O469 - Advances in Vaccine Therapy

This isn't a full post, but I really liked this quote (whole section, really) from a review written by Alexander Fleming (who you'll recall is credited with discovering penicillin, not that it's particularly relevant here).

"The question whether or not an individual can be protected against epidemic influenza by means of a vaccine is one which is of the greatest importance in medical practice. This question leads to another, What is epidemic influenza? Before the great war we were quite content to think that it was infection by the influenza bacillus of Pfeiffer, and there is no doubt that in the 1918-19 pandemic this bacillus was present in practically 100 per cent of cases in England and France, and that it was responsible for much of the mortality. However, more recent work, especially at the Medical Research Council laboratires, has definitely established that the primary infective agent in epidemic influenza is a virus. This virus can be passed on in ferrets and mice, and can be cultivated in the incubator in chicken embryos still in the shell. It appears likely that mild influenza, such as the first wave of 1918 or the more recent epidemics, is to all intents and purposes a pure infection of the virus and that the serious and deadly epidemic of 1918-19 was due to a combination of this virus with a bacterium, especially the influenza bacillus.

"A very interesting influenza story comes from America. During and following the 1918 pandemic an epidemic of swine influenza appeared among the pigs in that country. This swine influenza is a serious and fatal disease, and has been investigated by Shope (1937) [054] more thoroughly than was possible in any human disease. Shope discovered that swine influenza was due to a combined infection with a virus and a bacillus practically identical with the influenza bacillus of Pfeiffer. If he infected pigs with a pure virus without the bacillus a transient fever resulted and all the pigs recovered; if he infected them with the bacillus alone practically nothing happened; but if he infected pigs with both the virus and the bacillus typical swine influenza resulted and the pigs died with pneumonia. Shope found that the pigs which had been given the pure virus and had recovered from the trifling infection that resulted were completely immune to fresh infection with the virus. He also found that inoculation of the pigs with vaccines made from the influenza bacillus gave some degree of protection against swine influenza, although it was not so complete as the protection with the virus.

"Here it will be seen that all the animals receiving the vaccine of the influenza bacillus suffered from a much milder disease than the controls, which had not been protected. This observation is of the greatest interest in view of the attempts made to prevent influenza in man with bacterial vaccines, especially those of the influenza bacillus. After the 1918 pandemic many papers appeared stating that such vaccines had conferred a degree of protection against influenza, but none of the figures given have satisfied statisticians. In view, however, of Shope's experimental results with pigs it appears that these claims were justified and that protection can be obtained by such bacterial vaccines.

"Attempts are at present being made to protect man against influenza by means of a vaccine of the influenza virus. The results on experimental animals have been successful, but the opportunity has not yet arisen for the final proof that it can protect man during an epidemic. It seems likely that in the near future it will be possible to obtain a virus vaccine which will give, either alone or in combination with the older bacterial vaccine, complete protection against epidemic influenza in the majority of the inoculated individuals."

Citation: Fleming, A. Advances in Vaccine Therapy. Br Med J 2, 99–104 (1939).