Can the Small Pox Vaccine Prevent HIV Infection?

Can the Small Pox Vaccine Prevent HIV Infection?

Recently it was reported by scientists in the journal, BMC Immunology, that decreasing administration of the small pox vaccine is responsible for the exponential growth of HIV/AIDS in the 20th Century.

The historical timing is interesting and the possibility that the Small Pox vaccine could protect against HIV is more than interesting as this could give researchers a quantum leap in understanding how to make an effective HIV vaccine. But do the historical facts make sense?

The small pox vaccine is believed to be the first vaccine, and was even used by the Chinese over four hundred years ago. Small pox killed millions over the centuries and only through vaccination was this very deadly human plague defeated. Only two repositories of the small pox virus, in guarded laboratory conditions, are known to exist in the United States and in Russia. The small pox vaccine is actually composed of a related virus called the cowpox virus, but which provides cross immunity against small pox. While United States servicemen serving abroad are often given the small pox vaccine, mass vaccination has been decided against, despite the risk of small pox being used as a biological weapon.

But could it be possible that one of the first vaccines developed and used successfully also protects against infection with HIV? Small pox vaccination was phased out gradually from the 1950's to the 1970's as it became clear that the disease was being eradicated, the last known reported case of small pox was in Somalia in 1977. HIV and AIDS has increased at an alarming rate since the early 1980's. Blood from people who have been vaccinated against small pox shows an apparently resiliency to the HIV virus. However, as many scientists no doubt will say, just a laboratory test is a long way from proving that the small pox vaccine can prevent either infection with HIV, or suppress the virus to low levels once a person is infected.

Previously to this study, a variety of explanations have been offered for the rapid rise of HIV/AIDS in Africa. Some have included the urbanization of Africa, the destruction of traditional lifestyle patterns by european colonizers, and warfare. The first case of HIV/AIDS, diagnosed retrospectively through the study of blood samples stored in freezers, was in 1959 in what is now the Democratic Republic of the Congo. Using genetic tools, scientists believe that it is possible that the first case of HIV occurred, remarkably, in the 1930's in West Africa. Alternatively, an even earlier date for the first infected human was dated to between 1884 and 1924 by looking at genetic evolutionary changes in the HIV virus. Thus it is entirely possible that HIV/AIDS has been with humankind for over 70 years. Though HIV was determined to be the cause of AIDS in the 20th Century, the HIV/AIDS pandemic has yet to reach its projected full impact. The 21st Century may be defined in large by the world's reaction to, and consequences of, the AIDS pandemic.

But does the small pox vaccine explain why it took so long for HIV/AIDS to "gather steam"? The answer to this question will likely be sought through studies looking at the effects of the small pox vaccine on HIV in people. For example, what is the rate of HIV infection in people who have been vaccinated for small pox? There are so many public health crisis in Africa that it can be easy to see how HIV/AIDS deaths for decades were classified as being due to something else. Indeed, some countries may count a high number of death due to tuberculosis, and not due to HIV/AIDS, even though the combination of tuberculosis and AIDS is deadly and relatively common. That AIDS has so many clinical symptoms, and can manifest itself in a varieties of ways, may have further obscured its identification over the decades in Africa and elsewhere in the world. HIV/AIDS was likely present in the United States for a decade, or longer, until it was first noticed by doctors as a new medical condition.

In addition, while HIV/AIDS now circulates in the general population, as well as in certain high-risk groups, the first cases of HIV/AIDS could have been confined to a small village. Suppose a hunter in West Africa, decades ago, perhaps in 1930 before the Second World War, cut himself while cleaning a recently killed wild chimpanzee. He became infected, but perhaps did not experience serious medical conditions for ten years. Perhaps he passed the virus to his wife, and she passed it to her children. For a decade, or long, the virus might have only existed in this one family. The man may have died and he or his wife may passed the virus on to other only a couple people before they died. Perhaps in the first three decades of HIV's unwelcomed presence in the human population, the virus only existed in a couple hundred people in an isolated village. Such a bottleneck likely occurred, though how the bottleneck lasted may have been due to pure chance. In theory, such a bottleneck could be a reservoir for HIV for a long period of time without the rest of the world realizing that anything was happening.

Only with migration of people, or perhaps work involving long distance travel, did the virus spread out of the country where it first appeared. This might have taken four or more decades as many people in the developing world live close to where they are born the majority of their life. Thus, the urbanization and industrialization of Africa, along with the creation of highways, allowed people and the virus to travel further. Therefore, while the discontinuation of the small pox vaccine occurred around the same time as a boom in the HIV/AIDS pandemic, this may have just been the normal course of how HIV works. If HIV were transmitted much in the same fashion as the annual flu, then the majority of the world would be infected. But because HIV travels between, for the most part, sexual partners, the social network that allowed this to happen was much slower by a couple orders of magnitude.

A variety of causes for HIV/AIDS rapid spread have been proposed, such as polio vaccination and HIV being a CIA conspiracy theory. Most of the more reasonable explanations are proposed as contributing factors, such as increased travel in the end of the 20th Century, increased heroin use in the 1970's, as well as the introduction of blood transfusion techniques and their widespread use in the second half of the 20th Century. Put together, the picture formed is adequate to explain how HIV/AIDS slowly became the global health crisis it is today, and why infection rates soared at the end of the 20th Century and beyond. A variety of cures based on older disease epidemics, such as malaria, have been proposed as a cure for AIDS. And now it seems that the small pox vaccine has been offered as a potential way to prevent HIV/AIDS in the face of mounting failures to produce a viable vaccine. Is this wishful thinking or real science?

Only time will tell.

Written by Mark Riegel, MD

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