There exists a growing body of research showing that homeopathic preparations of disease organisms, such as meningococcal meningitis, leptospirosis and many others are effective in preventing disease. Take a look at this study on the prophylactic effect on Leptospirosis: 'Large-scale application of highly diluted bacteria for Leptospirosis epidemic control' and this more reader-friendly article: 'Homeopathy associated with dramatic reduction in Leptospirosis in Cuban population' published in Medical News Today.
Here is an excerpt:
"In late 2007, in response to a developing epidemic, and with only enough vaccine to treat 15,000 high-risk people, the government decided to treat the entire population of the region, over one year of age, with a homeopathic medicine. This was prepared from the inactivated causative organism by the Cuban National Vaccine Institute.
The homeopathic medicine was given to the 2.3 million population of the provinces usually worst affected. Within a few weeks the number of cases had fallen from the forecast 38 to 4 cases per 100,000 per week, significantly fewer than the historically-based forecast for those weeks of the year.The 8.8 million population of the other provinces did not receive homeopathic treatment and the incidence was as forecast. The effect appeared to be sustained: there was an 84% reduction in infection in the treated region in the following year (2008) when, for the first time, incidence did not correlate with rainfall. In the same period, incidence in the untreated region increased by 22%."
To repeat, this was a government decision.
As far as we know now, homeopathic prophylaxis is not always as effective as the regular vaccines, but very effective nonetheless. In the homeopathic preparations, none of the original pathogens or their products are still present, whereas in conventional vaccines they are, either in a live, weakened or altered form. The homeopathic preparations are also free of formaldehyde, aluminum and antibiotics.
There are many other studies demonstatring homeopathy's effectiveness in the prevention of disease. Fran Sheffield, a well-known homeopath from Australia put together a great reference article, 'Homeoprophylaxis, Human Records and Trials', just click on the link.
It describes the historical use of homeopathy in the prevention of influenza, cholera, polio, scarlett fever, smallpox and diphteria as well as trials of homeoprophylaxix for hepatitis, malaria, meningococcal disease and whooping cough.