WHO says herd immunity idea is scientifically problematic, not an option

Agencies
October 13, 2020

New Delhi, Oct 13: The World Health Organization has debunked the idea of herd immunity, saying it is 'scientifically and ethically problematic' and is not an option.

There are some who say the coronavirus be allowed to spread naturally in the lack of a vaccine to achieve immunity in a community.

Herd immunity is achieved by protecting people from a virus not by exposing them to it, said WHO Director General Tedros Ghbreseysus.

"Allowing a dangerous virus that we don't fully understand to run free is unethical. It is not a option," Tedros said in a statement on Monday.

Medical journal Lancet also warned that exposure to the virus does not guarantee future immunity. The second infection may come with more severe symptoms.

The Covid-19 virus has claimed one million lives and still spreading across the world. And there is no vaccine available right now.

Tedros made the comments in the context of China which is preparing to test an entire population of the eastern city Qingdao this week.

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Agencies
October 13,2020

New Delhi, Oct 13: The World Health Organization has debunked the idea of herd immunity, saying it is 'scientifically and ethically problematic' and is not an option.

There are some who say the coronavirus be allowed to spread naturally in the lack of a vaccine to achieve immunity in a community.

Herd immunity is achieved by protecting people from a virus not by exposing them to it, said WHO Director General Tedros Ghbreseysus.

"Allowing a dangerous virus that we don't fully understand to run free is unethical. It is not a option," Tedros said in a statement on Monday.

Medical journal Lancet also warned that exposure to the virus does not guarantee future immunity. The second infection may come with more severe symptoms.

The Covid-19 virus has claimed one million lives and still spreading across the world. And there is no vaccine available right now.

Tedros made the comments in the context of China which is preparing to test an entire population of the eastern city Qingdao this week.

Comments

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Agencies
October 15,2020

While transmission of the novel coronavirus as small aerosol particles is more significant in summer, direct contact with respiratory droplets may be more pronounced in the winter months, according to a new research.

The modelling study, published in the journal Nano Letters, also noted that the currently followed physical distancing guidelines are inadequate in curbing the transmission of COVID-19.

"We found that in most situations, respiratory droplets travel longer distances than the 6-foot social distance recommended by the CDC," said Yanying Zhu, a co-author of the study from the University of California (UC) Santa Barbara in the US.

In indoor environments such as walk-in refrigerators and coolers, where temperatures are low and humidity is high to keep fresh meat and produce from losing water in storage, the scientists said this effect is increased with the droplets transmitting to distances of up to 6 metres (19.7 feet) before falling to the ground.

They said in such environments, the virus is particularly persistent, remaining "infectious from several minutes to longer than a day in various environments."

"This is maybe an explanation for those super-spreading events that have been reported at multiple meat processing plants," Zhu said.

At the opposite extreme, in hot and dry places, the researchers said respiratory droplets more easily evaporate.

In such conditions, they said the evaporated droplets leave behind tiny virus fragments that join the other aerosolised virus particles that are shed as part of speaking, coughing, sneezing and breathing.

"These are very tiny particles, usually smaller than 10 microns. And they can suspend in the air for hours, so people can take in those particles by simply breathing," said study lead author Lei Zhao.

In summer, the scientists said aerosol transmission may be more significant compared to droplet contact, while in winter, droplet contact may be more dangerous.

"This means that depending on the local environment, people may need to adopt different adaptive measures to prevent the transmission of this disease," Zhao said.

The scientists recommended greater social distancing if the room is cool and humid, and finer masks and air filters during hot, dry spells.

According to the researchers, hot and humid environments, and cold and dry ones, did not differ significantly between aerosol and droplet distribution.

They believe the findings could serve as useful guidance for public health decision-makers in efforts to keep the COVID-19 spread to a minimum.

"Combined with our study, we think we can maybe provide design guidelines for the optimal filtering for facial masks," Zhao said.

He added that the research could be used to quantify real exposure to the virus -- how much virus could land on one's body over a certain period of exposure.

According to the scientists, the insights, "may shed light on the course of development of the current pandemic, when combined with systematic epidemiological studies."

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Agencies
October 11,2020

The Covid-19 vaccines closest to the finish line are designed to be injected into the arm. Researchers are looking at whether they can get better protection from inoculations that fight the virus at its point of attack — the nose and mouth.

Most vaccines in human testing require two shots for effectiveness, and developers still aren’t even sure if they’ll prevent infections. Scientists are hoping to generate superior immune responses with inhaled vaccines that directly target the airway cells the virus invades.

An alternative to conventional jabs, sprayed and inhaled immunizations under development in the U.S., Britain and Hong Kong could play an important role in helping society escape restrictions that have upended economies and everyday life. Among their goals is to prevent the pathogen from growing in the nose, a point from which it can spread to the rest of the body, and to other people.

“Local immunity matters,” said Frances Lund, a University of Alabama at Birmingham immunologist working with biotech Altimmune Inc. on an early-stage nasal inoculation. “The vaccines that can be delivered to generate that will have some advantages over vaccines that are delivered systemically.”

Most early vaccine developers focused on a familiar route — injections — seen as the fastest to protecting the world from disease. Inhaled vaccine makers are counting on some of the unique features of the lungs, nose and throat, which are lined with mucosa. This tissue contains high levels of immune proteins, called IgA, that give better protection against respiratory viruses.

Activating these immune weapons, they theorize, can protect areas deeper in the lungs where the SARS-CoV-2 does the most damage. They also may improve vaccines’ chances of blocking transmission.

“The first generation of vaccines are probably going to protect a lot of people,” said Michael Diamond, an infectious disease specialist at Washington University in St. Louis. “But I think it’s the second- and third-generation vaccines — and maybe intranasal vaccines will be a key component of this — that ultimately are going to be necessary. Otherwise, we’ll continue to have community transmission.”

In a study of mice in August, Diamond and his team found that delivering an experimental vaccine via the nose created a strong immune response throughout the body; the approach was especially effective in the nose and respiratory tract, preventing infection from taking hold. India’s Bharat Biotech and St. Louis-based Precision Virologics last month obtained rights to the single-dose technology.

Vaccines that are sprayed into the nose or inhaled may hold other practical benefits. They don’t require needles, may not need to be stored and shipped at low temperatures and can reduce the need for health workers to administer them.

“When you’re thinking about trying to deliver that across the world, if you don’t need to have an injectable vaccine, your compliance goes up because people don’t like getting shots,” according to Lund, the Alabama-based researcher. “But secondly, the level of expertise needed to administer that vaccine is significantly different.”

Altimmune, based in Gaithersburg, Maryland, plans to enter human testing with a nasal vaccine in the fourth quarter after positive studies in mice. Scientists at the University of Oxford, where a promising shot under development at AstraZeneca Plc was designed, and Imperial College London are also planning studies of slightly different inhaled vaccines.

The experimental immunizations in Britain would be delivered through a mouthpiece in an aerosol, similar to some asthma therapies. Imperial researchers point to evidence that delivering influenza vaccines via a nasal spray can protect people against illness and help reduce transmission; they’re keen to explore if that’s also the case for SARS-CoV-2. AstraZeneca makes the FluMist nasal spray vaccine.

Data from studies of the inhaled Oxford vaccine could come early in the new year, followed by Imperial results in the second quarter, according to Robin Shattock, an infectious disease specialist at Imperial College.

“We don’t know whether it will work well, but if it does, then it could be very important,” he said in an interview.

Imperial College in recent months has been advancing studies of a Covid vaccine using RNA technology that would be delivered via conventional shots and plans to expand its trials to 20,000 people by year-end. Oxford, one of the front-runners in the global quest for an inoculation, is in the final stage of tests for a shot that uses a harmless virus to carry the genetic material of the pathogen into cells to generate an immune response. Both techniques may be conducive to inhalation, Shattock said.

“This is a virus that’s transmitted through your respiratory tract, so if you want a vaccine that will really prevent infection and onward transmission you want to have an antibody response in your nose, in your lungs,” Shattock said. “The most efficient way to induce that is by inoculating through that route.”

Researchers in Hong Kong are aiming for an intranasal vaccine that would simultaneously offer influenza and Covid-19 protection. The first phase of human tests will start next month, said Yuen Kwok-Yung, chair of infectious diseases in the University of Hong Kong’s department of microbiology.

The ambition is to come up with the “vaccine of choice,” as the world looks to build on the first wave of products, he said.

Questions about the durability of nasal vaccines have yet to be resolved, and they’re at an early stage. Despite the advantages, the delivery devices are also more complex, according to Nick Jackson, head of programs and technology at the Coalition for Epidemic Preparedness Innovations.

“A needle and syringe work very well,” he said.

Still, researchers said targeting the airways may pay off down the road. Oslo-based CEPI has provided funding to the Hong Kong project and is open to further investments in vaccines that are taking unconventional approaches as part of an effort to supply billions of doses to every corner of the world, Jackson said.

“Whether it’s our vaccine or another one that goes through an intransasal route that actually is successful at disrupting transmission and disrupting the pandemic, I take my hat off,” Diamond said. “If we contribute by compelling or nudging these companies to think about an alternative route for what may be a successful platform, then we’ve done our job.”

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