The Fight Against Influenza

Press, Volume CIV, Issue 30937, 18 December 1965, Page 13

The Fight Against Influenza

DR 4 a':df.rso\ m "B P Shield "! Leeuwenhoek ||||| looked through lens in the seven■Mntli century and saw animals moving IKut in the most demanner” in a sa^va « microand the study of began. |Kt it took another 200 and Pasteur, to demcithe association between kinds of microscopic |Kg particle and disease; a which was hailed as to the causation of disease. for a rime it seemed Mr mi Disease after disease associated with a particubacterium. And it anpearthat in some of these by using the bacto make a vaccine. unity could be conferred oi it the patient suffering of the disease. Howby the beginning of this it became clear that all diseases could b: assowith a particular bacHnm. unfortunate'y was the in such diseases as mumps, chicken pox, cough, poliomye■v and encephalitis, just to Kne a few. It also became Kar that a special infecting Ktenal was the cause. If in■cting material from a pati■t suffering from one <f He.se diseases was passed ■rough a bacterial filter the ■suiting liquid, applied in He appropriate way, caused He disease. The infecting ■ent, whatever it was. could K>s through a filter and so He name “filter passing virus” as applied. Startling Sight later, technological advance roduced the electron microcope. and then for the first me we were able to apprelatc a representation of these articles with our own eyes. Tie results were startling nd even beautiful. Viruses ome in all shapes. Some iave cylindrical coiled nuclei, it hers spherical coiled nucei. Some are simple cubes md others have a compex bitarre structure. The influenza virus, for instance, has a coiled. spherical nucleus with spikes sticking out of the envelope at all angles. Influenza is probably a very old disease, although it seems to have received most of its publicity recently. In medieval times a condition called the “sweating sickness” swept across this country and Europe at intervals and historians. having examined contemporary records, are now fairly certain that this dis-•a.-e was influenza. An early outbreak, which followed the invasion of England by Henry VII and his victory at Bosworth in August 1485. devastated Landon

by mid-September causing a frightening mortality. There are many hundreds of viruses which can infect man, and influenza is that combination of symptoms which is caused by an infection with one of three kinds of influenza virus. The symptoms are usually taken to include headache, cough, sore throat, sweating, musch pains and fever, and it might be thought that with only three different kinds of virus the is relatively simple. However, there are many different strains of each virus, and the virus suffers from another awkward characteristic tn that it is liable to sudden change in its structure. This recurring change takes place at irregular intervals and is responsible for the epidemics and world-wide pandemics of influenza. Pandemic Due In recent times there was the pandemic of 1918-1919. There wa s an epidemic in the late 19205, another in the winter of 1936-1937 and another in the middle 1940 s soon after the end of the war. The most recent pandemic was the “Asian flu” in 1957 and it hardly needs to be mentioned. We all remember it. Experts are agreed that we should be due for another pandemic sometime during the next few years, but whether it will be of the size and nature of the two major ones in the last forty years or so remains to be seen. The important point is that the influenza virus is subject to change, so that infection with

( the 1957 virus does not mean jthat you will be protected I .against the next epidemic,! jnor are the vaccines made! ■from the 1957 epidemic likely I |to be of much use in prevent-! jing the next. Resistance If a vaccine is prepared from a particular strain of one type of influenza virus, and the patient is infected with the same strain, then there is a 75 to 90 per cent chance of resisting the disease. But it has to be infection with a virus against which the patient has been protected. This is a difficult, if not an impossible, task. It has to be emphasised that the vaccine will only protect against one particular virus. It will not protect against all the other viruses, several hundreds of them, which can cause an infection of an influenza-like character. If one wished to avoid being attacked during the next recurrence of influenza, one would have to know how the antigenic structure of the virus is going to change, have the vaccines ready on a scale necessary for mass immunisation, and the immunisation would have to be carried out before the pandemic started. It could be said that a world-wide epidemiological news service might answer the problem. Such a service does exist and did a great deal of very good work during 1957. But by the time it is clear that the disease has changed its nature and is spreading, it is usually too late to take action.

However, there are in any I population, groups of people 'who are at much greater risk ' than others. People who suffer ' unduly from winter infections: i old people; pople with chronic bronchitis; people who already have respiratory infections, such as tuberculosis: people who have recently had an operation. They should obviously be protected. So what of the ordinary person and his ordinary susceptibility to respiratory infection? Is it worth while giving these inoculations, even if they only prevents few people having an attack of influenza during the year? During the last few years many investigations have been conducted into the efficacy of influenza vaccine during those years when influenza is not epidemic. The Medical Research Council did an excellent observation some years ago and several Indus-

trial organisations have repeated this work. In an investigation such as this, man is by far the best animal. Laboratory animals can be used, but their reactions to viruses are rather different from those of man. Further, opinion enters so much into man’s assessment of ordinary conditions that when he is being used as a laboratory animal, it is essential that he should be unaware of what is happening.

Successful Trial To achieve this end the “double blind” trial has been used with great success over the last twenty years or more. It consists of arranging matters so that neither the observer nor the observed knows whether any particular individual has received the material under investigation or an inert control material.

Everyone is injected with a substance which looks the same, be it active or inert, and in the analysis of the results it is not known which individuals received which. 1000 Volunteers In B.P.’s London office and at Sunbury during the winters of 1963-64 and 196445, about 1000 people each winter agreed to take part in a double blind trial into the efficacy of influenza vaccine. On each occasion one third of this number received the control substance only, and the whole group’s experience of influenza was analysed the following summer. For those who have access to journals, the results of the first winter have been published in the British Journal of Industrial Medicine, Volume 22, No. 3, page 217, by Dr. P. B. Cook. The results of the second year's investigation have been analysed by Dr. B. W. Duck, and it is hoped to publish them later. But it is possible to state quite categorically that the vaccine afforded no protection in either winter season, those who received the control substance suffering the same amount and the same kind of upper respiratory infection as did those who received the vaccine. We also know that during those winters the incidence of influenza was ordinary. Still Defiant This experience of ours accords very well with the experience of the Medical Research Council and other observers that influenza vaccine gives no protection during a non-epidemic year. We do not propose therefore to offer this protection in future years, except to those people who have an unusual susceptibility during an ordinary winter. That such people exist I have already mentioned, and we are prepared to do everything we can to help them get through a winter with the minimum trouble. Let me emphasise that we are talking about influenza and not the common cold. The common cold still defies prevention but when this is achieved it will indeed be a major advance.