More than 30 years ago, the World Health Organization announced that the smallpox virus, a virus that had claimed 300 million lives in the 20th century, had been eradicated by humans, a great victory in the history of human resistance to viruses. Smallpox is also the only virus that has been eradicated by humans. Currently, the last two samples of smallpox virus in the world are kept in the United States and Russia. There was much discussion about destroying these last two samples so that humans would no longer have to worry about smallpox. Finally, in 1996, the World Health Assembly decided to destroy the last samples, but the deadline for destruction was never decided. In 2007, after intense discussions between government officials and scientists, the World Health Organization announced a four-year extension of the deadline for the destruction of the samples, and this year, four years later, on May 24, 2011, after two rounds of consultations at the World Health Assembly, the Assembly decided to postpone the deadline for destruction for another three years, but at the same time reiterated that the deadline would be extended until the relevant research institutions had completed their “necessary” studies. At the same time, the Assembly reiterated that the virus samples must be destroyed after the relevant research institutions have completed the “necessary” studies. So why are scientists and government workers arguing about the date of destruction of the final smallpox virus stockpile? Let’s analyze the reasons for giving the smallpox virus a “death sentence”. How terrible is the smallpox virus? The smallpox virus causes a severe pathogenic reaction and a mortality rate of up to 30% when it infects humans. If a patient is vaccinated within four days of exposure to the virus, he or she can generally resist the virus. There are two main types of smallpox viruses: smallpox major and smallpox minor. When a person is infected with either virus, it causes a similar herpes of skin damage. The large smallpox virus will cause a severe pathogenic reaction and a mortality rate of 30%; however, the small smallpox virus is much less pathogenic and has a mortality rate of only 1%. There are two other very uncommon smallpox viruses that share the common feature of almost complete lethality. After infection by smallpox virus, the incubation period of the virus is usually 12 to 14 days, is clinically asymptomatic, and is not contagious. After the incubation period, there is a sudden onset of flu-like symptoms such as high fever, fatigue, and headache. After two or three days the patient’s fever disappears but is accompanied by the appearance of a rash that begins on the face, hands and forearms and continues to the trunk of the body. The rash also appears on the mucous membranes of the nose and mouth and ruptures rapidly releasing large amounts of smallpox virus. The rash eventually forms pustules and oozes virus-containing fluid, which then softens and crusts over, eventually peeling off to form non-pigmented scars. Patients remain infectious until they are completely cured, but the most infectious period is one week after the rash appears. The virus is transmitted mainly through the air, such as droplets of saliva from person to person, and through contaminated clothing and bed linen, although the latter is less contagious than the former. How can smallpox virus infection be treated? If a patient is vaccinated against smallpox virus within four days of exposure to the virus, he or she can generally resist the virus. And, so far, there is no effective treatment beyond that. Vaccine: the only lifesaver You will not be infected with the smallpox virus for ten years after vaccination, but even after that, the chances of infection and the symptoms of infection are much lighter. Since the vaccine is the only “lifesaver” for people infected with smallpox virus, let’s briefly explain how the vaccine works. Generally speaking, a vaccine is an inactivated or attenuated virus, in other words, a virus against a virus. When inactivated viruses – i.e. vaccines – are injected or inoculated into the body, the body’s immune system quickly recognizes these foreign substances, analyzes them and performs a series of downstream reactions, culminating in the production of antibodies by lymphocytes in the blood to neutralize the virus. When the body successfully produces lymphocytes capable of producing effective antibodies, if the real smallpox virus invades the body, the lymphocytes will recognize the smallpox virus particles more quickly and produce a large number of antibodies to fight the smallpox virus, thus keeping the body safe from the virus. If the body is exposed to smallpox virus without vaccination, or if the body does not have time to produce effective lymphocytes after vaccination, the smallpox virus can escape the immune system and infect the body, causing a series of infection symptoms and even death. Even if death is avoided, the body will be left with scars and to a large extent the virus can cause blindness. It is clear that the most effective means of pre-infection treatment and prevention is vaccination.