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What does "R of 1·1" and C mean here?

 
 
Reply Sun 10 Nov, 2013 01:41 am


Context:

Moreover, hundreds of thousands of people are fleeing Syria and seek refuge in neighbouring countries and Europe. Because only one in 200 unvaccinated individuals infected with WPV1 will develop acute flaccid paralysis (case/infection ratio C=0·005), infected individuals can spread the virus unrecognised.4, 5 Inactivated polio vaccine, which is used throughout Europe, only partly prevents vaccinees from infection, but it reduces transmission and is highly effective in prevention of acute flaccid paralysis,4 and thus further reduces the ratio of acute flaccid paralysis to infection. In regions with low vaccination coverage (eg, Bosnia and Herzegovina [87%] or Ukraine [74%]), particularly those with low coverage of inactivated polio vaccine (eg, Austria [83%]),1 herd immunity might be insufficient to prevent sustained transmission.
Assuming a borderline effective reproduction number R of 1·1, we expect to see C(Rn+1—1)/(R—1) cases of acute flaccid paralysis within n transmission generations. It might take more than 30 generations of 10 days5—nearly 1 year of silent transmission—before one acute flaccid paralysis case is identified and an outbreak is detected, although hundreds of individuals would carry the infection. Vaccinating only Syrian refugees—as has been recommended by the European Centre for Disease Prevention and Control6—must be judged as insufficient; more comprehensive measures should be taken into consideration. Oral polio vaccination provides high protection against acquisition and spreading of the infection, but this vaccine was discontinued in Europe because of rare cases of vaccination-related acute flaccid paralysis. Only some of the European Union member states still allow its use and none has a stockpile of oral polio vaccines.2 Routine screening of sewage for poliovirus has not been done in most European countries,2 but this intensified surveillance measure should be considered for settlements with large numbers of Syrian refugees.

More:
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(13)62220-5/fulltext
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View best answer, chosen by oristarA
contrex
 
  1  
Reply Sun 10 Nov, 2013 02:27 am
The effective reproduction number is called R in this illustration. C is case/infection ratio. You must read the rest of the article to discover what Rn stands for.


oristarA
 
  1  
Reply Sun 10 Nov, 2013 05:58 am
@contrex,
contrex wrote:

The effective reproduction number is called R in this illustration. C is case/infection ratio. You must read the rest of the article to discover what Rn stands for.





Thank you Contrex.
One of the most important question: what is 1·1? It looks not like 1.1.
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contrex
  Selected Answer
 
  2  
Reply Sun 10 Nov, 2013 06:25 am
I suspect it the raised dot is a typographical error. I cannot read the original article (your link is broken) but other epidemiological texts use ordinary decimal points for R.

E.g. http://www.ganfyd.org/index.php?title=Reproduction_number

Quote:
Effective reproductive number (R) is the actual average number of secondary cases per primary case observed in a population with an infective disease. The value of R is typically smaller than the value of basic reproductive rate(R0), and it reflects the impact of control measures and depletion of susceptible persons by the infection.

Examples

Early in an new infectious disease R will be close to R0

SARS
R0=3.6 (95% CI 3.1-4.2) which was the same as R in early stages as this condition had no specific treatment[2]
R=0.7 (95% CI: 0.7-0.8) obtained by intense control measures and allowed fairly rapid control once recognised as a highly infectious disease with respiratory transmission
Swine influenza 2009
R0 northern hemisphere summer 1.4 – 1.5 with delay strategy
Initial R from southern hemisphere winter 1.8 to 2.3 in community/school winter outbreaks before disease recognised and control measures emplaced[3]
oristarA
 
  1  
Reply Sun 10 Nov, 2013 08:14 pm
@contrex,
contrex wrote:

I suspect it the raised dot is a typographical error. I cannot read the original article (your link is broken) but other epidemiological texts use ordinary decimal points for R.

E.g. http://www.ganfyd.org/index.php?title=Reproduction_number


That's informative.

Directly copy he link for the context and post it into your browser's address box.





contrex
 
  1  
Reply Mon 11 Nov, 2013 02:12 am
@oristarA,
Quote:


Directly copy he link for the context and post it into your browser's address box.

Of course I did that. Do you think I am a fool? "Article not found"
oristarA
 
  1  
Reply Mon 11 Nov, 2013 06:47 am
@contrex,
contrex wrote:

Quote:


Directly copy he link for the context and post it into your browser's address box.

Of course I did that. Do you think I am a fool? "Article not found"


Eh? I tried it again. It is normal here:

http://i43.tinypic.com/xpqwzm.jpg
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