For hundreds of years, people have been using inoculation – the introduction of a small amount of weakened virus into a healthy body – to prevent the spread of illness in a community. The healthy body builds defenses against the introduced illness and fights it off.
The practice was brought to England from Turkey in the 1700s. It has led to the development of vaccines, one of the most powerful lifesaving tools against disease in the world. When enough members of a community are vaccinated against a disease, they are not only protected as individuals, but they also create herd immunity.
What Is Herd Immunity?
Imagine a community as a herd of animals. Herd immunity, also referred to as community immunity, is like a shield protecting the entire herd from an infectious disease. When a large portion of the community becomes immune, it strengthens the shield, making it difficult for the infection to spread from person to person.
This indirect protection benefits everyone, including those who are unable to get vaccinated due to medical reasons.
Why Is Herd Immunity Important?
Herd immunity is crucial because it safeguards vulnerable groups like infants, people undergoing cancer treatment, or those with weakened immune systems. These individuals might not be able to build a strong enough immune response through vaccination or prior infection.
Herd immunity creates a protective barrier around them by limiting the spread of the disease in the community.
How Is Herd Immunity Developed in a Population?
Herd immunity has been around for a long time, but humans have found ways to vastly improve it.
Natural Infection Immunity
When people get sick and recover from a contagious disease, their bodies develop natural defenses against future infection. This immunity comes at a cost, though, as the initial infection itself can cause illness and potentially serious complications, as well as allow the disease to spread to others who are exposed to the illness.
Vaccine-Induced Immunity
Vaccination is a safe and effective way to achieve herd immunity. Vaccines introduce a weakened or inactive form of a virus or bacteria, training the body's immune system to recognize and fight the real threat without causing illness. This creates immunity without the risks associated with natural infection.
Achieving Herd Immunity Through Vaccinations
Vaccination programs play a critical role in establishing herd immunity. When a high percentage of the population gets vaccinated against the flu, for example, we significantly reduce the number of people who can harbor and transmit the disease. This creates a wall of protection for the entire community.
While some people may have health conditions that prevent them from getting vaccinated, vaccines are well-tested and safe for the majority of the population. From a very early age, children going to their regular pediatric visits get a series of immunizations that protect against childhood diseases.
Adults can take advantage of annual flu shot opportunities, protecting themselves and those around them against a common infection that kills tens of thousands of Americans every year.
New vaccines may be developed that can protect us against other diseases, and boosters may be recommended in some cases. Most people can contribute to the strength of the shield that is community immunity.
Is it Possible to Achieve Herd Immunity Without a Vaccine?
While herd immunity can develop through natural infections, it's not a recommended strategy. Widespread infections can lead to unnecessary illness, strain health care systems and result in preventable deaths.
Vaccination is a much safer and more efficient way to achieve herd immunity and protect everyone in the community.
Vaccinations at University Health
Protect your community and stay up to date on your vaccines. University Health pharmacies offer vaccines such as the flu and COVID-19 vaccines. Ask your primary care provider about which vaccines you might need.
