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“Natural” herd immunity: the worst Covid-19 scenario for 2020



This is the year-end list season. Usually, the Vox science team will have a good time and compile a list of bad health and science ideas that should be listed at the end of the year. These ideas should end at the end of the year. In the past, we have been targeting homeopathic medicines, declaring it’s time to end the relevance of the fatal flaws in the Stanford prison experiment and dispel the myths about climate change. However, this year, we only have one goal for smart demolition.

By the end of 2020, let us discard the idea of ​​using herd immunity acquired through natural infection as a means of fighting the Covid-1

9 pandemic. Use many words to describe a simple, terrifying idea: If more people (especially young and less risky) are infected with the coronavirus and become immune as a result, we can end the pandemic as soon as possible.

In response to the pandemic, this idea is unprecedented. Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization, said in October: “In the history of public health, herd immunization has never been used as a strategy to respond to an epidemic, let alone There is a pandemic.” “This is scientifically and morally problematic.”

However, it still maintains a dominant position-especially in the White House.

Former White House adviser Scott Atlas (Scott Atlas), a neuroradiologist, not an epidemiologist, specifically called for more infections. “It is a good thing when young, healthy people are infected,” Atlas said in an interview with San Diego news station KUSI-TV in July. “The goal is not to eliminate all cases. This is unreasonable. If we only protect those who are about to face serious complications, it is not necessary.”

Let us be clear, when young people are sick, this is not a “good thing”. First, some of these young people may die, many more may become seriously ill, and some of them who are not yet understood may suffer long-term consequences. The more people infected, the greater the chance of a rare and terrible event, for example, a 4-month-old brain is swelling after testing positive for Covid-19. For this reason, among other things, trying to infect only young people or low-risk groups is a difficult game.

Why boosting cattle immunity through natural infection is a bad idea

There is an almost understandable case, why some people would implement a cattle immunization strategy. We are cut off from those we care about, businesses are harmed, education is harmed, and so is our mental health. What if we can go back to certain parts of normal life and control the risk of those who are least likely to be harmed?

This idea proved to be reckless. Sweden is a country that pursues a more lenient strategy on the issue of social distancing, and it has the highest Covid-19 death rate in Europe.

Take a look at what happened in Manaus, Brazil: This city of approximately 2 million people has experienced one of the most severe and unstoppable Covid-19 outbreaks in the world. Now, researchers estimate that 44% to 66% of the city’s population is infected with the virus, which means that herd immunity may have been achieved there (another estimate is that the infection rate is 76%). But during the epidemic, the number of deaths in Manaus this year was four times the normal number.

More typically, the term “group immunity” is mentioned in vaccination campaigns against infectious viruses such as measles. This concept can help public health officials think mathematically about how many people in the population need to be vaccinated to prevent disease outbreaks. It is not intended to be used to control a pandemic through natural infection. Here are five reasons:

  1. Even if we can limit access to people who are least likely to die from Covid-19, that population can still suffer huge consequences from infection-such as hospitalization, long-term symptoms, organ damage, lost jobs, high medical expenses, yes. ,death.
  2. Cattle immunity is an extremely high standard for resisting natural infections. There is no single, perfect estimate that can indicate that several percent of people in the United States have been infected with this virus. However, from everyone’s point of view, it is far from reaching the number required for cattle immunity. The US Centers for Disease Control and Prevention (CDC) now estimates that there are 91 million SARS-CoV-2 infections in the United States, accounting for approximately 27% of the total population (although this may be an overestimation). It takes about 60% of the population to achieve herd immunity. This is a rough guess; it could be higher. So, we are halfway there. Who wants to double the damage this virus has already caused? In the United States, more than 330,000 people have died. (In addition, herd immunization does not work nationwide, but on a per-community basis. In other words, some communities are still much more vulnerable than others.)
  3. Scientists don’t know how long the naturally acquired immunity to this virus lasts, or how long a common reinfection may last. If immunity declines and the re-infection rate is high, it will be more difficult to build up herd immunity.
  4. Through the pandemic, we may exceed the herd immunity threshold. Once the cattle immune threshold is reached, it does not mean that the pandemic is over. Bill Hanage, an epidemiologist at Harvard University, told me: “This means that, on average, each infection causes less than one infection.” “If you have infected a million people, then Will be of limited use.” If each infection causes 0.8 new infections on average, the epidemic will slow down. But 0.8 is not zero. According to Hannagar’s example, if one million people are infected when the herd is immunized, those who are already infected may infect another 800,000 people.
  5. Herd immunization strategies may harm some groups more than others. Someone may experience a serious Covid-19 case for multiple reasons. It’s not just age-diseases such as diabetes and high blood pressure also exacerbate risks. The same is true for social factors, including poverty, working conditions and imprisonment.

In the United States, severe Covid-19 deaths have severely affected minorities and vulnerable groups. The risk of encouraging cattle immunity through coronavirus infection may isolate these marginalized communities from society because they may not be safe in a more permissive environment. Even worse, we run the risk of sacrificing their health in the name of achieving sufficient immunity to control the virus.

Soon, thanks to the vaccine, immunization of the herd will be a good thing

Fortunately, we now have a way to boost the immunity of cattle without the risk of infection: vaccines. Unlike the immunity conferred by actual viral infections, the immunity gained through vaccines will not bring the cost of disease and death. The vaccine is safe. Although they will not reverse the trend of this epidemic overnight, they will help end the epidemic.

We still need to do some hard waiting. The introduction of vaccines will be slow. Throughout 2020, “herd immunity” is used as a shorthand for “let the pandemic spread”. Some people also talk about the usual false wishful thinking. They say that herd immunity has been reached, or earlier than scientists say, or can be achieved without causing huge losses. Yes, the economic constraints of the pandemic were and are still painful. But this is also true: the government could have provided more help.

Soon, as we jointly and safely move towards this goal through vaccines, cattle immunity will become good news. With the distribution of vaccines, herd immunization will develop in a controlled and ethical manner. The pandemic will abate.

And, don’t forget: the call to increase the immunity of the herd through infection is a terrible, terrible idea. We will not repeat it in the future.




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