In the cognitive chart of vaccines, many people are misconvincing the notion that the protection effectiveness of vaccines is lifelong. This misperception, which obscures the correct understanding of the true impact of vaccines, may affect individual disease prevention strategies and public health initiatives.
Indeed, the protection effectiveness of vaccines is not once and for all. After vaccination, the human immune system produces antibody and immunocellal memory for specific pathogens. Over time, however, antibody levels will gradually decline in the body and the activity and number of immunocellular cells will change, a dynamic process that has led to a decline in the protection effectiveness of vaccines. For example, the Hepatitis B vaccine can be maintained at a high level for several years after completion of the whole course of vaccination, but studies suggest that, approximately 10 – 15 years later, hepatitis B surface antibodies in some population groups may be reduced to lower levels or even vasectomy, with a marked reduction in protection against the Hepatitis B virus. At this point, exposure to the hepatitis B virus increases the risk of infection.
With regard to the pertussis vaccine, after childhood vaccination, there is still some protection during adolescence, but in adulthood the effectiveness of protection has been significantly reduced. That is why, in recent years, there has been an increase in the incidence of pertussis among adults in some regions, who were supposed to be immunized for life after being vaccinated, ignoring the time limit of their protection effectiveness and thus becoming vulnerable to infection when their immunity decreases.
For some active vaccines, such as polio, while effective protection can be provided over time after the completion of the basic immunization process, the immune memory will fade over time. The risk of disease transmission increases significantly when wild poison strains or vaccine-derived strain viruses are imported or infested and the immune line previously established for vaccinations is likely to be breached, especially when the number of people with immunization gaps increases.
In addition, the fact that certain vaccines target pathogens themselves in constant variability poses a challenge to their long-term effectiveness. In the case of influenza vaccines, for example, due to the high variability of influenza viruses, the World Health Organization is required to update vaccine strains annually based on globally monitored strains. Even if the influenza vaccine for the current year had been vaccinated before the flu season, the protection received was mainly for the current-season strain and generally only for one influenza season. With the variation of influenza virus strains over the next year, antibodies from previous vaccinations may not be effectively identified and medium and new strains, requiring re-vaccination to gain immunity against new strains.
At the group level, a general misperception by the general public that the effectiveness of vaccine protection is life-long may lead to a decrease in vaccination rates, especially in the strengthening of the immunization or complementary vaccine chain. This would undermine the integrity of the group immunity barrier and provide an opportunity for the re-transmission of infectious diseases among the population, posing a serious threat to public health security. For example, in measles prevention and control, when adults fail to fill measles vaccines in a timely manner because of misperceptions, exposure to imported or locally distributed measles viruses outside the country can not only be a source of infection, but can also be a source of transmission to unvaccinated or failed children and other vulnerable populations, leading to a measles epidemic.
Vaccine protection effectiveness is time-bound and not life-long. Individuals are required to follow professional public health recommendations, in accordance with the characteristics of the different vaccines, their age, health status and risk of infectious diseases in their environment, and to provide, where appropriate, enhanced vaccination or replanting to maintain effective physical protection against specific infectious diseases. At the same time, the public health sector needs to strengthen its vaccine literacy campaign to correct misperceptions about the effectiveness of vaccine protection, to promote the scientific and orderly conduct of vaccinations, and to establish strong lines of defence for mass immunization to safeguard public health and well-being.
