Modelling study suggests pandemic influenza could be controlled at source

[Mingus]

http://www.eurosurveillance.org/ew/2005/050811.asp#4

Modelling study suggests pandemic influenza could be controlled at source

Mary Cooke (mary.cooke@hpa.org.uk) and Jonathan Van-Tam, Respiratory department, Health Protection Agency Centre for Infections, London, United Kingdom

The highly pathogenic avian influenza A (H5N1) virus which is causing influenza outbreaks in South East Asia represents the most plausible candidate for a pandemic human influenza strain since the last influenza pandemic in 1968 [1]. Initial reports of outbreaks in poultry in the region were received in 2003. These were soon followed by sporadic reports of human infection. As yet there have been no confirmed reports of sustained human to human transmission that would signal evolution towards a pandemic.
A keynote paper from a group modelling the course of an influenza pandemic and the impact of control measures has recently been published. The study predicts that, given enough antiviral medication, local cooperation, operational efficiency in implementing measures and a rapid response, a pandemic could be controlled at a potential source in rural South East Asia.

In the study, it was assumed that an infected individual would spread the virus to 1.8 other people (R0 = 1.8) [2]. The impact of a combination of geographically targeted treatment and prophylaxis was modelled (it was assumed that 90% of cases are detected and treated and 90% of persons within a 5 km radius of the pandemic source are prophylaxed). This would require 2-3 million courses of antiviral drugs, as well as social-distancing (such as closing schools and workplaces) and quarantine measures.

The World Heath Organization (WHO) currently has a stockpile of approximately 120 000 antiviral treatment courses resulting from a charitable donation. This study suggests that a significantly larger stockpile is likely to be needed along with considerable liaison and planning between the WHO and the national and local governments likely to be affected.


References:
World Health Organization Communicable Disease Surveillance and Response. Avian Influenza: assessing the pandemic threat. WHO/CDS/2005.29. Geneva: WHO; January 2005. (http://www.who.int/csr/disease/influenza/WHO_CDS_2005_29/en/index.html)
Ferguson NM, Cummings DA, Cauchemez S, Fraser C, Riley S, Meeyai A, et al. Strategies for containing an emerging influenza pandemic in Southeast Asia. Nature 2005 Aug 3; [Epub ahead of print].

 

[stormsailor1981]

Re: Modelling study suggests pandemic influenza could be controlled at source

I Know The Us Sent A Large Stockpile Of Anti-virals Around The 2nd Week In MAY To Be Stockpiled In Asia. Location Was Undisclosed.

 

[Christian Rivers]

Re: Modelling study suggests pandemic influenza could be controlled at source

WHO has since published a plan incorporating these concepts.

WHO (2006). Pandemic influenza draft protocol for rapid response and containment.
May 30, 2006.
http://www.who.int/csr/disease/avian_influenza/guidelines/protocolfinal30_05_06a.pdf

I highlight some key points.
1. Containment is the strategy of early recognition of a pandemic agent and acting to delay pandemic spread (buy time) to allow for effective mitigation such as vaccine production and distribution
2. The emerging pandemic must be detected within the first 20 cases] or 7?21 days;
3. For containment models to work, the reproductive number should be 1.8 or less.
4. The antiviral prophylaxis (oseltamivir,[Tamiflu]) is delivered efficiently to a geographic area (e.g., to an area with a ten kilometer radius) around 90% of clinical cases within two days of symptom onset; and the strain remains susceptible to oseltamivir
5. When containment is successful, total case numbers are also limited to an average of fewer than 150 cases.
6. Most important for us ?
The first successful containment attempt must also trigger accelerated preparations for an uncontained pandemic. It is especially critical to accelerate development, testing, and licensing of vaccines that can be produced in sufficient quantities to immunize whole populations in the event of a pandemic.
References:

Mills CE, R. J., Bergstrom CT, Lipsitch M (2006). "Pandemic Influenza: Risk of Multiple Introductions and the Need to Prepare for Them." PLoS Med 3(6): e135 3(6): e135.

Ferguson, N. M., D. A. T. Cummings, et al. (2005). "Strategies for containing an emerging influenza pandemic in Southeast Asia." advanced online publication.