Select Committee on Science and Technology Fourth Report


CHAPTER 4: NIP A PANDEMIC IN THE BUD

4.1.  We have already noted that the processes of disease transmission and virus mutation which might lead to an outbreak of pandemic influenza are not adequately understood. At the most basic level it is impossible to predict whether a pandemic strain will be a "pure" avian virus, or a reassortment of human and avian influenza viruses produced in a "mixing vessel" such as a pig.

4.2.  This uncertainty has profound implications for pandemic planning. Reassortment could lead to a "big bang"—a sudden leap in the development of the virus, which could, almost overnight, acquire the capacity to pass efficiently between humans. On this assumption an initial cluster of cases would rapidly expand into a pandemic. Progressive mutation of an avian virus, on the other hand, could result in the virus gradually acquiring the ability to move between humans. Initial clusters, of which there might be several, would be small and slow-growing, as longer chains of human infection developed. Clusters would be harder to spot, but easier to deal with once identified.

4.3.  Recent modelling by Professor Neil Ferguson and others, the results of which were published in Nature on 8 September,[10] shows that once an initial outbreak is identified there is a short period during which a pandemic could be stamped out, by isolation of known cases, restrictions on movement, and intensive, targeted prophylactic use of antiviral drugs. This ground-breaking work has allowed the WHO to establish a rapid response strategy, and as a direct result of this article Roche Products Ltd, manufacturers of oseltamivir (Tamiflu) announced the donation of three million courses of the drug to the WHO to form a rapid response stockpile. In addition, China has announced that in the event of an outbreak it would quarantine the affected area, so providing some prospect that the other prerequisite for success—isolation—could be achieved.

4.4.  However, the modelling appears to be based on the assumption that the outbreak will occur in a rural area; it is far from clear what would happen were it to occur in a major conurbation. Furthermore, even in rural areas the practical difficulties would be enormous. Rapid diagnosis of the initial cluster would be essential—at our seminar Dr Jeremy Farrar even suggested that once the number of cases exceeded 50 it would be too late to prevent a global pandemic. At the same time he painted a vivid picture of the logistical difficulties involved in getting suspected cases from rural villages in Vietnam to properly equipped hospitals where tests could be carried out. Even once a diagnosis is made, antiviral drugs would have to be distributed rapidly to possibly remote and inaccessible locations, which would also have to be sealed off. As Dr Stohr, of the WHO, said, the chances of success are "not huge":

"The models say it can work; the reality would say we have areas in Asia where 80 per cent of the country can only be reached by four-wheeled drive vehicles; where the challenge is to treat in ten to 15 days 80 per cent of a population with a drug which has to be taken over a certain period of time; where you have to have a very high compliance rate; where you have to practically seal off the territory and make sure nobody gets in or out. It is a huge challenge." (Q 210)

Commenting on such issues, Dr Nabarro noted that it might be necessary to draw on "military capability" to implement the rapid response measures. This seems to us to be a sensible and proportionate strategy. (Q 308)

4.5.  A further limitation of the modelling is that is does not take account of the different processes by which a pandemic might emerge: in the words of the Medical Research Council, "It is less clear how effective these strategies would be in the face of a gradual evolution of strains with more efficient human-to-human transmission, and/or diffuse emergence on a widely dispersed geographic front in remote districts with poor communications". There is clearly an urgent need for further work in this area. (p. 138)

4.6.  In the longer term it is clear that the best way to develop a rapid response capability is to invest in improved surveillance and healthcare facilities in the region. The priorities for rapid response were summarised by Dr Stohr: local healthcare workers who are "aware of the clinical science and … attentive"; hospitals within reach of rural communities; regional laboratories able to propagate virus samples and diagnose infection with avian influenza. Much of this investment will thus involve upgrading generic healthcare facilities and skills; it should therefore bring enormous collateral benefits to the region, and the international community, through improving the detection of all infectious disease threats, as well as improving response times to a potential influenza pandemic. (Q 202)

Conclusions

4.7.  Recent modelling by United Kingdom researchers suggests that by rapid diagnosis and targeted response it may be possible to nip a pandemic in the bud. While this research has profound implications, further refinement of the modelling is urgently required, and we look to the Medical Research Council to make this a high priority within its influenza research programme.

4.8.  While it may be theoretically possible to nip a pandemic in the bud, the practical difficulties remain formidable. We welcome the donation by Roche Products Ltd of three million courses of oseltamivir to the WHO, and we also welcome the efforts of the UN and its agencies to improve surveillance and implement a co-ordinated rapid response strategy. We urge the Government to give their full backing to these efforts.

4.9.  We further believe that substantial investment by the international community in improving healthcare in south east Asia represents the best long-term strategy to prevent future influenza pandemics. We recommend that the Government, in collaboration with international partners and the World Bank, make such investment a high priority.


10   Ferguson et al.(2005), Nature 437, pp 209-214. Back


 
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