Endemic means that instead of COVID-19 going away forever, it will remain in the community. But when it becomes endemic it means that there are so many people that developed immunity from previous vaccination and/or infection that transmission will be much less frequent. Additionally, when endemic, the virus will not cause nearly as many hospitalizations or death. Once the virus is endemic, it will remain endemic unless a new variant arises that causes more severe disease and/or escapes immunity.
Many respiratory viruses are endemic in our community, including rhinovirus (common cold), RSV (respiratory syncytial virus), and influenza virus. COVID-19 is a coronavirus, and there are many other coronaviruses that that are already endemic and cause the common cold.
At this time, we do not know if there will be seasonal variation with COVID-19 like influenza, RSV, and many other viruses. We predict it will eventually because of the patterns observed with other respiratory viruses. We hope that happens as it will allow us to plan for new seasons and accurately time prevention measures.
Many public health and research laboratories, including ours at Lurie Children’s and Northwestern University, routinely sequence COVID-19 viruses to identify new variants. By doing this worldwide, we can identify new variants and track their movement around the globe. We can also associate new variants with the symptoms and complications they cause, allowing us to identify more harmful variants that cause more severe disease and/or escapes immunity. If a new variant escapes immunity, that could cause a new pandemic of the new variant. This is observed with influenza from time to time. Most influenza viruses are endemic, but occasionally a new influenza virus emerges that humans have not encountered before. Because there is no immunity to that new virus, it can cause a pandemic.
We continue to see new variants emerge in the community. Most recently, BA.2, a cousin to the original BA.1 Omicron variant, has become the most common strain in the Chicago and the US. In other countries, BA.2 was associated with an additional surge in cases and hospitalizations. We have not seen this yet in Chicago but we are watching very closely. To prevent infection, the best thing you can do is keep up to date with vaccines and boosters. Wearing a well-fitted mask, especially when indoors and in crowded places, is also effective for prevention. If having a large gathering, consider performing home COVID-19 tests before hand and do not attend if test is positive and/or you are sick with COVID-19 symptoms.
As of now, we will continue to need to test. Testing will become less necessary once transmission is less and infections are less harmful.