Is it risky to invite unvaccinated people home for the holidays?
1:22
(CNN) - The
United States went through waves, spikes and spikes of covid-19 throughout the pandemic, and now there are concerns that the country may be entering a new winter rebound.
Scientists sometimes know what factors are driving a new increase in cases, but some increases have been inconsistent and difficult to predict.
Scientists suspect that eventually the rise and fall of coronavirus infections could shift to a more typical seasonal pattern.
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This says an expert
Early next year, health authorities plan to start serious conversations about what the end of the pandemic might look like and how we will know when we have reached that point.
The United States has not yet reached that point.
As of this Thursday, the United States registered an average of 121,084 new cases of covid-19 every day, according to data from Johns Hopkins University.
This is 62% more than a month ago.
Although COVID-19 cases and hospitalizations in the United States declined at the end of the summer surge, they have risen in recent weeks.
More than half of the new hospitalizations in the past month have occurred in the Midwestern states, especially Michigan and Ohio.
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Dr. Laolu Fayanju and his colleagues have treated patients from covid-19 throughout the year.
Now, once again, preparing for a possible surge winter.
"We saw an increase in our numbers in the last month alone at all of our 11 centers in North and South Ohio," Fayanju, a Cleveland, Ohio-based Oak Street Health physician, told CNN.
"So we are seeing an increase."
Scientists have observed "waves" of coronavirus infections during the pandemic fluctuating across regions of the United States, but the factors driving these infection patterns are complex.
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Although no one can predict the future, "we are living in an intracovid world, and in a post-pandemic world, I think what we would see is an endemic infection, not very different from seasonal flu," said Fayanju.
Endemic means that a disease has a constant presence in a population, but does not overwhelm health systems or affect an alarming number of people, as is often the case in a pandemic.
Some scientists point out that human behaviors, such as travel, feed the waves.
Some believe the surges are further proof that Covid-19 is on its way to becoming a seasonal endemic disease, with more cases in the cold winter months, when temperatures outside drop and people gather indoors.
Others argue that seasonal covid-19 waves could be more complex, as there have been both expected winter waves and less-expected summer waves during the pandemic.
"We need more research to unravel all the factors that may link seasonality to COVID-19 cases," Dr. Hawre Jalal, an adjunct professor at the University of Pittsburgh, told CNN.
But there is one thing many scientists agree on: future coronavirus infections could follow seasonal cycles.
"There will always be this underlying seasonal rhythm"
"Seasonality is real," said Dr. Donald Burke, professor and former dean of the University of Pittsburgh Graduate School of Public Health.
"We will be seasonal in the immediate future," Burke said.
A study carried out by researchers in Spain, published in October in the academic journal Nature Computational Science, classifies covid-19 as a "seasonal low-temperature infection."
On the other hand, Burke and his colleague Jalal are co-authors of two articles still in prepress that describe the seasonal patterns of the waves of the pandemic so far and suggest that these patterns may be repeated in later years.
The papers have not been published in a peer-reviewed journal, but were posted online on the medrxiv.org server in July and November.
For the first article, the researchers tracked COVID-19 case counts in the United States, Mexico, and Canada from early 2020 through May 2021 and constructed map visualizations illustrating how many COVID-19 cases and deaths were recorded where and when, visualizing trends in the data and revealing patterns.
The views showed four dominant waves that occurred between March 2020 and May 2021.
The visualizations showed that the first wave of the pandemic in early 2020 occurred largely in the northeastern region of the United States, especially as a surge in cases hit New York City.
Then in the summer, a second wave of infections involved the south and traveled north to the upper Midwest.
"This contradicts the idea that it is a northern, cold season disease," Burke said.
Then in the fall, the third wave began in the Dakotas before spreading across the United States, and then the fourth wave followed, with an increase in winter cases in the northeast, south, and west.
In 2021, despite the authorization of vaccines against covid-19 and the appearance of the delta variant, the spread of cases was somewhat similar to the patterns observed in 2020, although the number of cases and the magnitude of the The changes weren't that big in 2020, the patterns followed a similar seasonal trajectory.
For the second article, the researchers analyzed the growth and decrease patterns of reported covid-19 cases in the United States, Mexico and Canada from January 1, 2020 to October 31, 2021, that is, an additional five months of data compared to the first article.
Covid-19 cases appear to be stagnant.
That doesn't bode well for winter, experts say.
Now, in early December 2021, the case counts covid-19 continue to rise.
For the first time in two months, the US averages more than 100,000 new cases each day shortly after millions of Americans traveling for the Thanksgiving holiday.
"Our modeling of this suggests that the pace of future epidemics will be seasonal, but the amplitude can vary from one year to another or from one era to another. There will always be this seasonal rhythm underlying, being an extra-time in the south but certainly the wave of the north in the winter, "Burke said.
"That will change depending on what proportion of the population is vaccinated, whether or not a new variant arrives at that time, and thus the range will change," he said.
"But the basic rhythm will probably be the same."
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Biden's winter plan for covid-19
Last week, President Joe Biden warned of a potential winter surge of Covid-19, announcing a new strategy aimed at fighting the surge without imposing unpopular shutdowns, as the pandemic approaches its two-year life.
"It does not include closures or lockdowns, but rather widespread vaccinations, boosters, testing and much more," Biden said Thursday.
Biden acknowledged that cases are likely to increase in the coming weeks, as the weather turns colder in much of the country and people begin to gather more indoors.
Biden called for a multi-pronged approach, with a strong emphasis on expanding vaccines to Americans who have resisted getting vaccinated, and to provide boosters to the now eligible population of all adults.
The Biden administration also now requires insurance companies to pay for home tests and has changed the rules for international travel to require travelers flying to the U.S. from another country to test negative for COVID-19. 19 one day, and not the three days, before your departure.
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Scientists, including Jalal of the University of Pittsburgh, have warned that the United States is likely entering another winter wave of COVID-19 at this point.
"As it has done so twice so predictable, it is very likely that a cold wave recur," Jalal told CNN.
"That doesn't mean we should give up and say, 'It's seasonal, we have to accept it.' I think a very important distinction to make is that we have a predictable pattern for it, so we can prepare," Jalal said.
"We can make public health services available before the wave starts."
Although covid-19 could become a seasonal infection in the future, it is important to remember that the world is still fighting a pandemic at this time.
We have not yet entered an endemic phase, said Sen Pei, associate professor of Environmental Health Sciences at Columbia University's Mailman School of Public Health.
So while seasonality could play a role in this year's next winter wave, so could low vaccination rates and the spread of the highly communicable delta variant that dominates the United States and around the world, and of the omicron variant, recently identified.
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"People should take precautions during winter," Pei told CNN.
According to him, this increase may be due to several factors.
"The first will be the appearance of the new omicron variant. I think that is the most important factor at the moment. And the second will be the seasonality of the virus and the impact of climatic factors such as temperature, humidity and also human behavior: people gather more at home during the winter. "
Pei said the vaccination and booster shots " will
also play an important role in reducing severe disease outcomes."
However, once the coronavirus becomes endemic, and the rates of cases, hospitalizations and deaths drop to very low figures, the United States could see more pronounced seasonal patterns of covid-19 in infection rates than those that are give now.
"I think we are still a long way from that," Pei told CNN.
"We will not enter an endemic phase until the vast majority of the population has immunity to the virus, either through infection or vaccination," he said.
"The fatality rate is still very high, much higher than that of the flu, and a large proportion of the population still do not have immunity."
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When will the coronavirus become endemic?
State and local health departments plan to meet with the U.S. Centers for Disease Control and Prevention (CDC) in the new year to discuss what types of data or metrics will be needed to determine what The coronavirus pandemic is over and has passed into an endemic phase, Lori Tremmel Freeman, executive director of the National Association of City and County Health Officials, told CNN on Wednesday.
"We plan to start holding sessions in early January to talk with jurisdictions and their health officials about what we need to think about for the transition from pandemic to endemic. The idea is to anticipate what this will be like in the long term and what parameters and considerations will be used to make the decision, "Freeman said.
As the covid-19 becomes endemic, seasonal patterns that can keep the virus merit discussion, Freeman added.
"We would all like to see that as a possibility, where we are approaching the season and trying to manage one season over the next in terms of severity and other aspects of disease transmission," Freeman said, calling it "crucial." discuss long-term vaccination and mitigation plans.
"There are still so many unknowns that sometimes it seems premature and overwhelming to predict what might happen even to make plans, but it is necessary."
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