Its creator, Chitose Murai, was not actively involved in cyberbrain sclerosis research at the time, and discovered the vaccine entirely by accident while providing basic care to cyberbrain sclerosis patients. However, prior to the discovery of the vaccine, the most promising treatment for Cyberbrain Sclerosis was micromachine technology, which was anticipated to have numerous ancillary applications. Corporations with investments in micromachine research feared that an alternative treatment would disrupt or even prevent the development of this technology, and secretly applied political pressure to suppress the vaccine.
Ultimately, they were successful: the Murai Vaccine was denied approval by the Japanese government. Of course this was not public knowledge; the government's official explanation for their refusal to approve the drug for public use was that Murai (a general practitioner who lacked the resources or even training to perform complex research and was obviously unable to gain corporate support) was unable to identify the mechanism by which it worked. Murai himself, demoralised and broken, died from the blow of the disapproval.
The development of micromachine technology in search of a cure for cyberbrain sclerosis eventually led to the development of many highly important (not to mention highly profitable) technologies- the Japanese Miracle (a micromachine that can remove radioactive fallout from an area affected by nuclear weapons) and Interceptors (symbiotic micromachines that turn their unwitting hosts into living surveillance devices), just to name two. However at the time in which the series takes place, despite years of research the development of micromachine technology has yet to produce even a mediocre treatment for cyberbrain sclerosis - and cyberbrain sclerosis patients continue to be used as guinea pigs in the development of future micromachine technology.
Later, it is revealed that Hisashi Imakurusu, the man who personally denied approval for the vaccine, was himself in the final stages of the disease. The only reason he continues to live is that he receives the vaccine regularly as part of a top-secret distribution program available only to high-ranking private citizens and public officials. It is a scandal of literally incomparable magnitude: the majority of the populace receiving ineffective treatments to an otherwise terminal disease just so politicians and company executives can develop new technologies, while the only effective treatment is only available to those same politicians and executives.
This is what compelled the Laughing Man to kidnap and threaten Imakurusu. Imakurusu had dedicated his life to finding a cure for cyberbrain sclerosis, only to have the amateur Murai usurp him completely by accident. Although Imakurusu had privately felt that he would have approved the vaccine if Murai had been able to discover why it worked, the Laughing Man believed that the dual motivations of greed and jealousy led him to suppress it. The existence of a custom-crafted 'approval denied' stamp would lead many to agree with him.
The creation and suppression of the fictional Murai Vaccine has its origin in an actual series of events that occurred in Japan in the 1960-70's. The Maruyama Vaccine, also known as Specific Substance Maruyama or SSM(named for its discoverer, Chisato Maruyama), attracted attention as a supposed treatment for cancer. However, the Ministry of Health and Welfare Pharmaceutical Affairs Council refused to approve its use, as its inventor was not an actual cancer researcher. However, the effectiveness of the vaccine is undetermined, as is the existence of a conspiracy to prevent its use.