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Scientists believe it’s likely that recovering from coronavirus leaves a person with some immunity, but it’s not clear how strong it is or how long it lasts. Herd immunity is the idea that a disease will stop spreading once enough of a population becomes immune — and is appealing because, in theory, it might provide some protection for those who haven’t been ill.

If more than half of people in Mumbai’s slums had contracted coronavirus, could they be approaching herd immunity — without a vaccine?

One expert thought so.

“Mumbai’s slums may have reached herd immunity,” Jayaprakash Muliyil, chairman of the Scientific Advisory Committee of India’s National Institute of Epidemiology, said, according to a Bloomberg report. “If people in Mumbai want a safe place to avoid infection, they should probably go there.”

But others have been more cautious. David Dowdy, an associate professor in epidemiology at Johns Hopkins Bloomberg School of Public Health, said it was possible that the researchers had used a test that created false positives.

And Om Shrivastav, an infectious diseases expert in Mumbai, cautioned that, less than eight months into the virus’ existence in society, it was too early to make any “decisive, conclusive statements.”

If Mumbai’s slums are on the brink of herd immunity, it has come at a cost. Of India’s more than 2 million coronavirus cases, about 5% of those infections were reported in Mumbai, the country’s commercial capital. As of Monday, more than 6,940 people had died in the city, according to the city’s health authorities.

The risk of a high death toll is exactly why India’s health authorities say the country is not aiming for herd immunity. “Herd immunity can be achieved through immunization — but that is in future,” health official Rajesh Bhushan told reporters last month.

What is herd immunity?

Herd immunity works like this: Assume that each infected person infects three more people. If two of those three people are immune, then the virus is only able to make one person sick. This mean that fewer people are infected by the illness — and over time, even people who aren’t immune end up being protected as they are less likely to be exposed to the virus.

Migrant workers gather outside Dharavi slums to board a bus during a nationwide lockdown on May 12, 2020.

The level of immunity needed in a population depends on the disease. Scientists don’t yet know what proportion of a population needs to be immune to achieve herd immunity for the novel coronavirus.

Currently, scientists believe that each person infected with coronavirus infects between 2 to 2.5 people, according to the World Health Organization. But that number can be affected by other measures — a lockdown, for instance, could bring down the number of people that each person with coronavirus infects.
It’s hard to know what the threshold is for herd immunity. Initially, some estimates put the figure at 70% to 90%. Adam Kleczkowski, a professor in mathematics and statistics at the University of Strathclyde, Glasgow, calculates it at 50% to 75%, based on what scientists know about how the virus transmits.
With measles, for instance, researchers at the start of the 20th century noticed that infections declined when 68% of children had immunity. But Dowdy points out that measles outbreaks in areas where people are opting not to get vaccinated against measles shows how immunity can be lost.

Building up the level of immunity in a population can happen in two ways. People can become immune by being vaccinated, or they catch the virus and develop natural immunity by recovering from it.

And that’s where things get controversial.

Medical volunteers wearing PPE gear take temperature reading of a woman as they conduct a door-to-door medical screening inside Dharavi slums in Mumbai on July 9, 2020.
The United Kingdom initially said that it would allow the spread of coronavirus within the country to build up to herd immunity. That approach came under fire, with critics warning that it would come at a heavy price: overburdened health systems and unnecessarily high death tolls. The UK — which backtracked on its herd immunity strategy — now has more confirmed coronavirus deaths than most countries. Of the 20 countries most affected by coronavirus, the UK has the highest mortality rate, with 69.63 deaths per 100,000 compared to the US’ 52.28, according to data from Johns Hopkins University.

Most other countries — including India — have taken a different approach. “Herd immunity in a country with the size of population of India cannot be a strategic choice, it can only be an outcome and that, too, at a very high cost,” said the health official, Bhushan.

As Dowdy puts it: “We could very rapidly develop a population immunity to the coronavirus simply by exposing every single person in the population to the disease … it’s just that millions and millions of people are going to die in the process.”

A medical personnel collects a blood sample from a man in India.

Can we build natural immunity?

The science around immunity to Covid-19 is still developing.

A paper released last month — which has not yet been published in a peer-reviewed medical journal — found that antibody responses may start to decline 20 to 30 days after Covid-19 symptoms emerge.

The fact that antibody levels decline over time doesn’t necessarily mean that immunity doesn’t last, Dowdy says. In other viruses, antibody levels decline over time, too, but the immune response is still able to ramp up again if a person is re-exposed to the virus.

According to Dowdy, our immunity to other coronaviruses tends to last a few years, rather than being life-long. “If those are a guide, then that’s what we might expect from this new coronavirus,” he said. “But it’s hard to say. We don’t have any data on this particular virus.”

Antibodies are only one part of the body’s immune system — there are also T cells, which help protect the body from infection, and B cells, which produce the antibodies.
“It is a well co-ordinated orchestra,” said Anthony Tanoto, a senior research fellow at Duke-NUS Medical School in Singapore, who worked on research into T cells in Covid-19 patients.
In a paper published in science journal Nature in July, Tanoto and his co-authors found evidence of T cells from people who had recovered from SARS –– a coronavirus which spread in 2003 — indicating that the cells can last for at least 17 years.
The common cold is a coronavirus and scientists believe that almost everyone has been infected with a coronavirus in their lifetime. That could mean that many people have T cells that might respond to Covid-19.

But for now, Tanoto says we don’t know how much — if at all — these T cells are helping fight off Covid.

In reality, once there is herd immunity — whether naturally or through vaccines — it probably won’t be the impenetrable shield some people might imagine.

Tanoto’s co-author Nina Le Bert, a senior research fellow at Duke-NUS Medical School in Singapore, points out that it’s rare to have complete immunity from infection. Instead, immunity often means that a person’s body is able to respond fast enough to the virus so that it doesn’t gain a foothold — and doesn’t develop enough to infect other people.

“That will be good enough, but that doesn’t mean you don’t get infected,” Le Bert said.

What does this mean for herd immunity?

Even if certain areas do achieve herd immunity, it might not last.

The virus could mutate, meaning people who previously had immunity are no longer immune to the new version of the virus, or a person’s immunity to the virus might not last long, according to Kleczkowski, from the University of Strathclyde.

“Even if we reach herd immunity at some point in time, we might lose it again,” he said. “I don’t think it’s a silver bullet.”

Dowdy says that herd immunity “isn’t a magic number” to solve coronavirus.

“It doesn’t mean that the disease is going to go away. It means that if you gave it 1,000 years, it would go away.”

And he notes that how long herd immunity lasts — whether it’s in a slum or a whole country — partly depends on how much movement there is in and out of that population. If people without immunity come into the area, that lowers the population’s overall level of immunity. If enough people come in, that could mean that there are enough people without immunity for the virus to spread again.

In a Mumbai slum, for instance, people are likely to be coming and going, which could impact how long herd immunity — if there is any — lasts. Utture Shankar, the president of the Maharashtra Medical Council, said people outside slum areas were dependent on those living in slums for services such as gardening, cleaning and driving, so will be exposed beyond their residential community.

In 10 years’ time, Kleczkowski expects that some places in the world will still have coronavirus. Even if there is herd immunity in some places, there may still be an issue with the virus resurfacing, especially if people refuse to get vaccinated.
He points out that, although humans have had vaccines for 200 years, we have only successfully eradicated one disease affecting humans — small pox, thanks to a global vaccination program led by the World Health Organization. But it took a long time. A vaccine was discovered in the late 18th century, but smallpox was only officially declared eradicated in 1979.

When it comes to coronavirus, vaccines are the key to herd immunity — and controlling the virus, Dowdy says.

“I think this is a disease that’s going to be with us for a while,” he said. “But I don’t think it’s going to be a disease that causes the same level of deaths and suffering as it is right now.”

CNN’s Esha Mitra contributed to this story from New Delhi.

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Kim Jong-un ‘apologises for killing of South Korean official’

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Mr Kim said the incident should never have happened

North Korea’s leader Kim Jong-un has issued a rare personal apology for the killing of a South Korean official, Seoul says.

Mr Kim reportedly told his South Korean counterpart Moon Jae-in that the “disgraceful affair” should not have happened.

South Korea has said the 47-year-old man was found by troops floating in the North’s waters.

He was then shot dead and his body was set alight, according to Seoul.

The killing – the first of a South Korean citizen by North Korean forces for a decade – has caused outrage in the South.

The border between the Koreas is tightly policed, and the North is thought to have a “shoot-to-kill” policy in place to prevent coronavirus from entering the country.

What did Kim say in his apology?

The apology came in the form of a letter sent to President Moon which acknowledged that the incident should not have happened, according to South Korea’s Blue House.

Mr Kim called it a “disgraceful affair” and said he felt “very sorry” for “disappointing” Mr Moon and the South Korean people, the Blue House said. It is the North’s first official comment on the incident.

The North also gave the South the results of its investigation – it said more than 10 shots were fired at the man, who had entered North Korean waters and then failed to reveal his identity and tried to flee, South Korea’s director of national security Suh Hoon said.

However the North insisted that it had not burned the man’s body but rather the “floating material” that was carrying him.

“The troops could not locate the unidentified trespasser during a search after firing the shots, and burned the device under national emergency disease prevention measures,” Mr Suh told a briefing, referring to the letter.

What happened to the man?

The father-of-two, who worked for the fisheries department, was on his patrol boat about 10km (6 miles) from the border with the North, near the island of Yeonpyeong, when he disappeared on Monday, the South Korean defence ministry said.

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The South Korean island of Yeonpyeong sits near the border with the North

He had left his shoes behind on the boat. South Korean media said he had recently divorced and had financial problems.

A North Korean patrol boat found the man, who was wearing a life jacket, at sea at around 15:30 local time on Tuesday.

They put gas masks on and questioned him from a distance before “orders from [a] superior authority” came in that the man be killed. He was shot dead in the water.

South Korea says North Korean troops then burned the corpse at sea.

What has the reaction been in the South?

President Moon Jae-in called the killing a “shocking” incident that could not be tolerated. He urged the North to take “responsible” measures over the attack.

The country’s National Security Council said the North could “not justify shooting and burning the corpse of our unarmed citizen who showed no sign of resistance”.

Officials said they had done a “thorough analysis of diverse intelligence”, but it was not clear how exactly they had gathered the information.

The military hotline between North and South was cut in June, and the inter-Korean liaison office, which was built to help both sides communicate, was destroyed by North Korea. But South Korean military is known to intercept the North’s radio communications, AFP news agency reports.

What is the background?

Mr Kim’s apology comes at a time when relations between the North and South are at a low point and there is a stand-off between Pyongyang and Washington over the North’s nuclear programme.

South Korea has in the past demanded apologies from the North but these have rarely been forthcoming. The North has refused to apologise for the sinking of a South Korean warship in 2010, in which 46 sailors died, and denies responsibility. It also refused to apologise for shelling a South Korean island the same year, killing two soldiers and two construction workers.

North Korea may be taking extra-tough measures to prevent the coronavirus from entering the country because it is thought to be preparing for a huge military parade on 10 October to mark the 75th anniversary of the foundation of the ruling Workers’ Party.

Pyongyang closed its border with China in January to try to prevent the spread Covid-19. In July, North Korean state media said the country had raised its state of emergency to the maximum level.

Last month, the commander of the US military’s forces in South Korea, Robert Abrams, said the North had introduced a new “buffer zone” of one to two kilometres on the Chinese border, and that the country had special operation forces in place with orders to “shoot-to-kill” anyone coming across the border.

In the past, North Korea has also returned people who have wandered into their territory. In 2017, state news agency KCNA said officials would repatriate a South Korean fishing boat which “illegally” crossed the border, in what was seen as a rare humanitarian move.

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Mongolia’s most eligible eagle hunter

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(CNN) — “Look over there. See that man coming this way?” asks Timur. “He’s so good looking.”

Galloping towards us on a stout Mongolian steed is the nomad’s version of Brad Pitt returning home in “Legends of the Fall.” Bundled inside a pinto jacket above richly embroidered trousers, he certainly catches the eye. A fox fur hat warms his head, and perched calmly on his right forearm is a golden eagle that’s not merely a prop for a cheesy cologne advertisement.

“Look at his eyebrows and his cheekbones,” continues our Intrepid Travel guide. “And look at how big and strong he is. The girls go crazy over him.”

“It’s true,” says Timur’s wife, Bata, blushing slightly. “If I was to compare him with Timur just on looks, of course I would choose him.”

Upon closer inspection, the intruder’s weathered face betrays a life lived outdoors. But his jaw is certainly chiseled and his natural squint reminds me of a youthful Clint Eastwood as he gazes off into the distance.

Jenisbek Tserik, whose name means “steel warrior,” is a semi-nomadic Kazakh.

Mark Daffey

Arguably more impressive though is his stature, which I only begin to appreciate once he stands beside four other berkutchi, or eagle hunters, who have assembled in front of us for a scheduled photo shoot and interview session. He’s close to a head taller, with broad, square shoulders and muscular limbs that are further exaggerated by his bulky attire.

His name is Jenisbek Tserik, an appellation that means “steel warrior” — an apt description given his achievements. A master horseman, he’s also a serial winner of tug-of-war competitions pitting two combatants wrestling a goat carcass.

So adept is Jenisbek that he has been flown to Dubai to compete in exhibition events. For a semi-nomadic Kazakh living in Mongolia’s remote, westernmost province of Bayan-Ölgii, any trip abroad would be like visiting another planet. Glitzy Dubai would be a whole different universe.

Aged 26, Jenisbek tells us he’s not married, then jokes that he has five girlfriends, including one in Dubai and another in Kazakhstan, from where 90% of Bayan-Ölgii’s resident population originates. I’m unsure if he’s serious, but from what Timur and Bata have told me about him, it’s not beyond the realms of possibility.

As well as the tug-of-war, Jenisbek is a champion archer, and he’s won numerous awards for eagle hunting in Bayan-Ölgii, where the centuries-old pastime is more widespread than anywhere else on the planet.

A proud history

Aged 26, Jenisbek says he's not married -- but has five girlfriends.

Aged 26, Jenisbek says he’s not married — but has five girlfriends.

Tuul & Bruno Morandi/The Image Bank RF/Getty Images

Eagle hunting can be traced back to a forgotten kingdom in Central Asia, where direct descendants of Genghis Khan settled by the Aral Sea until encroaching Russian Empire forces compelled them to flee to the lawless region of the Altai Mountains in Mongolia.

Then, when the Soviet Union and China established borders either side of them early in the 20th century, the Kazakhs became cut off from their homeland and were unable to return.

They continued to live as semi-nomadic herders in Western Mongolia, where traditional pastimes such as hunting with golden eagles continued, passing from one generation to the next. Since such practices were suppressed in Kazakhstan during Soviet rule, Bayan-Ölgii became the sport’s nucleus.

“For a Mongol, it’s pride thing to train racehorses. For Kazakhs, their pride is in training eagles to hunt,” explains Bata.

You can see it in the way they walk and how they behave. The five berkutchi know they’re being watched and they play up to it, puffing their chests out and stiffening their backs whenever a camera lens points their way. Brows furrow and lips purse like they’ve been modeling all their lives.

It’s a far cry from how life must have been in this part of the world before tourism impinged following the first Golden Eagle Festival, which was staged outside the provincial capital of Ölgii in 1999. But even now, foreigners are hardly stampeding to get here. When I quiz our local facilitator about numbers visiting the region this season, he replies that there are “many.”

“How many?” I ask.

“About 800.”

From October to March, eagle hunters head off into the mountains in pairs -- one to flush out their prey, the other to release the eagle from high along a ridgeline.

From October to March, eagle hunters head off into the mountains in pairs — one to flush out their prey, the other to release the eagle from high along a ridgeline.

Mark Daffey

Numbers peak around the timing of the festival in early October, and during the smaller scale Altai Kazakh Eagle Festival, held here in Sagsai two weeks earlier. In each, as many as 100 berkutchi test their skills in events where eagles are expected to catch fox skins being dragged behind horses or in races to scoop up a coin off the ground on horseback.

One flirtatious contest involves a whip-cracking woman chasing after a man who doesn’t always try overly hard to escape. I could imagine Jenisbek receiving a disproportionate share of lashings these past few years.

But it’s only once the tourists have gone that the eagle hunting season begins. From October to March, hunters head off into the mountains in pairs — one to flush out their prey, the other to release the eagle from high along a ridgeline.

Prize catches includes foxes and hares, whose luxuriant coats make the warmest hats, just like those crowning Jenisbek and his companions.

Hunts can last for days at a time, and training requires patience as the eagles become accustomed to their handlers and develop the required skills.

Has it caused couples to divorce, I ask Timur, when husbands spend more time with their birds than they do with their wife? He shrugs his shoulders.

When every unmarried woman in the valley is lining up for you, like they are for Jenisbek, who needs a wife?

Getting there: Though Mongolia is currently closed to tourism due to the Covid-19 pandemic, a number of tour companies are now accepting bookings for for the 2021 Golden Eagle Festival in Bayan-Ulgii, which takes place in early October.

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Pelosi urges voting to counter Trump on peaceful election transition


Speaker Nancy Pelosi said Thursday that President Donald Trump’s refusal to guarantee a peaceful transfer of power if he loses the election could be cured at the ballot box.

“That the president of the United States would place in doubt the idea of the peaceful transfer of power, well it’s not a surprise,” Pelosi said. But a clear result from voters, she said, would be the “antidote” to any doubts raised by Trump in his comments. “I have confidence in the American people,” she said.

Pelosi’s remarks came as congressional Republicans declined to directly confront Trump’s comments but emphatically rejected the notion that the country would see anything but a peaceful transition of power should Democratic presidential nominee Joe Biden win the election. Trump, though, has spent months criticizing the integrity of the election rooted in baseless claims about foreign meddling with mail-in ballots and rampant voter fraud in Democrat-led states.

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