Why was vaccine superior than other methods for conferring resistance to smallpox?
1. Effectiveness: The smallpox vaccine was highly effective in preventing smallpox infection. Studies conducted during the smallpox eradication campaign showed that the vaccine was approximately 95% effective in preventing smallpox in vaccinated individuals. This level of effectiveness was significantly higher compared to other methods of preventing smallpox, such as variolation (inoculation with live smallpox virus) or quarantine measures.
2. Safety: Compared to variolation, the smallpox vaccine was much safer. Variolation carried a significant risk of severe complications and even death, as it involved deliberately infecting individuals with live smallpox virus. In contrast, the smallpox vaccine used a weakened (attenuated) form of the virus or a related vaccinia virus, which posed a minimal risk of serious adverse reactions.
3. Long-lasting immunity: The smallpox vaccine provided long-lasting immunity against smallpox. Studies have demonstrated that immunity from the vaccine could persist for several decades, effectively protecting vaccinated individuals from the disease throughout their lives. This made the vaccine a highly reliable and cost-effective method for controlling smallpox.
4. Cost-effectiveness: The smallpox vaccine was relatively inexpensive to produce and distribute. This allowed for widespread vaccination campaigns, making it feasible to implement mass immunisation programmes on a global scale. The cost-effectiveness of the vaccine contributed significantly to the success of the global smallpox eradication effort.
5. Ease of administration: The smallpox vaccine was simple and straightforward to administer. It could be easily given through a simple skin prick or scratch, allowing for便捷and efficient vaccination campaigns. This simplicity and ease of use were crucial factors in facilitating mass vaccinations and ensuring widespread coverage.
6. Low transmission risk: Unlike variolation, which involved replicating, potentially infectious smallpox virus, the smallpox vaccine did not pose a significant risk of transmitting the virus to unvaccinated individuals. This reduced the likelihood of inadvertent spread of smallpox and facilitated safer vaccination efforts.
The combination of these factors made the smallpox vaccine a superior method for conferring resistance to smallpox compared to other available options. Its high effectiveness, safety, long-lasting immunity, cost-effectiveness, ease of administration, and low transmission risk contributed to its success in eradicating smallpox globally.