'Azhar designation proof of commitment against terror'

Beijing, Mar 21: China reported no domestically transmitted coronavirus cases for the third consecutive day even as seven more fatalities have been confirmed, taking the death toll in the country to 3255.

No new domestically transmitted cases of COVID-19 were reported on the Chinese mainland for the third day in a row on Friday, China's National Health Commission (NHC) said on Saturday.

The overall confirmed cases on the mainland had reached 81,008 by the end of Friday, which included 3,255 who died, 6,013 patients still undergoing treatment, 71,740 patients who had been discharged after recovery, the NHC said.

The NHC said 41 new confirmed COVID-19 cases were reported on the Chinese mainland on Friday from the people arriving from abroad, taking the total number of imported cases to 269.

The coronavirus can stay aloft for hours in tiny droplets in stagnant air, infecting people as they inhale, mounting scientific evidence suggests.

This risk is highest in crowded indoor spaces with poor ventilation, and may help explain superspreading events reported in meatpacking plants, churches and restaurants.

It’s unclear how often the virus is spread via these tiny droplets, or aerosols, compared with larger droplets that are expelled when a sick person coughs or sneezes, or transmitted through contact with contaminated surfaces, said Linsey Marr, an aerosol expert at Virginia Tech.

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Aerosols are released even when a person without symptoms exhales, talks or sings, according to Marr and more than 200 other experts, who have outlined the evidence in an open letter to the World Health Organization.

What is clear, they said, is that people should consider minimizing time indoors with people outside their families. Schools, nursing homes and businesses should consider adding powerful new air filters and ultraviolet lights that can kill airborne viruses.

What does it mean for a virus to be airborne?

For a virus to be airborne means that it can be carried through the air in a viable form. For most pathogens, this is a yes-no scenario. HIV, too delicate to survive outside the body, is not airborne. Measles is airborne, and dangerously so: It can survive in the air for up to two hours.

For the coronavirus, the definition has been more complicated. Experts agree that the virus does not travel long distances or remain viable outdoors. But evidence suggests it can traverse the length of a room and, in one set of experimental conditions, remain viable for perhaps three hours.

How are aerosols different from droplets?

Aerosols are droplets, droplets are aerosols — they do not differ except in size. Scientists sometimes refer to droplets fewer than 5 microns in diameter as aerosols. (By comparison, a red blood cell is about 5 microns in diameter; a human hair is about 50 microns wide.)

From the start of the pandemic, the WHO and other public health organizations have focused on the virus’s ability to spread through large droplets that are expelled when a symptomatic person coughs or sneezes.

These droplets are heavy, relatively speaking, and fall quickly to the floor or onto a surface that others might touch. This is why public health agencies have recommended maintaining a distance of at least 6 feet from others, and frequent hand washing.

But some experts have said for months that infected people also are releasing aerosols when they cough and sneeze. More important, they expel aerosols even when they breathe, talk or sing, especially with some exertion.

Scientists know now that people can spread the virus even in the absence of symptoms — without coughing or sneezing — and aerosols might explain that phenomenon.

Because aerosols are smaller, they contain much less virus than droplets do. But because they are lighter, they can linger in the air for hours, especially in the absence of fresh air. In a crowded indoor space, a single infected person can release enough aerosolized virus over time to infect many people, perhaps seeding a superspreader event.

For droplets to be responsible for that kind of spread, a single person would have to be within a few feet of all the other people, or to have contaminated an object that everyone else touched. All that seems unlikely to many experts: “I have to do too many mental gymnastics to explain those other routes of transmission compared to aerosol transmission, which is much simpler,” Marr said.

Can I stop worrying about physical distancing and washing my hands?

Physical distancing is still very important. The closer you are to an infected person, the more aerosols and droplets you may be exposed to. Washing your hands often is still a good idea.

What’s new is that those two things may not be enough. “We should be placing as much emphasis on masks and ventilation as we do with hand washing,” Marr said. “As far as we can tell, this is equally important, if not more important.”

Should I begin wearing a hospital-grade mask indoors? And how long is too long to stay indoors?

Health care workers may all need to wear N95 masks, which filter out most aerosols. At the moment, they are advised to do so only when engaged in certain medical procedures that are thought to produce aerosols.

For the rest of us, cloth face masks will still greatly reduce risk, as long as most people wear them. At home, when you’re with your own family or with roommates you know to be careful, masks are still not necessary. But it is a good idea to wear them in other indoor spaces, experts said.

As for how long is safe, that is frustratingly tough to answer. A lot depends on whether the room is too crowded to allow for a safe distance from others and whether there is fresh air circulating through the room.

What does airborne transmission mean for reopening schools and colleges?

This is a matter of intense debate. Many schools are poorly ventilated and are too poorly funded to invest in new filtration systems. “There is a huge vulnerability to infection transmission via aerosols in schools,” said Don Milton, an aerosol expert at the University of Maryland.

Most children younger than 12 seem to have only mild symptoms, if any, so elementary schools may get by. “So far, we don’t have evidence that elementary schools will be a problem, but the upper grades, I think, would be more likely to be a problem,” Milton said.

College dorms and classrooms are also cause for concern.

Milton said the government should think of long-term solutions for these problems. Having public schools closed “clogs up the whole economy, and it’s a major vulnerability,” he said.

“Until we understand how this is part of our national defense, and fund it appropriately, we’re going to remain extremely vulnerable to these kinds of biological threats.”

What are some things I can do to minimize the risks?

Do as much as you can outdoors. Despite the many photos of people at beaches, even a somewhat crowded beach, especially on a breezy day, is likely to be safer than a pub or an indoor restaurant with recycled air.

But even outdoors, wear a mask if you are likely to be close to others for an extended period.

When indoors, one simple thing people can do is to “open their windows and doors whenever possible,” Marr said. You can also upgrade the filters in your home air-conditioning systems, or adjust the settings to use more outdoor air rather than recirculated air.

Public buildings and businesses may want to invest in air purifiers and ultraviolet lights that can kill the virus. Despite their reputation, elevators may not be a big risk, Milton said, compared with public bathrooms or offices with stagnant air where you may spend a long time.

If none of those things are possible, try to minimize the time you spend in an indoor space, especially without a mask. The longer you spend inside, the greater the dose of virus you might inhale.

Washington, Jul 14: The United States has the biggest Covid-19 testing programme in the world, better than big countries like Russia, China, India and Brazil, President Donald Trump said on Monday, asserting that America has "just about the lowest mortality rate" due to the disease in the world.

"We have one of the lowest mortality rates anywhere," Trump said at a White House roundtable. More than 34 lakh Americans have tested positive for Covid-19 so far and over 1,37,000 have died due to the disease, both of which are the largest numbers among all the countries.

The huge number of positive cases, the president said, is due to the massive testing efforts undertaken by his administration, more extensive than any other country.

"We test more than anybody by far. And when you test, you create cases. So we have created cases. I can tell you that some countries, they test when somebody walks into a hospital sick or walks into maybe a doctor's office, but usually a hospital. That is the testing they do, so they do not have cases, whereas we have all these cases. So, it is a double-edged sword," he said.

At the same time, the United States has the lowest mortality rate or just about the lowest mortality rate due to the disease in the world, Trump added. "We are doing a great job. We are doing very well with vaccines and we are doing very, very well with therapeutics. I think we are going to have some very good information coming out soon," he said in response to a question.

"But we have the best and certainly, by far, the biggest testing programme anywhere in the world. If you tested China or Russia or any of the larger countries, if you just tested India, as an example, the way we test, you would see numbers that would be very surprising. Brazil too. You know, Brazil is going through a big problem, but they do not do testing like we do," Trump said.

"So we do the testing and by doing the testing, we have tremendous numbers of cases. As an example, we have done 45 million tests. If we did half that number, you would have half the cases probably -- around that number. If we did another half of that, you would have half the numbers. Everyone would be saying, 'Oh, we are doing so well on cases'," he added.

Responding to a question, Trump said what China did to the world should not be forgotten.

"I think what China has done to the world with what took place -- the China plague -- you can call it the China virus, you can call it whatever you want to call it. It has about 20 different names. What they did to the world should not be forgotten," he said.

The trade deal with China that was signed early this year remains intact, the president said. "It is intact, they (China) are buying. Whether they buy or not, that is up to them. They are buying," he said.