Coronavirus may spread more via respiratory droplets in winter: scientists

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 24,2020

Washington, Oct 24: The initial phase of the COVID-19 lockdown, which was imposed through March and April in several countries, may have dramatically altered people's personal eating and sleeping habits, according to a new study based on a first-of-its-kind global survey.

The study, published in the journal Obesity, evaluated the inadvertent changes in health behaviours that took place under the pandemic's widespread restrictions.

According to the survey, conducted by the researchers, including those from Louisiana State University (LSU) in the US, the lockdown's effects were magnified among people with obesity.

"The stay-at-home orders did result in one major health positive. Overall, healthy eating increased because we ate out less frequently. However, we snacked more. We got less exercise. We went to bed later and slept more poorly. Our anxiety levels doubled," said study co-author Leanne Redman from Louisiana State University.

"Overall, people with obesity improved their diets the most. But they also experienced the sharpest declines in mental health and the highest incidence of weight gain," Redman said.

The survey ran during the month of April and included responses from 7,754 people and the majority of the respondents were in the US with residents of Australia, Canada, the UK, and more than 50 other countries also participating.

It revealed that about one-third of surveyed people with obesity gained weight during the lockdown, compared to 20.5 percent of people with normal weight or overweight.

"This study is the first to survey thousands of people across the globe on lifestyle behaviour changes in response to stay-at-home orders. The study demonstrates that chronic diseases like obesity affect our health beyond the physical," said John Kirwan, another co-author of the study.

The scientists believe physicians and scientists should modify the way they manage patients with obesity in two ways.

One of these methods is by increasing the number of mental health screenings during and after the pandemic, said Emily Flanagan, lead author of the study from LSU.

Flanagan said physicians should also monitor patients by remaining connected to the study participants through remote visits and telehealth to prevent irreversible health effects from the pandemic.

The scientists believe virtual visits via telehealth checkups can assuage patients' concerns about the safety of in-person visits.

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Agencies
October 11,2020

Pune, Oct 11: Bharat Biotech, which had sought DCGI's nod for conducting phase-3 clinical trials of its COVID-19 vaccine candidate, has been asked to submit complete safety and immunogenicity data of the ongoing phase-2 trial, besides providing some clarifications, before proceeding for the next stage.

The vaccine candidate -- 'Covaxin' -- is being indigenously developed by the Bharat Biotech in collaboration with the Indian Council of Medical Research (ICMR).

According to officials, the Hyderabad-based vaccine maker applied to the Drugs Controller General of India (DCGI) on October 2, seeking its permission to conduct phase-3 randomised double-blind placebo-controlled multicentre trial of its COVID-19 vaccine candidate.

The firm in its application said that the study would cover 28,500 subjects aged 18 years and above and would be conducted in 19 sites -- including Delhi, Mumbai, Patna and Lucknow -- across 10 states.

According to sources, the phase-2 trial of the Covaxin is going on and the second dose is yet to be given to volunteers at some sites.

"The company presented phase-3 clinical trial protocol along with interim data of phase 1 and 2 clinical trials," an official said.

The subject expert committee (SEC) at the Central Drugs Standard Control Organisation(CDSCO) deliberated on the application on October 5.

"After a detailed deliberation, the committee opined that the design of the phase-3 study is in principle satisfactory except for clarification on definition of asymptomatic, etc.

"However, the study should be initiated with appropriate dose identified from the phase-2 safety and immunogenicity data. Accordingly, the firm should submit safety and immunogenicity data from phase-2 trial for consideration," the panel said in its recommendations.

The SEC during its discussion also observed that the vaccine was well-tolerated in all dose groups and no serious adverse events have been reported so far, a source said.

The most common adverse event was pain at the injection site, which resolved transiently, the source said.

The phase-3 clinical trial application proposed a dose of 0.5 ml on day 0 and 28, sources said.

Besides, Bharat Biotech, indigenously developed vaccine candidate by Zydus Cadila Ltd is in the phase 2 of the human clinical trials.

The Pune-based Serum Institute of India, which has partnered with AstraZeneca for manufacturing the Oxford COVID-19 vaccine candidate, is also conducting Phase 2 and 3 human clinical trials of the candidate in India.

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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.

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