There have been a number of posts on and off about influenza virus, especially the potential of a coming pandemic with a killer virus. This crosses into an area of interest for me, and I have kept up with the literature for some time. Since DemFromCT asked so nicedly I have prepared some informiaton for everyone. I am in the midst of writing a textbook and it just so happens that one section of it focuses on influenza virus. With the publishers permission, I have made the influenza section available on my website. This will hopefully give you a pretty good background on the illness. Go ahead and read it, I'll wait.
Done? Great. If you have any questions, feel free to post a comment and I will do my best to answer them. What follows is my opinions on several topics on influenza.
A possible pandemic
The short answer is, a flu pandemic will most certainly occur, they happen all the time. A quick look at history shows that there were three flu pandemics in the 20th century. As outlined by the CDC they were
1918-19, "Spanish flu," [A (H1N1)], caused the highest number of known flu deaths: more than 500,000 people died in the United States, and 20 million to 50 million people may have died worldwide. Many people died within the first few days after infection and others died of complications soon after. Nearly half of those who died were young, healthy adults.
1957-58, "Asian flu," [A (H2N2)], caused about 70,000 deaths in the United States. First identified in China in late February 1957, the Asian flu spread to the United States by June 1957.
1968-69, "Hong Kong flu," [A (H3N2)], caused approximately 34,000 deaths in the United States. This virus was first detected in Hong Kong in early 1968 and spread to the United States later that year. Type A (H3N2) viruses still circulate today.
Some interesting points to note.
- The most severe pandemic occurred right after World War I. There were many people around the world that were living in poor conditions due to the recent war. This lead to a large population of immunosuppressed individuals -- A great breading ground for illness.
- The number of deaths in the later epidemics were much less and may indicate a trend of decreasing flu mortality. Was the number of deaths decreased because the later viruses were not as virulent? That is certainly possible. Is this a measure of improving medical care? I am sure this has some role. Influenza vaccine was first introduced in 1944 and probably reduced the number of deaths from flu in the Asian and Hong Kong pandemics.
- In each pandemic, the serotype of H and potentially N changes. These new viruses had different antigenic determinants on their surface and thus were able avoid the immune system early in infection, resulting in a more serious illness. Drastic changes in the antigenic properties of these proteins occur when two or more viruses infect the same cell. During assembly and exit from , the 8 separate RNA molecules that make up the influenza genome are packed into the viral capsid. In a multiply-infected cell, the RNA molecules may come from either virus, and new, radically different viral combinations can be made. Most of these mix-and-match viruses will be defective, but rarely it will give rise to a functional virus with a different host range and thus a pandemic. Pigs are great reservoirs for this type of action, since they can be infected by a number of different flu types. Many of the pandemics originate in Asia because farmers live in close proximity to their livestock, allowing the transmission of new strains to the human population. Maybe Moses was right to hate pigs so much.
- Influenza pandemics spread globally in a year, whatever we do once faced with a pandemic, we have about 8 months to react.
Are we ready?
The short answer is, we are getting there, but more could be done, and we won't know if current efforts are going to pay off until the epidemic occurs. The situation in Asia is being monitored by the CDC and others. We will hopefully not be caught off guard and should known early when a pandemic is beginning. Various governments in the developing world are creating plans for how to make vaccine quickly and stock piling doses of antiinfluenza drugs. However, these efforts are only beginning and need to be taken more seriously. In my opinion, an effective prevention strategy will take a significant inflow of cash, and in today's current climate of deficits I just don't see that happening.
Potential courses of action.
Vaccines A vaccine against this strain of influenza would be effective and government agencies are in the process of creating at least test runs of the vaccine. They should be able to make a large number of doses for their populations. Flumist has been found to be very effective and a great way to vaccinate large numbers of people very quickly. This definitely has promise. However, there is no room for error. Contamination problems, as found last year, would be cause very serious delays and los of life.
Drugs The news is more heartening here. A number of drugs have been developed that can mitigate the illness (for example neuraminidase-inhibitors like zanamivir/Relenza and oseltamivir/Tamiflu). The scientist who crystalized neuraminidase, Dr. Graeme Laver, has some interesting thoughts on how to fight the pandemic.
An influenza pandemic will occur at some time in the future: having worked on flu viruses since 1959, I am certain of this. If the deadly H5N1 'bird flu' suddenly acquired human transmissibility, while retaining pathogenicity, the resulting pandemic would cause millions of human deaths. If the pandemic were caused by another bird influenza virus, or if the human H2 virus that disappeared in 1968 were to return, humanity would still be in for a bad time.
No 'pandemic vaccine' could be stockpiled, because of uncertainty about the virus strain. So what can be done? School closure, quarantine, travel restrictions and so on are unlikely to be more effective than a garden hose in a forest fire.
There are, however, two safe antiviral drugs that are effective against all flu viruses, including H5N1. These are the neuraminidase-inhibitors zanamivir/Relenza and oseltamivir/Tamiflu. (Although my crystallization of flu virus neuraminidase led to the development of these drugs and I have a financial interest in Relenza, I have none in Tamiflu.)
Tamiflu is a small carbocyclic molecule that was rationally designed from a knowledge of the X-ray crystal structure of influenza virus neuraminidase. The virus needs neuraminidase to escape from infected cells and spread through the body. The catalytic site of flu neuraminidase, unlike the variable surface antigens, is conserved by all strains of the virus. Tamiflu was designed to fit precisely in the catalytic site of the enzyme, inhibiting its activity.
To be effective, Tamiflu has to be given before infection, or very soon after flu symptoms appear. The time needed to obtain a prescription is a serious drawback.
Although governments around the world are reported to be stockpiling Tamiflu, their strategies for using it are not clear. Britain is reported to have 14.6 million doses of Tamiflu, enough for a quarter of the population. Australia is reported to have enough to protect 200,000 front-line workers prophylactically during a pandemic: two pills a day for 50 days.
This strategy, I believe, is wrong. A more efficient use would be to have Tamiflu available over the counter in local pharmacies, coupled with a rapid, sensitive and accurate flu diagnostic test. People with flu symptoms could then go immediately to the pharmacy, be rapidly tested to see if the infection is influenza and, if it is positive, be given Tamiflu.
Not only would the infection be curtailed -- the person would, on recovery, be immune to reinfection with the same virus.
I believe Dr. Laver is giving very sage advice and if followed, would do much to avert a pandemic in the developed world. Some may fear providing these drugs and tests to the vast unwashed masses, but in the event of a pandemic, that is a risk I am willing to take. My only concern here is that people may try to hoard the drug, as happened with ciprofloxacin during the anthrax scare.
Management of the human population.
This is my greatest concern and has two components.
- Keeping people calm. If a new pandemic begins with a significant mortality rate you can imagine the panic that will ensue in the population. If there is a shortage of doses, which there more than likely will be at least in the beginning, things could get very ugly. How do we decide who gets vaccinated? How do we control those who cannot get the vaccine, because there will most likely be riots if they feel they have no chance of getting vaccinated. Another factor is quarantine. Here I am more optimistic. The SARS epidemic has shown how effective public health systems are getting and this could greatly slow the spread of the illness, giving governments more time to vaccinate and build up does of drugs. However, influenza is more contagious that the SARS virus and it may be more difficult to control its spread.
- The ticking time bomb of overpopulation We have too many people on this planet and over a third live in poverty and are malnourished. This large pool of people with weaker immune systems is just asking for trouble. If we do not start taking steps to slow and reverse population growth, mother nature is going to do it for us. A flu pandemic may be how this occurs, but it could come by way of some other population. One example already occuring is the current AIDS epidemic and it shows no signs of abating.
Two worlds
A second concern is the two worlds that exist. The developing world is going to pay a great price when this pandemic hits, because they will not have the resources to deal with the pandemic, resulting in a tremendous loss of life. The developed world will most likely not help, since they will be maxed out just trying to protect their populations. It would not shock me at all to see millions die and the world population decrease because of a pandemic.
When will it hit
I am going to cop out here and say, I don't know. It really is impossible to predict. I will say we are due, it has been 37 years since the last pandemic.
I hope you found this summary of my view interesting and useful and thanks for reading