Last week in an op-ed for the International Herald Tribune, Steven L. Weinreb, M.D., provided an important lesson about vaccines and immunity. He reminds us that when we get vaccinated, we become a barrier to the spread of disease, protecting not only ourselves, but also the people around us. Because of this, Weinreb labels vaccination a “societal responsibility” akin to paying taxes and donating to charity.

Protection for those who cannot protect themselves

Weinreb recently underwent a stem-cell transplant as part of his treatment for chronic lymphocytic leukemia. His own white blood cells were replaced with immature cells incapable of mounting an effective immune response. Like a small infant, Weinreb is at risk of dying from normally innocuous diseases like chickenpox, the measles and the flu. Also like an infant, Weinreb’s immune system is too weak to process many vaccinations. However, as Weinreb points out, vaccines afford some protection to the unvaccinated, as long as a large portion (75-95 percent) of the community receives the vaccine.

The concept, community immunity or herd immunity, is illustrated very well by this animation from the History of Vaccines. The animation illustrates how a vaccinated group can act as a barrier to disease, protecting unvaccinated individuals within the group.

The global impact of community immunity

Here at Sabin, a major part of our mission is to help protect people from preventable diseases who don’t yet have the means to protect themselves. Through our advocacy efforts, we work to make more vaccines available to more people around the world, and with the added protective effects of herd immunity, targeted vaccination programs help to protect groups that can’t be reached by vaccines.

Typhoid vaccines provide a great example of the protective nature of community immunity. The Vi polysaccharide vaccine available to protect against typhoid fever is affordable and proven safe for children 2 years and older. In preparation for increased use of the Vi vaccine, researchers studied the extent of herd immunity in vaccinated communities. They demonstrated the vaccine's effectiveness in the most at-risk group, children aged 2-5, and also found that the vaccine conferred protection to young children who could not be vaccinated. These findings will be used in deliberations about increased use of the Vi vaccine in developing countries.

There are many ways to give back to your community and to help others in need. You can support efforts to vaccinate more children in developing countries. Or simply stay up to date with your own immunizations.