When Does a Pandemic Become Endemic?

Feb. 28, 2022

As the Omicron wave subsides across the U.S., many states, including New York, have begun to loosen COVID safety measures.  While the virus remains a risk to the unvaccinated and those with underlying medical conditions and compromised immune systems, public health and infectious disease experts are beginning to contemplate what daily life may look like when COVID becomes endemic – meaning the virus takes its place among other circulating respiratory diseases like the flu that, while dangerous to some, does not result in huge spikes in hospitalization and death.

We spoke with Ann Falsey, M.D., a professor of Medicine, Infectious Diseases and co-director of the URMC Vaccine Treatment and Evaluation Unit, on this topic.

When will we know that COVID has shifted from being a pandemic to an endemic?

It’s just not black or white. There's not a line that you can cross and say we are now in an endemic phase. With a respiratory virus, it is very difficult to induce what we call sterilizing immunity that protects you from all infection.  So COVID will not disappear entirely.  I think what people can expect is that it will likely look something like influenza. People who have partial immunity due to vaccination or natural infection will be protected from severe disease.  However, for those at risk – the elderly and people with chronic conditions and compromised immune systems – COVID could continue to be a serious concern.  Keep in mind that the flu kills between 12,000 to 52,000 people in the U.S. every year.

How do we protect those at risk?

It is important to understand that, unlike the beginning of the pandemic two years ago when our toolbox was empty, we now have vaccines/boosters, anti-viral drugs, monoclonal antibodies, and widely-available rapid tests. The hope is that these measures will help create layers of defense that will reduce the harm of future waves and protect the most vulnerable.  There may be future outbreaks that require those at risk for severe infection to take additional steps to be careful and protect themselves, like avoiding crowded indoor settings, frequently washing hands, and even wearing a mask in public. Similar to what would be recommended during a bad flu season.  However, for many people the most important thing they can do to protect themselves is to get vaccinated and, if eligible, boosted.   

What is the likelihood we will need booster shots every year?

The COVID vaccines are a remarkable scientific achievement and are our most important tool against COVID.  While the Delta and Omicron variants were able to produce breakthrough infections in vaccinated individuals, the vaccines still demonstrated strong protection against hospitalization and death, and this protection was increased when boosted.  Because COVID antibody levels decrease over time, the timing and need for booster shots are important questions that the scientific community is trying to answer.  I think it is reasonable to assume that boosters will be recommended if there is a surge in infection or a variant of concern emerges – particularly for those at risk.