effective, then public health measures are going to have to have significant social impact for extended periods of time if the virus is more virulent than the R=1.1 case shown here.