Further thoughts on the novel influenza A(H1N1) outbreak

Depending on how you choose to calculate, we are currently approximately two months into the global H1N1 epidemic now. The WHO has put up an interactive map showing the timeline of cases (it is about 2 days behind time), whereas the unknown authors of Wikipedia have depicted this timeline – based on WHO reports – as a graph (it is about 1 day behind time). The figures are sobering – there are now in excess of 12,000 confirmed cases and 90 deaths. That is about 50% more cases than the entire SARS outbreak but slightly less than 12% of the deaths. And there are no signs that the epidemic has peaked yet. The main silver lining (if you choose to see it that way) is that the official figures of infected cases are almost certainly a gross underestimate, so the case fatality rate(CFR) is actually far lower than 0.7%.

There have been several publications on the clinical features of this new influenza, the latest being the WHO weekly epidemiological record (pdf format) on 22nd May 2009. The new disease looks, in essence, like the old influenza, except that a significant proportion of severe and fatal cases have occurred among young and healthy adults. Adults with underlying medical conditions, in particular chronic heart or lung diseases, appear to be more at risk for severe disease. Much has been said about the increased proportion of cases with gastrointestinal (mainly diarrhea and/or vomiting) symptoms, but at 25% or less, this is just a statistic for those looking for a way to make the diagnosis clinically.

The country that appears to be the worst hit outside the WHO North America (comprising USA, Mexico and Canada) region is surprisingly Japan, one of the cleanest countries in the world. Although the first cases were only confirmed on 8th May (imported from either Canada or Detroit, USA where the three cases transited), the figure has jumped to 338 cases as of today – the 4th highest worldwide. It is unclear if the Japanese are just better at detecting and confirming H1N1 cases than most other countries at this point in time, although that would not be unexpected.

Dr Margaret Chan, Director-General of the WHO, has so far resisted (or conceivably also been pressured to avoid) raising the global pandemic alert to Phase 6 – the ultimate level. The problem with the global alert definitions, which is clear on hindsight, is that disease severity (i.e. virulence of the virus) is not included as a factor for up- or downgrading the alerts. This is also the issue for Singapore’s DORSCON-flu alert system, which is largely based on the WHO system anyway. To date, all recorded influenza pandemics have had CFR’s that have exceeded 0.1%, and the H5N1 avian influenza virus – until March 2009 the most likely candidate virus for a pandemic – has an eye-popping CFR of more than 67%. So what do you do when a novel pandemic influenza virus comes along that has a CFR that is not much (if at all) above that of seasonal influenza? You can imagine the quandary facing world experts and health leaders:

• You cannot outright say that the global pandemic alert system (or your country’s alert system) is flawed.

1. But you will still need to somehow tweak the system such that it will be more flexible to deal with viruses of different virulence and transmissibility.

• You cannot tell the different countries to stand down, since it will:

1. Insult the countries (especially Mexico) that have put in great public efforts at tremendous costs to stem the epidemic.
2. Make you look like a fool if history repeats and a more virulent “second wave” follows the first.

• You also do not want to overplay the threat of the pandemic, since it will quickly lead to media and public exhaustion, and you still need to conserve resources for the anticipated “second wave” of the virus.
  

Some have questioned if Singapore – especially its hospitals – has over-reacted in the early phase of the H1N1 epidemic. After all, we swiftly escalated to Orange, created great inconvenience for both healthcare staff and patients/relatives, and doubtlessly used up lots of masks and other protective equipment needlessly. Millions of dollars have been spent and the morbidity cost for patients (in terms of elective operations and clinic follow-ups postponed) has yet to be tabulated. And to date, we have not had a single case of H1N1 in the country. The answer for this writer is naturally, yes. But the benefits of this “over-reaction” have far outweighed its costs, such that this writer feels that it is actually better for us in the long term that we had reacted in this manner.

Singapore has organized several “preparedness” exercises (you can read about a couple of them at this UN website) involving the hospitals in the past. For most of us in the healthcare profession, these have tended to be more farcical than useful – more to reassure the community at large rather than anything else. You almost always knew when (to the hour) and how the simulated patient was going to appear in your hospital. The exercises were also by nature short-lived (it is almost impossible to justify a sustained test of the healthcare system). Thanks to the H1N1 pandemic, we have had a real systems test, highlighting virtually all the issues that had previously been undetected or glossed over (such as sustainability of response). Our responses have previously been based on a SARS-like scenario – all these assumptions have now been challenged and will probably change for a more flexible set of responses. One might argue that all these should have been worked out beforehand, but it is virtually impossible to identify all the fine details and tease out the fault lines in a simulation. “No plans survive first contact with the enemy”, but even “real” anticipated contact has served us well. This does not excuse all the inconveniences and delays/morbidity faced by the patients, but we are far better prepared to deal with any pandemic influenza virus now than before 28th April, and this will surely make a difference when H1N1 or some other virus finally appears in our community.