So what the study and charts say is that if you keep the large majority of your population locked up at home and only allow a small percentage of your population out (the connectivity factor CV) --- then a large portion of the population that you allow out and about will be immune after getting sick. This, of course, is based on the premise that 80% of your communities is strictly locked-up at home and less than 20% is moving around as essential workers. In this manner only 20% of your overall population needs to be immune to provide "herd Immunity" -- but it still means that 80% of your population needs to be locked-down forever. Any reasonable scientist knows that the minimum percentage to achieve herd immunity for a infectious disease is 50% across an entire community with no mitigation... this is easily proved with mathematical models. For most diseases the minimum level is above 70%.
no... it does not say you have to lock up 80 percent... it says because of the way natural immunity works... you can get to herd immunity if only 20 percent of the population have become immune. 2. You seem to not understand that these authors specifically stated that natural immunity works differently than vaccine immunity. You are applying math from the vaccine (wrong) model. A crucial caveat in exporting these calculations to immunization by natural infection is that natural infection does not occur at random. 30 Individuals who are more susceptible or more exposed are more prone to be infected and become immune, which lowers the threshold (14). In our model, the herd immunity threshold declines sharply when coefficients of variation increase from 0 to 2 and remains below 20% for more variable populations. The amplitude of the decline depends on what property is heterogeneous and how it is distributed but the downwards trend is robust (Figures 3 and S22)
I believe that we are heading for herd immunity, if there will just be more spreading fairly quickly. We may be fairly near herd immunity even as we speak. --We don't know yet---
My thought is that we are around 20 percent infections now (60 some million)--not the 2.5 million that have been recorded.
Spain's coronavirus antibodies study adds evidence against natural herd immunity https://www.cnn.com/2020/07/06/health/spain-coronavirus-antibody-study-lancet-intl/index.html Spain's large-scale study on the coronavirus indicates just 5% of its population has developed antibodies, strengthening evidence that a so-called herd immunity to Covid-19 is "unachievable," the medical journal the Lancet reported on Monday. The findings show that 95% of Spain's population remains susceptible to the virus. Herd immunity is achieved when enough of a population has become infected with a virus or bacteria -- or vaccinated against it -- to stop its circulation. The European Center for Disease Control told CNN that Spain's research, on a nationwide representative sample of more than 61,000 participants, appears to be the largest study to date among a dozen serological studies on the coronavirus undertaken by European nations. It adds to the findings of an antibody study involving 2,766 participants in Geneva, Switzerland, published in the Lancet on June 11. here have been similar studies in China and the United States and "the key finding from these representative cohorts is that most of the population appears to have remained unexposed" to Covid-19, "even in areas with widespread virus circulation," said a Lancet commentary published along with Spain's findings. "In light of these findings, any proposed approach to achieve herd immunity through natural infection is not only highly unethical, but also unachievable," said the Lancet's commentary authors, Isabella Eckerle, head of the Geneva Centre for Emerging Viral Diseases, and Benjamin Meyer, a virologist at the University of Geneva. Doctors are uncertain whether having antibodies to the coronavirus means someone cannot be infected again. It's not clear how long or how well antibodies protect people from the virus. Spain's peer-reviewed study began in April while the nation remained on a strict lockdown, and was conducted by leading government research and epidemiological agencies. "The relatively low seroprevalence observed in the context of an intense epidemic in Spain might serve as a reference to other countries. At present, herd immunity is difficult to achieve without accepting the collateral damage of many deaths in the susceptible population and overburdening of health systems," the report reads. The Spanish study's lead author, Marina Pollán, who is director of the National Center for Epidemiology, told CNN: "Some experts have computed that around 60% of seroprevalence might mean herd immunity. But we are very far from achieving that number." Spain has been one of the countries in Europe hit hardest by the coronavirus, with more than 28,000 deaths and 250,000 cases. The Lancet published results of the first phase of Spain's study, conducted from April 27 to May 11, which showed a nationwide antibody prevalence of 5%. But the Madrid metropolitan area, the hardest-hit in the country by Covid-19, had more than 10% prevalence, and densely urban Barcelona had 7%, while many other coastal provinces had far lower rates. Similarly, Geneva's prevalence was 10.8% in the Swiss study conducted from April to early May, the Lancet reported. "With a large majority of the population being infection naïve, virus circulation can quickly return to early pandemic dimensions in a second wave once measures are lifted," the Lancet's commentary authors Eckerle and Meyer wrote of the findings. Spain's second study phase results were released on June 4, showing a 5.2% national prevalence, just slightly higher than in the first phase. The results from the third and final phase were made public on Monday; they showed that national prevalence remained at 5.2%, Pollán said.
So are you or the author implying they should have been closer to herd immunity even though they locked down? I don't understand that argument at all. And if anything the data is consistent with the possibility of natural herd immunity because the harder hit cities had more antibodies. 1. From what I just read they had a nationwide lock down so I would have to wonder why the author of you would expect them to achieve herd immunity? If you are avoiding exposure you are much less likely to get herd immunity... correct? 2.. the immunity level remained the same at 3 different times. I would like to have seen that broken down better. 3. Recent studies show that T cells do the fight of the virus instead of the antibodies. So 15% may be immune. 4. Models indicate herd immunity can be achieve at much lower levels from natural infection rather so vaccine models don't apply. In short this is the data is nothing knew and expected from every locked down country. You are not going to move toward herd immunity and avoid a second wave if you lock down hard. And although they have done a great job with a strict lockdown... they are still having to lock down regions as the virus spikes.