The Other View on Swine Flu Test and Vaccines

H1N1
Options for India

Dr. J. Gowrishankar              

It was the evening of Saturday 27 June, and I felt the prodromal symptoms of an incipient viral upper respiratory infection ("the common cold") coming on. By Sunday, the infection was fully established with runny nose, sore throat and cough, fever, and the general malaise. On Monday as I am writing this, I wonder, is this the swine flu?

Known in the medical jargon as "swine-origin influenza A (H1N1) virus" (S-OIV), the swine flu agent is a novel variant of the influenza virus to which all of humanity represents a virgin (that is, immunologically susceptible) population. Much like other viruses that cause the common cold, the swine flu agent is transmitted from one individual to another by the aerosol route. Clusters of human infections first occurred a few months ago in Mexico and then in the USA and several West European countries and India have adopted the strategy of screening travellers from these countries in an attempt to prevent its establishment here. Travellers with common cold-like symptoms have been isolated and their contacts quarantined, and subsequent tests have revealed that a proportion (perhaps twenty percent) have indeed been infected with the swine flu.

So then, do I have the swine flu? Neither I, nor any of my close contacts, have travelled abroad in the last six days (which is the maximum incubation period for the virus); but the nature of my job has put me in casual contact with fairly large numbers of unknown people who may have travelled abroad during this period. For example, I travelled by air from Hyderabad to Delhi six days ago and returned by air the next day, and I have also attended several meetings in the past week in closed air-conditioned spaces where senior officials who may likely have travelled abroad were present. Thus, there is a very small, but finite, chance that I have the swine flu.

Which makes me contemplate, is this the way that the swine flu will enter and establish itself in the country? That is, through an unscreened secondary carrier who had but a casual contact with the primary carrier, a traveller returning from abroad? If so, the extensive screening now being undertaken in all the international airports in India would at best serve only to delay, not prevent its spread through the population. The factors which strongly favour such a spread are: that the H1N1 virus is highly infectious (that is, it can easily be transmitted from one person to several others); that person-to-­person transmission can occur during the incubation period (that is, before the transmitting individual is even aware that he or she is infected); that every individual in the population is a susceptible host; and that the clinical features of the infection are no different from those of the common cold. The apparent means to contain its spread and severity is either by vaccination (an approved vaccine is at present not available anywhere in the world), or by treatment with antiviral drugs. The latter course of action is not also practicable in the country, given its expense and the fact that a very small proportion of patients with symptoms of the common cold are likely to be suffering from the swine flu.

It is therefore reassuring to believe that, perhaps, no national strategy of action will be needed even if one could be implemented. It is of course entirely feasible that the swine flu pandemic will progress inexorably around the world, but the fear that it would be as devastating as the influenza pandemic of 1918 may fortunately not hold true. The experience from other countries is that the mortality rate has been quite low, about two for every thousand infected, which is not very different from the rate observed for the seasonal influenza infections (although the age distribution of those suffering severe effects appears to be different, with the swine flu affecting school-age children and adults of working age whereas the seasonal flu has typically affected the very young and the very old). In our country, no deaths have so far been reported amongst those who have tested positive for the virus. In my reckoning, therefore, if we do survive the swine flu scare, it will have been because of the benign nature of the infection, not our national preventive strategy.

Ultimately, however, statistics are for populations, not for the individual. Do I have the swine flu? It is here that I become my own doctor, and my own patient. In keeping with the best traditions of academic medicine, I shall take no antibiotics (since the infection is viral, against which antibiotics are ineffective). The only concession I shall make, for the possibility that it is swine flu, is to take my blood sample now and another two weeks later, so that a retrospective diagnosis of HINI infection can be unequivocally established from the pair of samples by the "method of the rising antibody titre", if that is rendered necessary.

Decisions are never easy in the face of uncertainty, I realize: not for individuals, nor for institutions, nor even for governments and international organizations. Is there likely to be an epidemic in this country, and if so how severe will it be? Is there a need for active interventions? Will a programme of mass vaccination be feasible here, and will the vaccine be safe? (An earlier experience in the USA, in 1976, had been that vaccination against another swine-origin flu virus was associated with a 1:100,000 risk of serious neurological complications).

 The world awaits answers to these and more questions in the months ahead, but I am left to hope that my optimism above is not misplaced.

 

The article above was first published in the last week of June 2009. In the period since, the problem of influenza A (HINI) in India has not gone away; if anything, it has become more stark. As I had then predicted, community transmission of the virus has now occurred in several instances especially within confined population groups such as children in schools, and the health authorities have also scaled down airport surveillance and containment operations. The first few mortalities from infection have been reported from different states in the country. On the face of it, the mortality rate appears to be one percent, but the reliability of this value is unclear given the issue of ascertainment bias, that is, the possibilities that neither all deaths (the numerator), nor more importantly all infections (the denominator), caused by the virus are being correctly recorded. A swine flu vaccine is, under the best of circumstances, still several months away and there have been suggestions that the antiviral chemotherapy may not be very useful especially in children.

Not surprisingly, therefore, there have been reactions of panic (in the sense that these reactions are unlikely to be effective) to the news of spread of the infection, such as closures of schools and offices and even advisories to avoid travel to some cities. In this situation, it is critical for the experts in government and the health sector to maintain balance and perspective in their advice and actions. "Masterly inactivity" was the phrase that was used by one reader of my earlier article to describe my suggestion on the strategy that the country should adopt, and I then remembered that this same phrase has also been employed to characterize the work of the wise obstetrician: to discipline oneself to do nothing in the majority of cases of women in labour, and to possess the skills to judge the few instances when and how one should intervene.

The chickenpox virus is as highly infectious as the influenza A (HINI) virus, and schools and parents do not normally panic when an epidemic of chickenpox occurs. In the case of the swine flu too, much would depend on the mortality rate of infection, and there is reason for optimism (based on experience in other countries) that it would be one-tenth of the one percent rate estimated above.' Masterly inactivity (excepting perhaps for undertaking limited vaccinations, of health services personnel for example) would be the preferred course of action then, along with sound advice (as for chickenpox infections) to isolate patients and quarantine contacts at their homes. On the other hand, were the prophets of doom to be right and the mortality rate much higher, universal vaccination would be the need of the hour, although how it is to be achieved will remain a very big question since even the most optimistic estimates speak of a production capacity of two million vaccine doses for a billion plus-strong population.

Finally, the paired serum samples related to the viral infection which I myself had suffered remain stored in the freezer, awaiting their day of testing to determine whether community spread of the swine flu infection in the country had begun in June itself.

Courtesy:  Biotech News, August, 2009

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