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COVID-19: What it means to move from pandemic to endemic

Stanford epidemiologist says that COVID-19, in some form, is likely to persist

People walk around the farmers market at the Caltrain station in Mountain View on July 18, 2021. Photo by Magali Gauthier.

The number of COVID-19 cases in California is steadily declining. Mask mandates are being peeled back. And Gov. Gavin Newsom recently unveiled "California SMARTER," a plan outlining a future of public health support during the next COVID-19 phase.

So what will "endemic" rather than "pandemic" COVID-19 look like? That depends on many variables, according to Stanford epidemiologist Dr. Yvonne Maldonado. Much of what will occur depends on what the virus itself will do.

At the moment, we're still in a pandemic phase of the health crisis, said Maldonado, a professor of pediatric infectious diseases and of health research and policy at Stanford.

"For now, we're in a period of declining cases and of increased immunity and there's no other variant of concern in sight" in California, she said. But "we could be heading into an endemic phase or be in the early stages."

The new subvariant of omicron — subvariant BA.2, which is 33% more transmissible than its predecessor — is present in the Bay Area, according to local health administrators, but Maldonado said thus far it hasn't spread widely and there isn't a huge spike in cases. If that metric holds and the number of cases, whether high or low, doesn't spike, then we'll likely be in an endemic phase of the disease.

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Endemic doesn't mean the disease is disappearing from within a population. It simply means that the disease is widely circulating with a more or less constant level of cases that don't fluctuate wildly. Rather than fading away, COVID-19 will likely be something we'll continue to live with.

Dr. Yvonne Maldonado. Courtesy Stanford Health Care.

In general, diseases can be endemic to populations in some parts of the world but not others. Cholera is present and endemic in some countries but isn't prevalent in the U.S., for example. Tuberculosis is also an endemic disease and still infects one out of three people in the world, she said.

Influenza, on the other hand, creates a pandemic every year, since it has different variants that spread throughout the world. It is controlled, however, with updated flu vaccines that target the new strains annually. Influenza hasn't mutated to a benign disease since it still causes thousands of deaths each year.

COVID-19 did something that is relatively rare for a disease in the history of the world.

"It started in a completely susceptible world population" that didn't have any immunity, Maldonado said.

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Whether a population enters an endemic phase depends on the virus and its variants, the sustainability of mitigation measures such as vaccines, and the attitudes of people toward the disease, she said.

An endemic SARS-CoV-2/COVID-19 virus could become highly transmissible but relatively benign, depending on how it evolves.

"The common cold can cause hundreds of millions of cases annually, but it doesn't put people into the hospital," she said.

COVID-19 could become influenza-like, with a high rate of transmissibility and the ability to kill many people. Up to 60,000 people die each year from influenza and its complications, she noted.

But people don't respond to influenza in the same way they currently do to COVID-19.

"We've learned to live with it or to ignore it," Maldonado said.

There's also a widely available and largely effective vaccine for influenza that is adjusted annually to help the body create antibodies against the most prevalent strains.

COVID-19 infection has thus far killed 6 million people worldwide, though the true number of deaths is likely much higher, Maldonado said.

Vaccines against SARS-CoV-2 are highly effective against current strains, but they confer immunity only for a few months before their effectiveness begins to drop off. Immunity starts waning after four to six months for adults. In children ages 12 to 15, two doses offer protection for three to five months, after which a booster shot is needed, she said.

Variants could overcome the immunity afforded by the current vaccines.

Lourdes Santiago, a registered nurse at Stanford Health Care, prepares to administer the Pfizer-BioNTech vaccine to Tia Pavlovic, 15, at Cesar Chavez Ravenswood Middle School in East Palo Alto on May 15, 2021. Photo by Daniela Beltran B.

Endemic COVID-19 will likely be managed with vaccine boosters along with masking, social distancing and all of the other known precautions that protect against the spread of the virus, she said.

It's not yet known how long boosters offer protection or if people will need another booster or sequential boosters. Perhaps a long-term booster would be possible against COVID-19, she said.

Tetanus requires a booster every 10 years, although it is a bacterium and isn't a virus, she said.

When the virus does reach the endemic phase, strategies such as the state's SMARTER plan will need to be nimble and flexible. The $3.2 billion emergency response package includes $1.9 billion of approved funding to equip the state's health care system with supplies and staffing.

Could an endemic virus flare up and cause a pandemic again? It's always possible, Maldonado said. It's also possible the virus could mutate or hybridize and create another pandemic.

"We could see SARS-CoV-2 co-infect with another virus and create another progeny virus," she said.

Virus mutations and transmissions from animals to humans, which some scientists think created the strain of coronavirus that started the pandemic, are also likely to continue, she said. Three recent scientific studies released on Feb. 25 and 26 indicate that SARS-CoV-2 originated in animals at the market in Wuhan, China. The studies, which are in the pre-print stage and haven't yet been published in peer-reviewed journals, are adding to the long-held theory that the virus crossed over from animals to humans.

Maldonado said that such virus transmissions are more possible now because people are encroaching into land and animal habitats they didn't frequent before and come into contact with animals that have diseases that could mutate and infect people.

Maldonado said it's important to learn the lessons of this pandemic and how to deal with public health around the world. Increased funding, expanding public health programs and worldwide conferences to keep on top of emerging infectious diseases will be necessary to fight future pandemics.

Correction: A previous version of this story misstated the percentage of the world's population estimated to have died from COVID-19. It is about 0.07%, or 6 million to date.

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COVID-19: What it means to move from pandemic to endemic

Stanford epidemiologist says that COVID-19, in some form, is likely to persist

by / Palo Alto Weekly

Uploaded: Fri, Mar 4, 2022, 6:50 am
Updated: Tue, Mar 8, 2022, 3:04 pm

The number of COVID-19 cases in California is steadily declining. Mask mandates are being peeled back. And Gov. Gavin Newsom recently unveiled "California SMARTER," a plan outlining a future of public health support during the next COVID-19 phase.

So what will "endemic" rather than "pandemic" COVID-19 look like? That depends on many variables, according to Stanford epidemiologist Dr. Yvonne Maldonado. Much of what will occur depends on what the virus itself will do.

At the moment, we're still in a pandemic phase of the health crisis, said Maldonado, a professor of pediatric infectious diseases and of health research and policy at Stanford.

"For now, we're in a period of declining cases and of increased immunity and there's no other variant of concern in sight" in California, she said. But "we could be heading into an endemic phase or be in the early stages."

The new subvariant of omicron — subvariant BA.2, which is 33% more transmissible than its predecessor — is present in the Bay Area, according to local health administrators, but Maldonado said thus far it hasn't spread widely and there isn't a huge spike in cases. If that metric holds and the number of cases, whether high or low, doesn't spike, then we'll likely be in an endemic phase of the disease.

Endemic doesn't mean the disease is disappearing from within a population. It simply means that the disease is widely circulating with a more or less constant level of cases that don't fluctuate wildly. Rather than fading away, COVID-19 will likely be something we'll continue to live with.

In general, diseases can be endemic to populations in some parts of the world but not others. Cholera is present and endemic in some countries but isn't prevalent in the U.S., for example. Tuberculosis is also an endemic disease and still infects one out of three people in the world, she said.

Influenza, on the other hand, creates a pandemic every year, since it has different variants that spread throughout the world. It is controlled, however, with updated flu vaccines that target the new strains annually. Influenza hasn't mutated to a benign disease since it still causes thousands of deaths each year.

COVID-19 did something that is relatively rare for a disease in the history of the world.

"It started in a completely susceptible world population" that didn't have any immunity, Maldonado said.

Whether a population enters an endemic phase depends on the virus and its variants, the sustainability of mitigation measures such as vaccines, and the attitudes of people toward the disease, she said.

An endemic SARS-CoV-2/COVID-19 virus could become highly transmissible but relatively benign, depending on how it evolves.

"The common cold can cause hundreds of millions of cases annually, but it doesn't put people into the hospital," she said.

COVID-19 could become influenza-like, with a high rate of transmissibility and the ability to kill many people. Up to 60,000 people die each year from influenza and its complications, she noted.

But people don't respond to influenza in the same way they currently do to COVID-19.

"We've learned to live with it or to ignore it," Maldonado said.

There's also a widely available and largely effective vaccine for influenza that is adjusted annually to help the body create antibodies against the most prevalent strains.

COVID-19 infection has thus far killed 6 million people worldwide, though the true number of deaths is likely much higher, Maldonado said.

Vaccines against SARS-CoV-2 are highly effective against current strains, but they confer immunity only for a few months before their effectiveness begins to drop off. Immunity starts waning after four to six months for adults. In children ages 12 to 15, two doses offer protection for three to five months, after which a booster shot is needed, she said.

Variants could overcome the immunity afforded by the current vaccines.

Endemic COVID-19 will likely be managed with vaccine boosters along with masking, social distancing and all of the other known precautions that protect against the spread of the virus, she said.

It's not yet known how long boosters offer protection or if people will need another booster or sequential boosters. Perhaps a long-term booster would be possible against COVID-19, she said.

Tetanus requires a booster every 10 years, although it is a bacterium and isn't a virus, she said.

When the virus does reach the endemic phase, strategies such as the state's SMARTER plan will need to be nimble and flexible. The $3.2 billion emergency response package includes $1.9 billion of approved funding to equip the state's health care system with supplies and staffing.

Could an endemic virus flare up and cause a pandemic again? It's always possible, Maldonado said. It's also possible the virus could mutate or hybridize and create another pandemic.

"We could see SARS-CoV-2 co-infect with another virus and create another progeny virus," she said.

Virus mutations and transmissions from animals to humans, which some scientists think created the strain of coronavirus that started the pandemic, are also likely to continue, she said. Three recent scientific studies released on Feb. 25 and 26 indicate that SARS-CoV-2 originated in animals at the market in Wuhan, China. The studies, which are in the pre-print stage and haven't yet been published in peer-reviewed journals, are adding to the long-held theory that the virus crossed over from animals to humans.

Maldonado said that such virus transmissions are more possible now because people are encroaching into land and animal habitats they didn't frequent before and come into contact with animals that have diseases that could mutate and infect people.

Maldonado said it's important to learn the lessons of this pandemic and how to deal with public health around the world. Increased funding, expanding public health programs and worldwide conferences to keep on top of emerging infectious diseases will be necessary to fight future pandemics.

Correction: A previous version of this story misstated the percentage of the world's population estimated to have died from COVID-19. It is about 0.07%, or 6 million to date.

Comments

Bystander
Registered user
Another Palo Alto neighborhood
on Mar 4, 2022 at 12:23 pm
Bystander, Another Palo Alto neighborhood
Registered user
on Mar 4, 2022 at 12:23 pm

As a quick look around Palo Alto in the few days since the mask mandate ended, people are still wearing masks even when they don't have to such as outside and driving alone in their cars. It will take these people sometime to change their habits because to some extent it is habit rather than any other reason. Go to other areas of the State and the country, and people are abandoning their masks and fears.

As some are still fearing the virus, as far as they are concerned this is still a pandemic. They are overly cautious and attempting to continue to spread fear of new variants. To those people, ask them what will allow them to have enough peace of mind to remove their masks and they seem to have no real idea, either by time, or by numbers, or by news.

There will be a time when entering a bank wearing a mask will be reason to expect a robbery. We are far from that yet.


The Tiger
Registered user
Midtown
on Mar 4, 2022 at 1:03 pm
The Tiger, Midtown
Registered user
on Mar 4, 2022 at 1:03 pm

“Attempting to continue to spread fear of new variants”. You should rephrase this statement or complete delete it.. I still wear mask because I am at high risk of being infected, prudent, and would rather be safe than sorry. The last thing I would want to do is to sow fear amongst the members of the community.


The Tiger
Registered user
Midtown
on Mar 4, 2022 at 1:10 pm
The Tiger, Midtown
Registered user
on Mar 4, 2022 at 1:10 pm

I still wear mask because I am at high risk of being infected. I am also being prudent since technically we’re still in pandemic mode. I would rather be safe than sorry for now. Finally, I have no intention of sowing fear amongst members of the community.


Paul
Registered user
another community
on Mar 4, 2022 at 1:52 pm
Paul, another community
Registered user
on Mar 4, 2022 at 1:52 pm

"COVID-19 infection has thus far killed 1% of the world's population, an estimated 5 million people,"

One percent of the world's population would be 79 million people, so either the percentage or the number of people is wrong, here.

By the way, the commentor who said the people are trying to spread fear is either wildly misinformed or is being malicious; best to ignore them.


Bystander
Registered user
Another Palo Alto neighborhood
on Mar 5, 2022 at 7:54 am
Bystander, Another Palo Alto neighborhood
Registered user
on Mar 5, 2022 at 7:54 am

People are trying to spread fear, rather than allow us to make up our own minds. If I want to know what is going on I can look it up myself. I do not need to be reminded that "it's still with us, it hasn't gone anywhere" everytime I look at social media or turn on the news. Yes, it is still with us, but reminding us about it for 2 years on a daily basis is spreading fear and not helpful.


John B. Sails
Registered user
Midtown
on Mar 5, 2022 at 8:28 am
John B. Sails, Midtown
Registered user
on Mar 5, 2022 at 8:28 am

Agree strongly with Bystander. The ultra-cautious and extremely sensitive appear to be unable to accept criticism. I really do not think that this yes, fear, should be the preferred role model for defeating COVID or any societal obstacle for that matter...


Sue Dremann
Registered user
Palo Alto Weekly staff writer
on Mar 8, 2022 at 11:15 am
Sue Dremann, Palo Alto Weekly staff writer
Registered user
on Mar 8, 2022 at 11:15 am

Hi Paul,

Thank you for pointing out that the world's population number in the story is incorrect. I've updated the story with a correction.


staying home
Registered user
Crescent Park
on Mar 8, 2022 at 12:03 pm
staying home, Crescent Park
Registered user
on Mar 8, 2022 at 12:03 pm

Information does not equal fear mongering. Nor does taking pre-cautions mean I am afraid. I don't fear an accident on my bicycle but I still wear a helmet (not mandated for my age). I don't fear a car crash, but I still wear a seatbelt. I don't (didn't) go into work when I have the flu. Facts enable informed decisions.


Bystander
Registered user
Another Palo Alto neighborhood
on Mar 8, 2022 at 1:58 pm
Bystander, Another Palo Alto neighborhood
Registered user
on Mar 8, 2022 at 1:58 pm

Staying home.

Thank you for making informed decision on your helmet and seatbelts. Good decision for you and everyone else.

However, we are not bombarded daily with emails, news items, social media posts, County health advisories, etc. about the need to wear a helmet and seatbelts. I also do not get the same bombardment about flu shots, shingles shots, or other health screenings either.

We are going to have to live with Covid. The clue is that we are going to have to live and Covid is now a fact of life. I hope you and I both do not have bike/car accidents, and I hope that we both do not get a bad dose of Covid. But the reality is we are going to have to step out into the world again and live our lives.

Fear mongering is no longer going to work. In fact, the more we are bombarded with news, the more likely we are to turn off the news. The information is there if we need it and we can choose for ourselves what our plans are going to be moving forward. I don't need any pictures of car crashes, smashed bike helmets, or images of needles going into arms any more. I got the memo, I don't need it repeated several times each day.


Gracie
Registered user
Mountain View
on Mar 8, 2022 at 11:31 pm
Gracie, Mountain View
Registered user
on Mar 8, 2022 at 11:31 pm

Just an FYI, many people are wearing masks because it's allergy season, and they have discovered that masks do a fantastic job of filtering out pollen. That's why I'm wearing a mask even when I'm bicycling. It's a blessing not to be besieged by allergy symptoms when I step out of the filtered air in my home.


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