How airflow inside car may affect coronavirus transmission risk decoded

News Network
December 5, 2020

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Boston, Dec 5: Using computer simulations, scientists have analysed the airflow patterns inside a car's passenger cabin, shedding light on the potential ways to reduce the risk of Covid-19 transmission while sharing rides with others.

The study, published in the journal Science Advances, assessed the airflow inside a compact car with various combinations of windows open or closed.

According to the researchers, including those from Brown University in the US, the simulations showed that opening windows created airflow patterns that dramatically reduced the concentration of airborne aerosol particles exchanged between a driver and a single passenger.

However, they said blasting the car's ventilation system didn't circulate air nearly as well as a few open windows.

"Driving around with the windows up and the air conditioning or heat on is definitely the worst scenario, according to our computer simulations," said Asimanshu Das, co-lead author of the research from Brown University.

"The best scenario we found was having all four windows open, but even having one or two open was far better than having them all closed," Das said.

While there's no way to eliminate risk completely, and current guidelines recommend postponing travel, the scientists said the goal of the study was simply to assess how changes in airflow inside a car may worsen or reduce risk of Covid-19 transmission.

In the research, the computer models simulated a car, loosely based on a Toyota Prius, with two people inside -- a driver, and a passenger sitting in the back seat on the opposite side from the driver.

The scientists said they chose this seating arrangement since it maximised the physical distance between the two people.

Since the novel coronavirus is thought to spread via tiny aerosol particles that can linger in the air for extended periods of time, the researchers simulated airflow around and inside a car moving at 50 miles per hour.

Part of the reason opening windows is better in terms of aerosol transmission is because it increases the number of air changes per hour (ACH) inside the car that reduces the overall concentration of aerosols, the study noted.

The scientists showed that different combinations of open windows created different air currents inside the car that could either increase or decrease exposure to remaining aerosols.

Since the occupants in the simulations were sitting on opposite sides of the cabin, they said very few particles ended up being transferred between the two.

According to the research, the driver was at slightly higher risk than the passenger since the average airflow in the car goes from back to front, but added that both occupants experience a dramatically lower transfer of particles.

When some -- but not all -- windows were down, the study yielded counterintuitive results.

Citing an example of one such instance, the scientists said opening the windows next to each occupant carried a higher exposure risk, compared to putting down the window opposite each occupant.

"When the windows opposite the occupants are open, you get a flow that enters the car behind the driver, sweeps across the cabin behind the passenger and then goes out the passenger-side front window," said Kenny Breuer, a professor of engineering at Brown University and a senior author of the research.

"That pattern helps to reduce cross-contamination between the driver and passenger," Breuer said.

The scientists said airflow adjustments are no substitute for mask-wearing by both occupants when inside a car, adding that the findings are limited to potential exposure to lingering aerosols that may contain pathogens.

Citing another limitation of the study, the scientists said it did not model larger respiratory droplets or the risk of actually becoming infected by the virus.

However, they said the findings provide valuable new insights into air circulation patterns inside a car's passenger compartment.

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Agencies
January 12,2021

New Delhi, Jan 12: Amid the ongoing debate around the safety and efficacy aspects of Covid vaccines, the president of Indian Medical Association (IMA) has advised the public to not worry too much about it.

Speaking to IANS, Dr. J.A. Jayalal, president, IMA said, "We should not be too worried about the safety and efficacy of the vaccines since enough evidence is available to prove its credibility.

"The vaccines are never 100 per cent protective and efficacious at any time. It helps us to some extent in getting ahead of the disease but eventually, herd immunity will set in to control the viral spread. So let's not worry too much about the safety and efficacy part," he said.

"What we know from the trials is that the vaccines approved for inoculation in India are found safe and elicit an immune response. The technology of harnessing vaccines from inactivated viruses is a proven science. Our least expected efficacy criteria is 50 per cent while at the same time, other drugs we have been using for years are even below this benchmark of efficacy. We use influenza and vaccines against Tuberculosis but still people contract it," Jayalal explained.

"Even natural infection cannot determine the level of antibodies it would create in the body. Some may develop less antibodies, some may exhibit high titers of it while a few may never develop at all. Good thing is that the vaccines are producing antibodies and it's enough at this stage," he added.

Jayalal also said that the vaccine would work against the current and mutant strains of the coronavirus. Such claim was earlier made by Bharat Biotech for its Covid vaccine, Covaxin, which is approved for restricted emergency use in a clinical trial mode'. However, the firm is yet to present the data confirming its claim.

The apex association of modern medicine practitioners in the country has come out publicly endorsing the safety and efficacy of Covid-19 vaccines. In a statement issued on Monday, it said that the association stands with the scientists to endorse the safety and efficacy of both Covaxin and Covishield for public awareness and to counter myths on vaccine percolating in social media.

The IMA has also appealed to its its 3.5 lakh members in 1,800 local branches to actively take part in the mission of Covid vaccination programme rolled out by the Government of India. "Come out to get vaccinated first to show to the world that these vaccines are safe and efficacious," it had said.

Despite the efficacy of both the vaccines still unknown, the IMA has endorsed the vaccines. When asked about it, Jayalal said the association had a detailed discussion on such aspects with the government agencies. "After analyzing all the scientific data, we have decided to come out firmly in support of the vaccines," he added.

India's drug regulator has approved two Covid vaccine candidates -- Covishield by Serum Institute of India and Covaxin by Bharat Biotech -- for the massive inoculation drive against the Covid-19.

The immunization drive will start from January 16. The vaccines have already reached many of the primary hubs to be distributed further before the roll-out.

Till now, a total 1,51,327 people have succumbed to the deadly disease while it has infected 1,04,79,179 people in the country.

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Agencies
January 6,2021

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Geneva, Jan 6: The 'UK' coronavirus variant had been detected in 41 countries/territories, the World Health Organization (WHO) said in a statement.

"As of 5 January 2021, the VOC-202012/01 variant initially detected in the United Kingdom has been detected in a small number of cases in 40 other countries/territories/areas in five of the six WHO regions, and the 501Y.V2 variant initially detected in South African in six other countries/territories/areas," the WHO said.

On December 14, 2020, the UK announced that a new coronavirus strain had been detected in the country, with the new variant being 70 per cent more transmissible.

After the news emerged, many countries suspended travel to and from the UK.

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Agencies
January 18,2021

Global gaps in access to Covid-19 vaccines are raising concerns that the continued spread of the coronavirus will breed more dangerous versions of the pathogen, weakening medical weapons and further crippling economies.

In a race to catch up with emerging coronavirus variants, wealthy countries are already benefiting from potent vaccines. While the US, Britain and European Union have given citizens about 24 million doses so far -- more than half of the shots administered globally -- vast numbers of countries have yet to begin their campaigns.

Disparities in immunity pose a threat to both have and have-not states. Giving the coronavirus an opportunity to advance and generate new mutants would have significant economic and public-health consequences, adding to the pain as the death toll surpasses 2 million.

Growth forecast

“We cannot leave parts of the world without access to vaccines because it’s just going to come back to us,” said Charlie Weller, head of vaccines at health research foundation Wellcome. “That puts everyone around the world at risk.”

Countries are relying on effective immunisations to save lives and revive businesses. The World Bank’s projection for 4 per cent growth this year depends on the widespread deployment of vaccines. Surging Covid cases and a delay to the delivery of inoculations, however, could limit expansion to just 1.6 per cent.

High-income countries have secured 85 per cent of Pfizer Inc.’s vaccine and all of Moderna Inc.’s, according to London-based research firm Airfinity Ltd. Much of the world will be counting on UK drugmaker AstraZeneca Plc, whose vaccine is cheaper and easier to distribute, along with other manufacturers such as China’s Sinovac Biotech Ltd.

Of 42 countries rolling out Covid vaccines as of Jan. 8, 36 were high-income countries and the rest were middle-income, according to World Health Organization Director-General Tedros Adhanom Ghebreyesus. A growing number of countries are pursuing their own supply deals, in addition to participating in a global collaboration known as Covax.

Future mutants

Urgency is increasing as the pandemic extends into a second year. New variants that surfaced in the UK, South Africa and Brazil appear to spread significantly faster than earlier versions. Just in the past month, a “new dimension of risk has opened up for the world,” said Rajeev Venkayya, president of Takeda Pharmaceutical Co.’s vaccines business.

Reducing deaths and illnesses has been seen as the main driver of delivering vaccines rapidly, said Venkayya, who worked in the George W. Bush administration to develop a U.S. pandemic flu plan and directed vaccine delivery for the Gates Foundation.

“We now understand it’s also very, very important to control transmission,” he said, “not just to protect those most vulnerable populations, but also to reduce the evolutionary risk associated with this virus.”

While there’s no evidence to suggest the current crop of vaccines are ineffective against those variants, future mutants may be less responsive, Wellcome’s Weller said.

Drugmakers say they could tweak their shots to counter new variants within weeks if needed. The likelihood that such adaptations will be necessary has increased, Venkayya said.

“The longer the virus is allowed to continue in different parts of the world where we don’t have a vaccine,” said Anna Marriott, health policy adviser at the anti-poverty group Oxfam, “the greater the danger of new variants that could be more aggressive, more virulent or transmissible.”

Covid shots have been tested for their ability to prevent symptoms, not the transmission. Still, their performance in clinical trials gives an indication of how effective they might be against the spread.

Effectiveness gap

The rollout of shots from Pfizer-BioNTech SE and Moderna that achieved efficacy levels of about 95% has raised questions about whether everyone will have access to such high levels of protection.

“The gap isn’t just about access to vaccines,” said Yanzhong Huang, senior fellow for global health at the Council on Foreign Relations. “It’s also about access to effective vaccines.”

One of the shots lower- and middle-income countries are relying on, from AstraZeneca and the University of Oxford, sparked worries in Australia that it may not be effective enough to generate herd immunity. Health authorities there, however, said they believe it will be comparable to the Pfizer and Moderna shots in preventing people from getting seriously ill.

The vaccine developed by the U.K. partners, introduced in the country earlier this month, delivered an average efficacy rate of 70%. That appeared to climb to 80% with a longer gap between doses, based on limited data available, according to regulators. Lengthening that period to as many as three months from one allows more people to get protected faster, while data show the level of antibodies also increases, an AstraZeneca spokesman said.

“An optimized regimen which allows the vaccination of many more people upfront, together with a robust supply chain, means we can have a real impact on the pandemic,” he said in an email.

Four vastly differing protection rates have been released on Sinovac’s shot, ranging from about 50 per cent to more than 90 per cent. The Chinese developer said the lower number seen in a trial in Brazil is due to participants being medical workers facing a high risk of contracting Covid.

“Despite the difference in efficacy rate, they all point to the vaccine’s ability for protection, especially against mid- and severe disease,” Sinovac said.

While the picture is still coming into focus, cleared vaccines are likely to be similarly effective in preventing serious sickness and death, said Takeda’s Venkayya. Where they could diverge is on side effects, the duration of protection and impact on transmission, an even more critical factor in light of new variants, he said.

Even shots with a lower efficacy level could have a considerable impact. US regulators set a 50 per cent threshold for deeming a candidate effective. But they would require a higher percentage of people willing to get vaccinated to achieve herd immunity, Huang said.

If less-effective vaccines are distributed to emerging markets, it could have significant economic implications, too, and “sharpen differences in pandemic outcomes across countries,” Justin-Damien Guenette, a senior economist at the World Bank, wrote in an email.

Many countries are depending on Covax, which aims to deploy vaccines equitably to every corner of the planet. Yet not all lower- and middle-income nations are waiting for a lifeline. Countries such as South Africa and Malaysia are also pursuing their own supply deals through direct talks with manufacturers, and some regions are set to receive Pfizer’s vaccine as well.

‘Losing patience’

“There seem to be indications that countries are losing patience,” said Huang of the Council on Foreign Relations.

Covax has secured access to almost 2 billion doses, with deliveries due to begin in the first quarter, and set a goal of vaccinating up to a fifth of countries’ populations by the end of the year. That’s far short of the levels of two-thirds or more that many nations are targeting. Some may not get vaccines until 2024, researchers estimate.

The mobilization is ramping up. India, a nation of more than 1.3 billion people, kicked off a massive inoculation drive on Saturday, an effort expected to encounter challenges as it extends into rural areas.

Vaccine advocates have called on rich countries to share while pushing companies to scale up manufacturing capacity. While it’s early, the trends are concerning, Venkayya said.

“Success is defined as getting vaccines to people everywhere,” he said, “and we’re not yet successful in that endeavour.”

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