Do you underestimate the number of people who are resistant to Covid-19? | World News

DDuring the first wave of the Covid-19 pandemic, cities were generally more affected than small settlements and rural areas. Still in Italy, Rome was relatively spared while the Lombardy village experienced very high illness and death. Later, one village in Lombard, Ferrara El Bongone, stood out for not recording one case of Covid-19 at the height of the waves. No one knows why.

The puzzles are not only in Italian. From the beginning, Covid-19 attacked unevenly around the world, and scientists have sought to understand why. Why are some groups or sectors of groups more vulnerable than others? Or why are some groups relatively protected to solve the problem?

In Observer The end of last weekKarl Friston of University College London, a neuroscientist and Covid-19 modeler, said the relatively low mortality recorded in Germany was due to unknown protection factors, based on a comparison of German and British data. I suggested that it is a thing. “This is like the dark matter of the universe. We can’t see it, but we know we need to be there to explain what we can see.” He said.

While this is a novel perspective, while most experts praise the German blockade and systematic testing regime, others are working hard to identify the factors that are controlling Covid-19’s spread. Are working on and can explain other puzzles. Avoided the deadly first wave Denmark, Austria and the Czech Republic There is no surge in the case Despite early mitigation of lockdown measures, this could shape the way governments manage second wave risks.

One looks clear. There are many reasons why one group is more protected than another. The University of Oxford theoretical epidemiologist Sunetra Gupta believes that immunity built before this outbreak is key. “It has been my intuition for a very long time that there is a lot of mutual protection from serious illness and death conferred by other circulating related bugs,” she says. Its cross protection may not protect a person from infection in the first place, but it can ensure that they experience only relatively mild symptoms.

Due to lack of data on resistance to Covid-19, Gupta’s intuition remains. As we know, antibody testing is late to start, unreliable at first, and to date the results show that the proportion of populations carrying antibodies to the Covid-19 virus is one or two orders of magnitude lower. Suggests that there are many. New arrival, More sensitive antibody test What has been made available in the last few weeks could soon provide a much more accurate situation if deployed sufficiently broadly, but the results to date may have been underestimated. I already have a hint.

First, there was evidence that the virus was endemic in Western European countries, especially France and the US, based on diagnostic tests on post-mortem samples of patients who died in December. About a month earlier than originally thought.. According to a new study, another component of the human immune response, T cells, helps regulate the antibody response and is infected with coronavirus when exposed to Sars-CoV-2, the virus that causes Covid-19. Indicates the memory of.

To Paper published in cell On May 14, researchers at the La Jolla Immunology Institute in California reported that T cells in the blood collected between 2015 and 2018 recognized and reacted with a fragment of the Sars-CoV-2 virus. Did. “These people probably couldn’t see Sars-CoV-2,” said Alessandro Sette, one of the first authors of the paper. “The most valid hypothesis is that this reactivity is a cross-reactivity of Sars-CoV-2 cousins. A common cold that circulates very widely and generally causes relatively mild disease. It’s a coronavirus.”

This discovery The previous one Detecting T-cell reactivity to proteins in the Sars-CoV-2 virus in a group of Charite Hospitals in Berlin, in 83% of Covid-19 patients as well as in 34% of healthy volunteers who tested negative for the virus itself Did.

David Heymann, an epidemiologist at London Health University and advising the World Health Organization on Covid-19, says these results are important, but that cross-reactivity does not always lead to immunity. Please be careful. To follow a large number of people with such cross-reactivity to determine if they should at least be protected from severe illness, but not from infection with Covid-19. Is

However, it is a rational hypothesis that exposure to other coronaviruses may confer protection, Sette said. “I’ve seen it before, such as the H1N1 flu in 2009.” He says the elderly were healthy compared to other age groups in a pandemic, he said, probably their immune system for decades. It had been prepared by exposure to similar strains of influenza from before. The 2009 pandemic is less deadly than any other influenza pandemic in history, An estimated 200,000 people worldwide..

If exposure to other coronaviruses protects Covid-19, variability in that exposure may explain many of the differences in mortality between countries and regions, Gupta said. Exposure to the related viruses that caused the epidemic of severe acute respiratory syndrome (Sars) in 2002-4 may have provided East Asians with some protection from Covid-19, for example.

In late March, Gupta’s group published a paper. What caught the eye was a prediction that was very different from the one the British government had most listened to, the epidemiologist Neil Ferguson and his colleagues at Imperial College London. The Oxford Group has suggested that up to half of the UK’s population may already be infected with Sars-CoV-2, and the Infectious Mortality (IFR)-Percentage of Infected Persons Dead- The disease was not so dangerous, as it showed much lower than the Ferguson group. Neither group had much data at that time, and Gupta says her intention was to emphasize that a wide range of scenarios should be considered in the absence of data.

Two months later, she stands by the model and hopes she’s made it clearer. “The truth is, IFR is not a hardwired property of viruses and their interactions with them,” she says. “It’s the vulnerable part [of the population] That determines the overall average risk of death. For example, when a virus enters an elderly care facility, it spreads and becomes fatal, pushing up IFR. This is so that it is important to understand why some people are resistant but not, so that they can protect vulnerable people.

We are aware of some of these vulnerability factors. Age is the most obvious. Unlike the 2009 flu, older people are particularly vulnerable to Covid-19. This is a fact that may reflect the history of coronavirus exposure in cohorts of different ages. Comorbidities are another and one third are men. According to Garima Sharma of Johns Hopkins University School of Medicine in Baltimore recently announced with a colleague Covid-19 Paper on Sex Differences in Mortality, Women are protected by having a “backup” X chromosome. “Women generally have a stronger immune response because the X chromosome contains a high density of immune-related genes,” she says.

Socioeconomic status, climate, culture, and genetic makeup can also shape vulnerability, as can certain pediatric vaccines and vitamin D levels. And all these factors vary from country to country. The Japanese may have been given some protection, for example, by the habit of bowing rather than shaking hands. And while most of the gender gap is due to biology, according to Sharma, part of it is due to social and behavioral factors, and women can wash their hands and seek preventive care. Will be more likely.

It is also becoming clear that protecting vulnerabilities has made a huge difference to previous results. For example, Italy and Germany have similar proportions of the population over the age of 65 (slightly above 20% of the population in both cases), but the two report significantly different mortality rates. As of May 26, mortality (CFR) (percentage of illnesses that die) is less informative but easier to measure than IFR, as ill people, like the Italian CFR, stand out more than simply infected people .. was aMatch 14%, Compared with 5% in Germany.

Italy is more densely populated than Germany, and Italian homes tend to be smaller than German homes. Many Italians in their 20s and 30s live at home with large families. In other words, the rate of infection of the elderly was high, and death occurred when the emergency room was overwhelmed. This is rare in Germany, and many elderly care facilities have strict isolation systems. In Germany, “they did a better job in keeping the older people protected,” he says. Some estimates are Only 20The German Covid-19 case rate was over 60Compared to 90 and above In Italy.

Recorded uk Second highest mortality rate in Covid-19 after SpainDoes not take good care of the elderly – decided at some point Discharge patient from hospital to care home Without testing them for illness. Although the government’s advice to 1.5 million British citizens with underlying illness that self-isolates for three months from late March may help protect them, Britain’s higher mortality rates are deeper for Gupta. Provided a pastor who reflects the problem. “We just don’t have enough investment in the NHS and its GPs or other frontline individuals to advise vulnerable people,” she says.

She holds her intuition and locks down that’s allreaction And the first line of care and protection of vulnerabilities-which should have been prioritized from the beginning-should now be prioritized. She also thinks that the worst is behind us, and the waves that follow cannot be ruled out, but perhaps not worse than we have ever experienced. In her view, the disease will settle into its own equilibrium and return every winter, perhaps like seasonal flu.

Friston’s model also suggests that the immunity of the population is higher than the data show, but it is unclear to him how long that immunity lasts. A wave that can erupt when immunity is compromised. Hayman continues to be wary of the model he says is too often mistaken for reality in this pandemic, and is waiting for more data. “At the moment, I don’t think anyone can predict the fate of this virus.”