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Home / Health / The brutal COVID-19 surge has killed many people and is now helping to build herd immunity

The brutal COVID-19 surge has killed many people and is now helping to build herd immunity



As coronavirus cases have plummeted across the country, and the total number of daily vaccinations reached 1.7 million Americans, and they are still rising, health experts are increasingly sending out a new tone in epidemiological assessments: optimism.

Dr. Paul Offit, a vaccine expert at the Children’s Hospital of Philadelphia, said: “I may be wrong, but I don’t think we will see the fourth surge.” “I think we have seen the worst.”

While remaining cautious, many epidemiologists and other scientists said they increasingly hope that the rest of 2021 will not repeat the nightmare of last year.

Experts say that the arrival of spring may help the continued sharp decline in coronavirus cases because the warmer weather allows people to spend more time outdoors and creates a less friendly environment for the virus.

But, paradoxically, the biggest factor is that the country spent a lot of time on prevention last year.

According to Offit estimates, although 12% of Americans have received at least one dose of the COVID-19 vaccine (nearly 20% of Alaskans), more people (about 35% of the country’s population) have been infected with the coronavirus. Studies have found that people who survive COVID-19 have immunity for several months, although it may last longer.

Dr. George Rutherford, an epidemiologist at the University of California, San Francisco, said that one of the reasons for the rapid decline in California cases is “due to naturally acquired immunity, mainly in Southern California.” He estimated that 50% of Los Angeles County residents were infected with the virus at some point.

Rutherford recently said: “We are really talking about something that sounds like herd immunity, although this kind of real herd immunity is far away in the future.”

When many people are immune to the extent that the virus cannot find a new host and stop spreading, thereby achieving community-wide protection, herd immunity is achieved. Scientists believe that as far as coronavirus is concerned, the threshold may be as high as 90%. Experts say that the United States has not yet reached this threshold, but every step towards this step will slow down the speed of transmission.

Where the worst COVID-19 surge is experienced, the impact may be greatest. According to researchers, more than 12,000 people have been killed after the terrible autumn and winter waves, and it is estimated that 33% to 55% of county residents have been infected with the coronavirus.

Dr. Roger Lewis, director of COVID-19 hospital demand modeling, said those past infections have severely weakened the spread of the coronavirus to the point that they changed the current trend of outbreaks in Los Angeles County, where new cases per day have fallen by five weeks. For the county health bureau.

“If you have the exact same behavior and type of virus transmission that we have now, but we are at the beginning of a pandemic, and no one is immune… we will be in a constant boom,” he said. “The fact is that the number of cases is declining, not rising, because about a third of people in Los Angeles County are immune to COVID.”

But experts warn that the battle is not over yet.

New coronavirus variants can undermine these predictions by demonstrating greater resistance to existing vaccines, or finding a way to spread more easily. Experts say that changes in behavior may also bring good news, because behavior only occurs when people adhere to the preventive measures taken so far.

Dr. Paul Simon, Chief Science Officer of Los Angeles County, said: “I don’t want to give false assurances here,” he pointed out that even if more than one-third of the angels have been infected with Angolinos, there are still 60% The angels are vulnerable. Coronavirus. “Unless they have been vaccinated, they are still vulnerable to infection. I think we need to continue to be vigilant.”

Federal officials say that across the country, coronavirus cases have fallen to the lowest level since late October.

Since the beginning of the pandemic, nearly 30 million Americans have tested positive for the coronavirus, but due to the low level of testing and the fact that many infected people never show symptoms, the actual number of people infected with the virus may be three to four times higher . , The expert said.

A large number of infections paid a high price. The death toll in this country is close to 500,000, far more than any other country in the world, and even more survivors have survived, but continue to suffer the lingering effects of its disease, some of which are serious. Experts say that allowing COVID-19 to run rampantly to quickly achieve herd immunity, as some people advocated at the beginning of the pandemic, will lead to more deaths and chronic health problems.

Simon of Los Angeles County said that it is not yet clear what the herd immunity threshold of this virus is. Some scientists estimate that when 50% of people are immunized, cattle immunity can be achieved, while others believe that the threshold is close to 90. %. He said the uneven geographic distribution of infections may also make certain areas of the county more vulnerable than others.

Simon said in Friday’s briefing: “We don’t yet know what level of vaccination and protection is needed to immunize cattle across the county.” “As we have seen, the number of new cases has dropped sharply. This is the best clue I think we are reaching herd immunity, especially when we see this situation across the county.”

The biggest obstacle to ending the pandemic is the spread of variants of the coronavirus.

Especially if they are more easily spread or less sensitive to vaccines. For example, the B.1.1.7 variant that appeared in the United Kingdom is about 50% more infectious than its predecessor, and may break out in places where large numbers of people are still susceptible to disease.

Dr. Peter Hotz, Dean of the School of Tropical and Tropical Medicine at Baylor College of Medicine, said he believes that by August, visiting relatives and friends will be normal and safe. But because of these variants, he warned people to “beware of the March plot.”

In a recent interview with the American Medical Association, he said: “I think this is the biggest crisis we are currently facing in the COVID-19 pandemic.” “It is as bad as 2020, and now we are looking for variants of this epidemic. Version 2.0.”

But others are more optimistic. Offit said he will worry about whether people who have been infected with COVID-19 or have been vaccinated will be hospitalized due to infection caused by the new mutation.

He said: “This line has not been crossed.” “You just want to get people out of the hospital. So far, there doesn’t seem to be any immunity that can escape the disease or vaccine-induced.”

At the UCSF Medical Department’s COVID seminar last week, infectious disease expert Dr. Monica Gandhi simply said: “Don’t worry about these mutations.”

Offit said he is hopeful about the whole summer and as more people receive the vaccination. Offit said: “What worries me a little is that when you get cold again in mid-September, there may be variants.” People no longer wear masks and become physically alienated.

Dr. Rochelle Walensky, director of the US Centers for Disease Control and Prevention, cautioned against seeing the declining trend of cases as a reason for abandoning shelter and other safety precautions.

In an interview with the Journal of the American Medical Association, Walensky said that she hopes to do the best, but also to warn of the worst-people will stop wearing masks and alienate their bodies prematurely, many people will prematurely announce that they already have Enough pandemic, will not be vaccinated.

Varensky said: “It will depend on 330 million people.” “Because I am really hopeful about what will happen in March and April, but I do know that it can get bad-so fast. We saw it in November. We saw it in December. We saw what would happen.”

Dr. Annabelle de Saint-Maurice, a pediatric infectious disease expert at the University of California, Los Angeles, said she sympathized with officials trying to make a fine distinction between maintaining morale and not making people feel so optimistic that they lowered their vigilance.

She said that, especially in Los Angeles, this number has improved greatly, but it remains as high as it was during the deadly summer surge.

She said: “This is a reason to celebrate. You want people to celebrate it, but you want them to keep a certain distance from them while wearing a mask.”


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