Since it's quiet today, here are some excerpts from a few more articles.
_________________239 Experts With 1 Big Claim: The Coronavirus Is Airborne
The W.H.O. has resisted mounting evidence that viral particles floating indoors are infectious, some scientists say. The agency maintains the research is still inconclusive. ...
The coronavirus is finding new victims worldwide, in bars and restaurants, offices, markets and casinos, giving rise to frightening clusters of infection that increasingly confirm what many scientists have been saying for months: The virus lingers in the air indoors, infecting those nearby.
If airborne transmission is a significant factor in the pandemic, especially in crowded spaces with poor ventilation, the consequences for containment will be significant. Masks may be needed indoors, even in socially distant settings. Health care workers may need N95 masks that filter out even the smallest respiratory droplets as they care for coronavirus patients.
Ventilation systems in schools, nursing homes, residences and businesses may need to minimize recirculating air and add powerful new filters. Ultraviolet lights may be needed to kill viral particles floating in tiny droplets indoors.
The World Health Organization has long held that the coronavirus is spread primarily by large respiratory droplets that, once expelled by infected people in coughs and sneezes, fall quickly to the floor.
But in an open letter to the W.H.O., 239 scientists in 32 countries have outlined the evidence showing that smaller particles can infect people, and are calling for the agency to revise its recommendations. The researchers plan to publish their letter in a scientific journal next week. ...
”We’ve known since 1946 that coughing and talking generate aerosols,” said Linsey Marr, an expert in airborne transmission of viruses at Virginia Tech.
Scientists have not been able to grow the coronavirus from aerosols in the lab. But that doesn’t mean aerosols are not infective, Dr. Marr said: Most of the samples in those experiments have come from hospital rooms with good air flow that would dilute viral levels.
In most buildings, she said, “the air-exchange rate is usually much lower, allowing virus to accumulate in the air and pose a greater risk.”
The W.H.O. also is relying on a dated definition of airborne transmission, Dr. Marr said. The agency believes an airborne pathogen, like the measles virus, has to be highly infectious and to travel long distances.
People generally “think and talk about airborne transmission profoundly stupidly,” said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health.
“We have this notion that airborne transmission means droplets hanging in the air capable of infecting you many hours later, drifting down streets, through letter boxes and finding their way into homes everywhere,” Dr. Hanage said.
Experts all agree that the coronavirus does not behave that way. Dr. Marr and others said the coronavirus seemed to be most infectious when people were in prolonged contact at close range, especially indoors, and even more so in superspreader events — exactly what scientists would expect from aerosol transmission.https://www.nytimes.com/2020/07/04/health/239...The Pandemic’s Big Mystery: How Deadly Is the Coronavirus?
Even with more than 500,000 dead worldwide, scientists are struggling to learn how often the virus kills. ...
A firm estimate could help governments predict how many deaths would ensue if the virus spread out of control. The figure, usually called the infection fatality rate, could tell health officials what to expect as the pandemic spreads to densely populated nations like Brazil, Nigeria and India.
In even poorer countries, where lethal threats like measles and malaria are constant and where hard budget choices are routine, the number could help officials decide whether to spend more on oxygen concentrators or ventilators, or on measles shots and mosquito nets.
The question became even more complex last month, when the Centers for Disease Control and Prevention released data suggesting that for every documented infection in the United States, there were 10 other cases on average that had gone unrecorded, probably because they were very mild or asymptomatic.
If there are many more asymptomatic infections than once thought, then the virus may be less deadly than it has appeared. But even that calculation is a difficult one. ...
At present, countries have very different case fatality rates, or C.F.R.’s, which measure deaths among patients known to have had Covid-19. In most cases, that number is highest in countries that have had the virus the longest.
According to data gathered by The New York Times, China had reported 90,294 cases as of Friday and 4,634 deaths, which is a C.F.R. of 5 percent. The United States was very close to that mark. It has had 2,811,447 cases and 129,403 deaths, about 4.6 percent.
Those percentages are far higher rates than the 2.5 percent death rate often ascribed to the 1918 flu pandemic. Still, it is difficult to measure fatality rates during pandemics, especially at the beginning.
In the chaos that ensues when a new virus hits a city hard, thousands of people may die and be buried without ever being tested, and certainly without them all being autopsied.
It is never entirely clear how many died of the virus and how many died of heart attacks, strokes or other ills. That has happened in both New York City and in Wuhan, China, where the outbreak began. ...
Ten sizable countries, most of them in Western Europe, have tested bigger percentages of their populations than has the United States, according to Worldometer, which gathers statistics. They are Iceland, Denmark, Spain, Portugal, Belgium, Ireland, Italy, Britain, Israel and New Zealand.
But their case fatality rates vary wildly: Iceland’s is less than 1 percent, New Zealand’s and Israel’s are below 2 percent. Belgium, by comparison, is at 16 percent, and Italy and Britain at 14 percent. ...
So far, in most countries, about 20 percent of all confirmed Covid-19 patients become ill enough to need supplemental oxygen or even more advanced hospital care, said Dr. Janet Diaz, head of clinical care for the W.H.O.’s emergencies program. ...
Death rates are expected to be lower in countries with younger populations and less obesity, which are often the poorest countries. Conversely, the figures should be higher in countries that lack oxygen tanks, ventilators and dialysis machines, and where many people live far from hospitals. Those are also often the poorest countries. ...
And now, new factors are being introduced into the equation. For example, new evidence that people with Type A blood are more likely to fall deathly ill could change risk calculations. Type A blood is relatively rare in West Africa and South Asia, and very rare among the Indigenous peoples of South America. ...
... the death rates may ... shift in wealthier northern countries as winter approaches. Most of the spread of the virus in Europe and North America has taken place during mild or warm weather in the spring and summer.
Many experts fear that infections and deaths will shoot up in the fall as colder weather forces people indoors, where they are more likely to infect one another. ...
In each of the eight influenza pandemics to hit the United States since 1763, a relatively mild first wave — no matter what time of year it arrived — was followed by a larger, much more lethal wave a few months later, noted Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.
More than a third of all the people killed by the Spanish flu, which lasted from March 1918 to late 1920, died in the short stretch between September and December 1918 — about six months after a first, relatively mild version of what may have been the same virus broke out in western Kansas.
“We will go much higher in the next 12 to 18 months,” Dr. Osterholm said. Because this is a coronavirus, not influenza, it may not follow the same pattern, but it is “a much more efficient transmitter than influenza.”https://www.nytimes.com/2020/07/04/health/cor...As Coronavirus Slams Houston Hospitals, It’s Like New York ‘All Over Again’
The death toll is lower, but there are echoes of March as cases spike, doctors fall ill and supplies run short. Now, Texas is trying to adapt hard-won lessons while addressing a new set of challenges. ...
Houston’s hospitals have some advantages compared with New York’s in the spring. Doctors know more now about how to manage the sickest patients and are more often able to avoid breathing tubes, ventilators and critical care. But one treatment shown to shorten hospital stays, the antiviral drug remdesivir, is being allocated by the state, and hospitals here have repeatedly run out of it. ...https://www.nytimes.com/2020/07/04/us/coronav...DNA Linked to Covid-19 Was Inherited From Neanderthals, Study Finds
The stretch of six genes seems to increase the risk of severe illness from the coronavirus. ...
A stretch of DNA linked to Covid-19 was passed down from Neanderthals 60,000 years ago, according to a new study.
Scientists don’t yet know why this particular segment increases the risk of severe illness from the coronavirus. But the new findings, which were posted online on Friday
( https://www.biorxiv.org/content/10.1101/2020.... )
and have not yet been published in a scientific journal, show how some clues to modern health stem from ancient history. ...
This piece of the genome, which spans six genes on Chromosome 3, has had a puzzling journey through human history, the study found. The variant is now common in Bangladesh, where 63 percent of people carry at least one copy. Across all of South Asia, almost one-third of people have inherited the segment.
Elsewhere, however, the segment is far less common. Only 8 percent of Europeans carry it, and just 4 percent have it in East Asia. It is almost completely absent in Africa.
It’s not clear what evolutionary pattern produced this distribution over the past 60,000 years. “That’s the $10,000 question,” said Hugo Zeberg, a geneticist at the Karolinska Institute in Sweden who was one of the authors of the new study.
One possibility is that the Neanderthal version is harmful and has been getting rarer over all. It’s also possible that the segment improved people’s health in South Asia, perhaps providing a strong immune response to viruses in the region.
“One should stress that at this point this is pure speculation,” said Dr. Zeberg’s co-author, Svante Paabo, the director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. ...
Last month, researchers compared people in Italy and Spain who became very sick with Covid-19 to those who had only mild infections. They found two places in the genome associated with a greater risk.
( https://www.nytimes.com/2020/06/03/health/cor... )
One is on Chromosome 9 and includes ABO, a gene that determines blood type. The other is the Neanderthal segment on Chromosome 3.
But these genetic findings are being rapidly updated as more people infected with the coronavirus are studied. Just last week, an international group of scientists called the Covid-19 Host Genetics Initiative
( https://www.covid19hg.org/ )
released a new set of data downplaying the risk of blood type. “The jury is still out on ABO,” said Mark Daly, a geneticist at Harvard Medical School who is a member of the initiative.
The new data showed an even stronger link between the disease and the Chromosome 3 segment. People who carry two copies of the variant are three times more likely to suffer from severe illness than people who do not. ...
It’s possible that an immune response that worked against ancient viruses has ended up overreacting against the new coronavirus. ...
Dr. Paabo said the DNA segment may account in part for why people of Bangladeshi descent are dying at a high rate of Covid-19 in the United Kingdom.
It’s an open question whether this Neanderthal segment continues to keep a strong link to Covid-19 as Dr. Zeberg and other researchers study more patients. https://www.nytimes.com/2020/07/04/health/cor...