Pandemic to Endemic—What Does That Mean for COVID-19?

The Sacramento Bee

Nobody knows for sure yet what COVID-19 will throw at us next, but government leaders and pubic health officials are beginning to deliver the news that California residents are stuck with it.

That's why so many have begun using the word "endemic" to describe this respiratory illness. California Gov. Gavin Newsom recently promised that he would share details of the state's endemic plan to address COVID-19.

"Endemic means that we're basically living with the illness," said Dr. Stephen Parodi, an infectious disease specialist and the clinical lead for Kaiser Permanente's coronavirus response. "It also means that it's stable, meaning that the amount of disease we're seeing is not going up significantly or down significantly."

The choices that individual Californians make, Parodi said, will determine whether COVID-19 has a high endemic state in which hospitals are besieged by patients or a low endemic state where there is no need for indoor mask requirements.

The number of cases and deaths have been the most stable among individuals who have chosen to get the COVID-19 vaccinations and booster, Parodi said, while those who are unvaccinated are seeing the greatest risk of infection and death.

In separate interviews, Parodi and epidemiologist Lorena Garcia of the UC Davis School of Medicine stressed that the use of this new term doesn't mean that COVID-19 is any less dangerous or that new variants won't raise the risk of death.

Dr. Dave Chernoff, another infectious disease expert, said: "This virus is very, very capable of rapidly escaping from new therapies that we throw at it. For example, the first two monoclonal antibodies from (Eli) Lilly and from Regeneron, which were introduced during the first wave, have been pulled from the market, because they were designed to neutralize the first virus that came out. They do not work against omicron."

With monoclonal antibodies, researchers essentially copy or clone antibodies that show the greatest power to defeat a disease. It was a costly endeavor, Chernoff said, for a product that was effective for less than 18 months. Still, he said, Lilly and partners GlaxoSmithKline and Vir Biotechnology have introduced new ones.

Danger Not Over

Until 90% of the population gets these immunizations, Parodi said, COVID-19 surges will continue to disrupt schools, hospitals, workplaces and other aspects of daily life.

Over the course of the past two centuries, a number of diseases classified as pandemics and endemics have been rendered less virulent — or virtually wiped out — as a result of vaccination efforts, Chernoff said. He and others pointed to tuberculosis, measles and Spanish influenza as examples.

Right now, however, California remains vulnerable to variants that can defeat current immunizations because viruses are not constrained by borders, Garcia advised.

"There are many countries that are not vaccinated," she said, "and...in California, we have huge interaction with businesses" overseas.

A new variant could even emerge inside U.S. borders, Garcia said, because there are pockets of the state and nation where large numbers of residents have not been vaccinated or boosted, making them a breeding ground for a potential variant.

Consequently, she said, despite changes in government requirements, masks may never be optional for people who have comorbidities or for those who live with them.

The new coronavirus, the pathogen that causes COVID-19, "keeps looking at the human immune response and saying, 'We want to evolve away from it,'" Chernoff said. "That's why we got delta. That's why we got omicron. Preexisting infection did not protect you (from the variants). With influenza, it's different. Pre-existing infection can protect you against severe disease."

Why Is 'Endemic' Being Used Now?

The timing of the state announcement of an endemic plan for COVID-19 is no accident, Parodi said, noting that the success of immunizations in preventing serious illness and death has likely paved the way for it.

"You've got a fairly good-sized amount of the population that has some level of immunity that is vaccine-based, which gives you a broader base immunity against lots of variants," Parodi said. "On top of that, with the omicron surge that we just experienced, a lot of people actually got infected with omicron whether they were vaccinated or unvaccinated. What that means is that an even larger portion of the population has developed some level of immunity naturally based to the latest omicron variant."

As of Tuesday, the state vaccination database showed that 73.9% of vaccine-eligible Californians had received recommended vaccinations and that 55.6% of eligible residents had gotten the vaccines and a booster.

Garcia, an associate professor of epidemiology at the UC Davis School of Medicine, said the nation as a whole needs a pandemic disease unit preparing the country for what's coming, establishing priorities for what will be needed to fight it and setting guidelines for the public and health care organizations.

"We need to talk about what vaccines are, and how they work and how they prepare our body in terms of interaction. It's really about education and preparation for the next epidemic or pandemic," she said.

Parodi said an endemic plan is likely to stress that beating COVID-19 requires the lion's share of state and U.S. residents to get all immunizations.

"For those who haven't gotten their children vaccinated, it's going to be key to getting to an endemic state so that we prevent spread in the schools as we reduce the restrictions (on gathering and masking)," Parodi said.

Testing Is Key

The need for rapid, timely testing also does not go away with endemic diseases, the infectious disease experts say.

All three experts pointed to how drug manufactures, pubic health agencies and physicians depend upon such data to make decisions on things like which vaccine components will be most effective, what alerts they should issue to the public or whether patients require medication.

As part of surveillance testing, public health officials around the nation do what the US Centers for Disease Control & Prevention describe as "ongoing, systematic collection, analysis, and interpretation" of testing samples from the nation's population that help to determine when influenza and other diseases are more prevalent. That information, Parodi said, helps to determine the messages that leaders give to the nation.

Physicians and the general public also need rapid results from diagnostic testing to quickly make decisions on treatment, said Chernoff, who is a consultant to the upstart diagnostics company SummerBio.

"All of these (COVID-19) drugs, whether they're intravenous monoclonal antibodies or they're pills, they must be administered within a couple of days of the onset of the illness," Chernoff said. "After that, they're no longer very useful, so if you cannot get the result back of a test, whether it's a home antigen test or a PCR test in a timely fashion, it really sort of completely blows up the whole idea of treatment."