by Cynthia Morrow,
MD, MPH
When the virus that causes COVID-19 was first identified in the United States last year, it quickly spread through communities throughout the country because it was a new virus against which we did not have any natural immunity. Simply put, immunity, or our ability to resist a bacteria or virus, occurs when our bodies create antibodies and/or specialized blood cells to fight against these infectious “invaders.” Ending the pandemic will require a significant percentage of people to become immune to the disease.
Herd immunity occurs when a large portion of the population (the herd) is immune to an infectious disease. If enough people are protected, there is some indirect protection for those who do not have immunity, for example, people who cannot get vaccinated because of their age (very young children) or because of an underlying medical condition.
Measles, mumps, polio, and chickenpox are examples of infectious diseases that were once very common but are now rare in the U.S., in part because of herd immunity. There are two ways to achieve herd immunity: when a large portion of the population gets infected with the disease, or when a large portion receives a protective vaccine. Of the two, vaccination is far preferable because it avoids unnecessary illnesses and death associated with the actual disease.
Although we have learned a lot about COVID-19 in the last year, we don’t know the exact percentage of people who need to be vaccinated to reach herd immunity in any given community. Experts don’t believe that there will be a “herd immunity day” that will allow life to immediately go back to normal. And we certainly aren’t at high enough levels yet but every day, more people are choosing to get vaccinated, bringing us closer to our goal.
Although we have not reached herd immunity, as our vaccination rates increase and our COVID-19 case counts decrease, we are making progress. Late last week, the Centers for Disease Control and Prevention (CDC) and Governor Northam announced that fully vaccinated individuals can enjoy taking steps that lead us back to a more normal way of life. For example, fully vaccinated individuals do not need to wear a mask when they are out and about. This is a powerful incentive to get vaccinated!
Unfortunately, while we are making progress, the reality is that this pandemic is a global challenge and we’ll have to see immunization rates rise around the world before we can truly put COVID-19 behind us. It is important to acknowledge that we are likely to continue to experience ups and downs in these unprecedented times but we can all do our part. Getting vaccinated is the single best way out of this pandemic!
