Submitted by the Whatcom County Health Department
You’ve probably heard of the term “Herd Immunity.” But what does it mean and how does it work? More importantly, can it be used to fight COVID-19?
How does immunity work?
When germs enter your body, your immune system springs into action. When bacteria and viruses like the one that causes COVID-19 enter your body, your white blood cells make antibodies to fight off the foreign germs.
Once you’ve been exposed to a virus, your body makes memory cells. If you’re exposed to that same virus again, these cells recognize it and tell your immune system to make more antibodies against it.
Herd immunity (or community immunity) occurs when a high percentage of the community is immune to a disease through vaccination and/or prior illness. This makes the spread of the disease from person to person unlikely. Even those who aren’t vaccinated (such as newborns and the immunocompromised) have some protection because the disease doesn’t spread easily within the community.
Why is herd immunity so important?
Many vaccine-preventable diseases that we don’t see much in the United States still make people sick in other countries. It’s possible for travelers to bring these diseases to the United States, where they could then spread. Herd immunity protects us only if enough people are vaccinated.
Will herd immunity work for COVID-19?
The more contagious a virus is, the more people need to be immune for herd immunity to kick in. The virus that causes COVID-19 is so contagious that experts estimate about 70% of people in a community will need to be immune to have herd protection. That’s at least 160,000 Whatcom County residents. That number will be hard to reach without a vaccine or a significant number of people having COVID-19 symptoms.
Also, we don’t yet know if people who have been infected are immune afterwards, or for how long they may be immune. Most people who’ve recovered from COVID-19 do make antibodies against the virus. But so far, it’s unknown whether this will protect them against the virus if they’re exposed to it again.
Relying on herd immunity to lower the spread of COVID-19 before we have a vaccine would mean that a significant number of people would need to become infected, unnecessarily putting many people’s lives at risk. The best way to lower transmission is to stick with the work we’ve been doing, like wearing a face covering, keeping gatherings small and maintaining at least six-feet of physical distance.