More Flu Cases in Singapore

The first case of novel influenza A(H1N1) virus infection to be identified in Singapore arrived in the early hours of 26^th May. The SMU student had flown in from New York, slipped past the thermal scanners although she had already developed symptoms onboard the flight, but sought medical attention in the later part of the morning. An alert general practitioner had her transferred to the Communicable Diseases Center (CDC), where laboratory testing confirmed that she was infected with the novel influenza virus in the early hours of 27^th May.

Within 36 hours, we have three further cases unrelated to the first, all of whom have come from different parts of the United States. All four patients are being treated at CDC, with none reported as having serious infections. In other words, they would not ordinarily have been hospitalized, except for the unfortunate circumstance of being infected with this new influenza virus. It is understood that their close contacts are also being quarantined (albeit not in the hospital), and have been provided (likely) oseltamivir prophylaxis to prevent the development of overt disease.

On the backdrop of a pandemic with confirmed cases in 58 countries, the importation of this number of cases is not unusual. There will likely be more in the coming weeks. What is unusual is the length of time it had taken for the first case to appear on our shores, given the recent identification of cases in surrounding countries, and Changi Airport’s status as a major aviation hub for the region.

An analysis of the news reports suggests that our Ministry of Health (MOH) is trying to contain the spread of disease at this point. By giving antiviral prophylaxis to all contacts of the initial cases, it is hoped that they will not develop the disease and transmit it to others. One might ask, given the mild nature of this influenza to date – could these contacts not just have been quarantined, rather than risk the additional potential adverse effects of oseltamivir? These are relatively rare, but some – especially the controversial neuropsychiatric effects (fiercely contested by Roche investigators, with a nebulous warning by the FDA) – are nontrivial. The experts at MOH must have performed their calculations and either projected that quarantine alone would be insufficient for containment, or that the benefits of antiviral prophylaxis outweighed the risks/costs.

Some – including the National Neuroscience Institute director – have argued that containment is ultimately futile, and that we should allow the first wave of the virus to run its course in Singapore to develop herd immunity. This strategy is based in particular on the 1918-1999 pandemic, where the first wave was relatively mild (albeit with higher mortality than seasonal flu), whereas a more virulent mutated form returned 4 months later. Survivors of the first wave were not infected by the far more deadly ‘second wave’ virus. This strategy was rebutted by MOH’s Director of Medical Services, who was opposed to subjecting the population to unnecessary and unknown risks.

Will there be a ‘second wave’ and will it be more deadly than the first? The answer to the first question is ‘probably – and there might well be more than two waves’, while the second question is harder to answer with any degree of confidence. Dr Mark Miller and his colleagues from the Fogarty International Center of the National Institutes of Health, USA, wrote a concise and informative article on previous influenza pandemics that is well worth a read. The short summary of most experts’ viewpoints seems to be this: there is a lot of knowledge on historical 20^th century influenza pandemics but we still have no idea how this one is going to play out because each pandemic had been different in significant ways. Sometimes a little extra knowledge (and therefore the knowledge that little is certain) can be paralyzing. Sobering to consider 2-5 years of elevated DORSCON-Flu alerts though.

Will we be able to stop the virus from entering and transmitting in the local community? Probably not in the long run, although even a delay – as well as attempts at diminishing transmission with social interventions should community spread occur – will be beneficial. There might (or might not) be a widely available vaccine in the next year. There might (or might not) be a more virulent ‘second wave’ influenza virus. But whereas our medical services are generally first-rate, the current undersupply is unlikely to be alleviated in the next couple of years. An increased utilization (or reduction) of health services because of influenza in the short term may lead to critical compromises that we can ill afford.