Pandemic flu - how to protect the world

We urgently need a vaccine, and meanwhile must rely on keeping people apart. Research on the social challenge to developing countries could be "very important"

SUMMARY
WHO's Assistant Director-General for Communicable Diseases, David Heymann, speaking to RealHealthNews in early April, outlines the challenges - both technical and political - facing the world in protecting us from the next influenza pandemic.

(May 07)

RHN: You’re working on faster ways of creating the vaccine, once the virus is identified aren’t you?

David Heymann, Assistant Director-General for Communicable Diseases, WHO: That’s correct – there’s a Global Pandemic Influenza Action Plan [see READ ON, below] to increase vaccine supply, in two parts. The first is to increase the use of seasonal vaccine over the long term – and by doing that we’ll increase the general production capacity of vaccine; and the second is to promote R&D for new vaccines.

RHN: Of course you are faced with a terribly difficult challenge, because you don’t know exactly what form the pandemic flu virus will take – there’s no guarantee it will be H5N1.

DH: Absolutely, and we don’t even know if there’s going to be a pandemic.

RHN: But you can be sure there will be one sometime, can’t you?

DH: That’s correct. That’s why it’s important in the long term to increase production capacity, and to do the research that would permit a more rapid production of vaccines. Today, it takes six months from the time the decision is made, because it’s a complex process of growing the virus in chick embryos, and further processes after that. So all that time might be cut with a different production methodology.

The ultimate goal would be to develop a polyvalent vaccine – one that would be effective against all strains that could threaten a global pandemic. We could do that provided there were conserved regions in the viruses [constant regions of the virus genome, creating constant regions of the virus to which the vaccine could create immunity].

RHN: What kind of production methods are being developed?

DH: Right now there is production in eggs. Cell-based production is also under development, but those vaccines are not yet licensed.

RHN: One major obstacle is that we don’t understand, do we, exactly what makes an influenza virus “pandemic”. We don't know the specific characteristics a virus must have to make an influenza virus both virulent and highly transmissible.

DH: That’s right. All we know are the two hypothesised mechanisms, that it happens by recombination [between human and bird or animal viruses] and/or an adaptive mutation in the human host, but not enough is known about what specific recombinations and mutations would need to occur.

RHN: There was an interesting study by recently in ferrets [the animal model for human flu] by Terence Tumpey et al. that showed that if you took the 1918 “Spanish flu” epidemic virus, that killed so many millions, and changed just two amino acids in its coat, that it would bind to the lower lung rather than the upper part, and so not be coughed out – stopping transmission and becoming benign. [See READ ON].

So the conclusion is that only a tiny change in the virus can makes the difference between a disaster, and no problem at all.

DH: That’s right, and it’s not really known what the causes are, which makes the problem for creating influenza vaccines.

RHN: Is enough research taking place on this, do you think?

DH: Certainly one of the most important things is the sharing of every virus in an infection, and you know we ran into a glitch on that recently with some countries not being willing to share viruses freely. [David Heymann refers here to Indonesia – see READ ON.] We are working very hard to overcome those issues.

We’re very grateful, in fact, that Indonesia did call our attention to the fact that there is a need to develop new methods of sharing the benefits of sharing the viruses. And we’ll be working on that, to try to get stockpiles in place…

RHN: I understand that Indonesia was concerned that it wasn’t getting value from the virus samples it was giving.

DH: Yes, and we’re grateful to Indonesia for having vocalised this…. For example they want more transfer of technology.

RHN: Has any other country begun to follow Indonesia’s lead on this?

DH: Not as of yet. We have a resolution on virus sharing to pass through the World Health Assembly that will bring out a great discussion.

I think that developing countries have recently also become acutely aware of the need to develop [influenza vaccine] production capacity in their own countries. We know that maximum present production capacity for a monovalent vaccine is 1.5 billion doses. That’s nothing compared to the world population.

RHN: And there are three billion people in urban slums, which means no clean water, sanitation or easy access to health care.

DH: In slum areas as everywhere else, the answer is social distancing – finding places to go to keep apart. In Hong Kong in the SARS epidemic, when they had an outbreak in an apartment building, they were able to move all those people to areas where they’d be relatively safe.

… it means in those areas where people congregate, trying to help them not congregate, to help them to understand that it’s risky to meet in social gatherings and so on. But it’s a very difficult issue while there is not enough vaccine supply. There’ll be a lag, should there be a pandemic, as the virus is identified and the vaccine made. In the meantime we’ll use H5N1 vaccine, if the pandemic is caused by a variant of H5N1 – and maybe that will have an effect.

RHN: There were studies in Nature and Science a year or so ago which modelled the containment of a pandemic H5N1 outbreak in a rural area, using antivirals and social distancing. But it did seem to imply a fairly well-organized and well-off country, and an area with a relatively low population density. RealHealthNews is concerned that if a pandemic flu virus gets into one of the poorer countries, and into their urban slums, this social distancing or containment model just won’t work.

DH: It will be very difficult, that’s for sure. Hopefully there will be stockpiles of vaccine, and antivirals, to use together for containment. But the fact is that in contingency planning there have to plans for people to keep apart or to be moved.

RHN: In some of the more authoritarian states won’t they simply put the army around their own slums?

DH: That may very well be, and not just in authoritarian states. You can’t predict what will happen.

RHN: Is anyone doing social modelling of what would happen in these circumstances?

DH: In the slum areas? Not that I know of.

RHN: Do you think it’s worth doing?

DH: I think it might be very important.

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