How Vaccines Protect You and Your Loved Ones

Vaccines have saved more than 150 million lives over the past 50 years — an incredible six lives every minute. They have had an outsized impact at a relatively low cost. Yet, the current rise in measles outbreaks and polio surges shows that challenges like vaccine hesitancy and limited access are leaving more people defenseless. Here’s how vaccines work and why they remain a critical tool to protect your loved ones from dangerous diseases.

How vaccines work

The immune system protects us by recognizing harmful invaders like bacteria or viruses, called pathogens. It identifies these pathogens by unique markers on their surface, called antigens. When the immune system encounters a new antigen, it creates special proteins called antibodies that attach to the pathogen, marking it for destruction by specialized immune cells that can eat the tagged pathogen. Other powerful immune cells called T-cells help ensure that the best possible antibodies are produced and in certain cases can also result in direct killing of your bodies own cells if they have been infected, that is, if the pathogen resides inside your cells. These combined mechanisms are an incredibly powerful and specific way to clear unwanted viruses and bacteria before they expand to harmful levels. There are other cell types involved and a comprehensive scope is beyond our discussion here, but see this Centers for Disease Control and Prevention (CDC) explainer for an overview.

The immune system also “remembers” these invaders by storing memory cells, which can quickly respond if the same pathogen appears again, often preventing illness. These are called memory B and T cells and they can persist in the body for many years, providing lifelong protection against reinfection.

Some vaccines work by introducing weakened or inactivated forms of disease agents, forms that can train the immune system to respond, but are not capable of replicating or causing disease. In some cases, vaccines may not completely stop the disease but can make it much less severe.

How vaccines protect our loved ones

Vaccines are seen the world over as a best buy in public health because they have had outsized impact/effectiveness for the cost.

  • Children/Elderly: The immune system is most effective during early and mid-adulthood. During childhood and later in later in life, immunization bolsters immune reaction to prevalent diseases, including pneumonia and flu.
  • Newborns: Mothers pass antibodies to their newborns during pregnancy and breastfeeding, and vaccines received during pregnancy can protect newborns before they are able to have their own vaccinations.
  • Vulnerable populations: With certain caveats, vaccines help those with chronic conditions such as HIV or diabetes who have more difficulty mounting an immune response to diseases. The applicability and benefit of vaccines in these populations can depend on the baseline T and B cell levels.
  • Communities experiencing outbreaks: When a disease is prevalent in a community, such as cholera, measles or meningitis, vaccines help protect the population and may bring a faster end to an outbreak.
  • Travelers: Some diseases, such as yellow fever or cholera, may appear in different countries, and travelers may require protection.
How vaccines protect through herd immunity

Diseases can spread rapidly, affecting many people in a short time and sometimes leading to outbreaks. Vaccination helps stop this by making it harder for germs to move from one person to another, protecting the whole community. This principle is sometimes called herd immunity.

This protection also extends to those who can’t get vaccinated, as the disease has fewer chances to spread. And if someone does get sick, outbreaks are less likely because the germs can’t travel easily. Over time, this can make the disease rare — and sometimes, it can even disappear completely.

 

How vaccines help stop antimicrobial resistance

Some life-threatening infections, like tuberculosis, no longer respond to many first-line drugs due to their overuse and misuse. Antimicrobial resistance (AMR) occurs when bacteria, viruses, fungi, and parasites become resistant to medicines, making infections harder to treat and increasing the risk of severe illness and death. Vaccines are a powerful tool against AMR, as they prevent infections, reduce the need for antimicrobials, and limit the spread of drug-resistant pathogens.

Why vaccines can be better than natural immunity

Vaccination protects most people before disease strikes, while natural immunity develops only after someone becomes ill. With vaccination, individuals avoid possible death or disability from serious illnesses.

How the benefits of vaccines outweigh their risks

Vaccines are rigorously tested and monitored to ensure their safety. Like any medical intervention, vaccines can have side effects, but these are typically mild and temporary. Decades of research and real-world evidence consistently show that the benefits of vaccination far outweigh the risks, preventing an estimated 4 million childhood deaths worldwide every year. It is estimated a further 1.5 million lives could be saved annually with better global vaccine coverage.  Vaccines are one of the most effective tools in medicine, saving more lives than any other health intervention, including antibiotics.