Relying on Herd Immunity is Not How You Want to Stay Healthy

Should you not vaccinate your children and rely on herd immunity? Many animals live in herds because living in a group makes it harder for predators to kill them. Herd immunity can also help communities withstand infectious diseases, but it comes at a cost. Those “free riders” who want the benefits of herd immunity without using a vaccine make the process of establishing herd immunity more difficult and more lengthy.

What is Herd Immunity?
Herd immunity (or community or population immunity), according to the Cleveland Clinic, means so many people in a group or area have immunity against an infectious agent that it’s tough for the infection to spread or to mutate into something for which few are immune. That immunity occurs because group members survived a past infection, were vaccinated, or acquired antibodies through a passive transfer.

How Does Herd Immunity Develop?
The best way to reach herd immunity is through vaccination. Passive immunity means you obtain antibodies from others. This happens when antibodies are passed to a fetus during pregnancy, to newborns through breast milk, or to a person through blood products with antibodies. Developing immunity after an infection risks severe short and long-term complications and possibly death.

It’s very unlikely herd immunity against COVID-19, for example, would develop without vaccines. It would require far more people to get sick, resulting in many more complications and a significant increase in deaths.

Even with vaccines, achieving herd immunity can be difficult:

  • A part of the population refuses to be vaccinated
  • Some won’t be vaccinated for health reasons
  • Some with compromised immune systems can’t produce antibodies despite being vaccinated
  • It may not be known how long vaccine-related immunity lasts, or it may be highly variable from person to person
  • Vaccines may not be equally available to those in a populatio

Given all these unknowns, simply relying on herd immunity, which may never occur, to stay healthy during an outbreak is not a sensible approach.

What Have We Learned About Herd Immunity?
Vaccines provide effective protection against many deadly diseases. We don’t consider measles fatal, but about 5% of children who get it in areas without good medical care die of it. After a measles vaccine became readily available in the US, cases dropped by more than 99%.

In 2000, measles was declared eliminated in the US in 2000, but there have been outbreaks. Four years ago, 1,282 cases were confirmed in the US, the highest number since 1992. They occurred because unvaccinated people traveled to countries where it was more widespread. When they returned, it passed to others in the US who were also unvaccinated.

Herd immunity is more likely when there are effective vaccinations against diseases caused by one organism (such as smallpox or measles). It’s less likely in cases like the flu, which is caused by many different types of viruses (US flu shots protect against four viruses). Despite its limitations, flu shots prevent deaths and reduce severe complications and hospitalizations.

Did Herd Immunity Work for COVID-19?
Sweden took a different approach to the COVID-19 pandemic compared to most countries, according to Johns Hopkins Medicine. It unofficially tried to achieve herd immunity in 2020 as a national strategy.

Many businesses and organizations remained open without restrictions, including restaurants, elementary and middle schools, public transportation, gyms, malls, and movie theaters. Public gatherings were limited to 50 or fewer people, and they closed high schools, universities, and museums and canceled public sporting events.

Compared to the US, the Swedes enjoyed more freedom of movement and were more able to access businesses, but the cost was high. By the end of May 2020, Sweden had almost 41,000 COVID-19 cases causing more than 4,500 deaths in a population of about 10 million.

Neighboring Norway and Finland combined had less than 600 COVID-19 deaths during that time. The architect of the country’s herd immunity plan, Anders Tegnell, admitted at a June 2020 press conference that “too many people had died too soon” as a result, though he stated they were taking the right approach.

After that initial, deadly COVID-19 wave, Swedes changed their behavior. Their excess mortality was worse than other Scandinavian countries but lower than the rest of Europe, according to Bloomberg. They quarantined when sick, worked from home, kept apart when possible, and most chose the protection of vaccines over herd immunity when they became available.

Do You Have Questions or Concerns About Vaccines?
If so, let’s start the conversation. Call the Bucks County Health Improvement Partnership at 267-291-7882 or complete our online contact form.


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