Study supports airborne spread of COVID-19 in indoors

September 30, 2020

A new research adds to the growing body of evidence that airborne transmission of COVID-19 spreads more quickly in enclosed spaces.

Researchers were able to link a community outbreak of COVID-19 in China to a source patient who likely spread the virus to fellow bus riders through the bus's air conditioning system.

"Our study provided epidemiologic evidence of transmission over long distances, which was likely airborne," said study lead author Ye Shen from University of Georgia in the US.

According to the study, published in the journal JAMA Internal Medicine, it was largely believed that close contact through droplets is a major route of transmission for COVID-19.

"However, the widely adopted social distancing and hand washing did not effectively prevent the transmission globally. Instead, the number of new COVID-19 cases increased steadily," said Shen.

The research team worked with epidemiologists from two regional Centers for Disease Control and Prevention in China to trace infections following a large outdoor worship event in Zhejiang province.

Some of the attendees, it turns out, took two buses to the event creating a unique natural experiment for the researchers.

Both buses had closed windows and had air conditioning running, said Changwei Li, study co-author, but one bus carried a patient infected with the virus, and the other did not.

Of the passengers who later got sick, the majority of them rode on the same bus as the source patient.

Even though the two groups later mixed in with the larger crowd at the worship event, the number of new cases attributed to the event were much lower, suggesting that the bus was the major point of transmission.

Further, some of the bus passengers who later showed symptoms of COVID-19, the authors found, were not sitting close to the infected passenger.

These findings highlight scenarios where COVID-19 could be spread through fine aerosol particles being circulated in an enclosed space.

"Understanding the transmission routes of COVID-19 is critical to contain the pandemic, so that effective prevention strategies can be developed targeting all potential transmission routes," said Shen.

"Our findings provide solid support for wearing face covering in enclosed environments with poor ventilation," the study author wrote.

Recently, another study published in the journal Proceedings of the National Academy of Sciences, found that ordinary conversation creates a conical 'jet-like' airflow that quickly carries a spray of tiny droplets from a speaker's mouth across metres of interior space.


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News Network
October 9,2020


Bengaluru, Oct 9: Researchers from the Indian Institute of Science (IISc) said they have developed a non- invasive bandage made with magnetic nanofibres to treat skin cancer by administering heat to the tumour cells.

Skin cancer is caused mainly due to excessive exposure to ultraviolet rays from the sun.

There are two types: Melanoma, which develops from pigment-producing cells in the skin called melanocytes, and non-melanoma, which develops from other skin cells, IISc said.

Though non-melanoma skin cancer is more widespread, melanoma is malignant and has a higher mortality rate, according to Bengaluru-based IISc.

Common treatments for skin cancer include surgery, radiation therapy, and chemotherapy.

But these treatments and other conventional therapies have limitations.

A promising alternative that has emerged to treat skin cancer is hyperthermia, which involves applying heat to the affected tissues.

In recent years, researchers have been working on developing ways of delivering heat to the tumour tissues so that cancer cells are targeted selectively and effectively, IISc noted in a statement on Thursday.

One such technology is called magnetic hyperthermia, in which magnetic nanoparticles are used to heat the tumours by using an external alternating current magnetic field (AMF).

But it is difficult to achieve uniform heating of the affected tissues using such magnetic nanoparticles because of uncontrolled aggregation.

Besides, they can accumulate in the human body and induce toxicity.

Now, researchers from the Centre for BioSystems Science and Engineering (BSSE) and the Department of Molecular Reproduction, Development and Genetics (MRDG) at IISc have developed a bandage with a unique blend of magnetic nanoparticles fabricated using a method called electrospinning.

It comprises nanoparticles made from an oxide of iron, Fe3O4, and a biodegradable polymer called polycaprolactone (PCL) pasted on a surgical tape.

The magnetic material generates heat when it is subjected to a high-frequency oscillating magnetic field.

In order to investigate whether the heat generated and dissipated by the magnetic bandage can treat skin cancer, the researchers did two experiments: One was in vitro on human cancer cell lines and the other was in vivo on mice with artificially-induced skin cancer.

"The protocol used to prepare the PCL-Fe3O4 fibrous mat-based bandage took a little more than two months to optimise; however, the in vitro and in vivo tests that involved the testing of the magnetic thermal therapy took quite some time to optimise," said Kaushik Suneet, a former project associate at BSSE and the first author of the study.

In both experiments, the heat generated by applying AMF to the nanofibrous magnetic bandage killed the cancer cells successfully.

Moreover, in the in vivo experiment, the healthy tissue remained intact with no signs of burns, inflammation, or thickening.

"The elevated temperature at the treatment site enables heat to penetrate the tumour cells, rupturing the compact random vasculatures (network of blood vessels) of the tumours," explained Shilpee Jain, who was a DST-INSPIRE Faculty Fellow at BSSE when the study was conducted, and is a senior author of the paper.

"(In contrast), the normal healthy cells, owing to their organised open vasculatures, dissipate the heat to maintain normal temperatures, and so remain unharmed."

Though this novel treatment has been shown to be effective against skin cancer in lab experiments, it is still at a nascent stage of development as a clinical therapy, the statement said.

"Further studies are required to test the efficacy of this novel treatment method on a larger scale in rabbits, dogs and monkeys before employing it for pre-clinical and clinical applications," cautioned Jain.


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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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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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