Tag: covid transmission

Categories : COVIDTags :

Sunlight Vulnerability of SARS-CoV-2 not Just from UV-B

On By ModernMedia

A team of researchers have found that the sunlight vulnerability of SARS-CoV-2 cannot be explained by the effect of UV-B rays alone.

Most of the COVID management concepts remain as true as in the first days of the pandemic, such as handwashing with soap and social distancing, though some have changed such as the notion of the virus mainly transmitted through droplets whereas evidence showed it can linger suspended in aerosol.

The researchers, from UC Santa Barbara, Oregon State University, University of Manchester and ETH Zurich. examined the well-known vulnerability of SARS-CoV-2 to sunlight. They concluded that exposure to UV-B radiation doesn’t completely account for its inactivation by sunlight.

The idea that an additional mechanism might be in play came when the team compared data from a July 2020 study that reported rapid sunlight inactivation of SARS-CoV-2 in a lab setting, with a theory of coronavirus inactivation by solar radiation that was published just a month earlier.

“The theory assumes that inactivation works by having UV-B hit the RNA of the virus, damaging it,” said lead author Paolo Luzzatto-Fegiz, UC Santa Barbara mechanical engineering professor. “Judging from the discrepancies between the experimental results and the predictions of the theoretical model, however, the research team felt that RNA inactivation by UV-B “might not be the whole story.”

Experimentation showed 10-20 minutes to reach virus inactivation—much faster than the theory’s predictions. Viruses in simulated saliva were inactivated over eight times faster when irradiated by UV-B lamps than would have been predicted by the theory, while those cultured in a complete growth medium before exposure to UV-B were inactivated over three times faster. In order to match theory, SARS-CoV-2 would then have greater UV-B sensitivity than any currently known virus.

“The theory predicts that inactivation should happen an order of magnitude slower,” Prof Luzzatto-Fegiz said.

There might be another mechanism involved besides UV-B effects on RNA; such as the synergistic effect of the less energetic UV-A rays.

“People think of UV-A as not having much of an effect, but it might be interacting with some of the molecules in the medium,” he said. Such reactive intermediate molecules could be hastening virus inactivation, a concept known in wastewater treatment and other environmental science fields.

“So, scientists don’t yet know what’s going on,” Luzzatto-Fegiz said. “Our analysis points to the need for additional experiments to separately test the effects of specific light wavelengths and medium composition.”

These findings could help develop ways to control the virus with widely available UV-A and UV-B sources. Sources which emit UV-C, which is otherwise blocked by the atmosphere, has proven effective in certain settings such as air filtration but its high energy limits applications and raises safety concerns.

“UV-C is great for hospitals,” said co-author Julie McMurry. “But in other environments—for instance kitchens or subways—UV-C would interact with the particulates to produce harmful ozone.”

Co-author and UCSB mechanical engineering professor Yangying Zhu added that UV-A’s possible effectiveness meant that inexpensive UV-A LEDs many times brighter than UV-A in normal sunlight could be used. UV-A could be used more for air filtration for example, but the specifics of each setting warrant consideration, said co-author Fernando Temprano-Coleto.

Source: Medical Xpress

Journal information: Paolo Luzzatto-Fegiz et al. UVB Radiation Alone May Not Explain Sunlight Inactivation of SARS-CoV-2, The Journal of Infectious Diseases (2021). DOI: 10.1093/infdis/jiab070

Categories : COVID General InterestTags :

CDC Director Fears ‘Impending Doom’ as COVID Cases Rise Again

On By ModernMedia

Rochelle Walensky, MD, the Centers for Disease Control (CDC) Director, says that she fears “impending doom” as COVID deaths in the US edge upwards as people increasingly ignore health restrictions and start to travel.

Beginning her usual COVID status update,  Dr Walensky spoke as she often did of “concerning trends in the data.”

Dr Walensky spoke about the country surpassing 30 million COVID cases; of a 10% increase in the 7-day average of COVID-19 cases over the past week, to slightly below 60 000 cases; and of an uptick in hospitalisations, from a 7-day average of around 4600 per day to around 4800 per day.

“And deaths, which typically lag behind cases and hospitalizations, have now started to rise,” she said, pointing to a nearly 3% increase to a 7-day average of “approximately 1000 deaths per day.”

“I’m going to pause here,” she said. “I’m going to lose the script and I’m going to reflect on the recurring feeling I have of impending doom.”  

At the start of her tenure, Walensky said she had pledged to always tell the truth even if it wasn’t something Americans wanted to hear.

“We have so much to look forward to, so much promise and potential of where we are, and so much reason for hope. But right now I’m scared,” she said.

She recalled her time caring for COVID patients, saying: “I know what it’s like as a physician to stand in that patient room, gowned, gloved, masked, shielded and to be the last person to touch someone else’s loved one because their loved one couldn’t be there.

“I know what it’s like when you’re the physician, when you’re the healthcare provider, and you’re worried that you don’t have the resources to care for the patients in front of you.” 

She also recalled “that feeling of nausea, when you read the ‘Crisis Standards of Care’ and you wonder whether there are going to be enough ventilators to go around and who’s going to make that choice.”

She emphasised that she was speaking “not only as your CDC director, but as a wife, as a mother, as a daughter, to ask you to just please hold on a little while longer.”

She sympathised, she said, with those “wanting to be done” with the pandemic.

“We are just almost there, but not quite yet. And so I’m asking you to just hold on a little longer, to get vaccinated when you can. So that all of those people that we all love will still be here when this pandemic ends.”

Dr Walensky warned that the US pandemic trajectory was looking dangerously similar to that of European countries like Germany that were still struggling to contain the virus.

“We are not powerless. We can change this trajectory of the pandemic,” she said.

“But it will take all of us recommitting to following the public health prevention strategies consistently while we work to get the American public vaccinated.”

According to the New York Times’  COVID vaccination tracker, 146 million vaccinations have been administered in the US to date, with 2.76 million doses being given daily. At this rate, 70% of the adult population will have been vaccinated by June 16.

She urged community and religious leaders, officials, and other influencers to help support the vaccination programme.

“For the health of our country, we must work together now to prevent a fourth surge.”

Source: MedPage Today

Categories : COVIDTags :

Asymptomatic Carriers are the Biggest Barrier to Containing COVID

On By ModernMedia

The lack of testing in asymptomatic carriers makes it harder to control SARS-CoV-2 spread, according to researchers at the Georgetown Center for Global Health Science and Security, Georgetown University in Washington.

Two groups of individuals dominate the transmission of COVID: asymptomatic carriers, who do not develop any symptoms throughout the course of their infection; and presymptomatic carriers, who develop symptoms a few days after being infected.

Transmission without symptoms makes it difficult to estimate the infectious timeline and potential exposures. Asymptomatic cases may likely mingle with others oblivious to their infection, promoting virus spread. They may also not adhere to social distancing, mask wearing etc. Contact tracing is vital to monitor the spread of the disease, and asymptomatic cases makes surveillance to analyse secondary attack rates highly challenging.

Though there is no accurate reporting on the prevalence of asymptomatic cases available, early studies showed that they made up so 30% to 80% of infections. More recent evidence put asymptomatic cases at 17% to 30% of infections.

In COVID cases, the infectious period begins two days before symptom onset and several days thereafter, though viral shedding is reduced in the first week of symptoms.

Viral shedding in asymptomatic cases is poorly understood, however it is known that asymptomatic cases have the same viral load as symptomatic cases, regardless of severity. In asymptomatic individuals, infectious periods are shorter due to reduced titers at peak replication and faster viral clearance.

Some studies have shown that asymptomatic individuals are 42% less likely to infect others and have lower secondary attack rates, while other research indicates that, despite the shorter infectious periods, asymptomatic individuals have similar transmissibility to those who are presymptomatic.
The researchers note that symptomatic individuals were motivated to seek testing, treatment and self-isolate upon feeling COVID symptoms.

“With many contagious people experiencing no symptoms and in the absence of robust surveillance testing for asymptomatic or presymptomatic infections, it is critical to maximising efforts to reduce transmission risk in the community,” noted the researchers.

Source: Medical-News.Net

Journal information: Rasmussen, A., and Popescu, S. (2021). SARS-CoV-2 transmission without symptoms. Science. https://science.sciencemag.org/content/371/6535/1206

Categories : COVIDTags :

A Tougher Spike Protein is Behind Transmissibility of Variants

On By ModernMedia

Researchers at Boston Children’s Hospital have analysed the structure of the SARS-CoV-2 variants, and have found that a tougher spike protein is likely responsible for their greater transmissibility.

Using a cryo electron microscope, the researchers imaged the spike protein down to the atomic level and discovered that the D614G mutation (a substitution of in a single amino acid ‘letter’ in the spike protein’s genetic code) produced a sturdier spike protein.

In the original, wild-type SARS-CoV-2, the spike protein would latch onto a cell’s ACE2 receptor and then fold in on itself, allowing the virus’ outer membrane to more easily fuse with the cell’s surface. However, they were susceptible to folding early, rendering those spike proteins useless. Around half of a SARS-CoV-2’s spike proteins would be folded in this way. However, this also made the virus harder for the immune system to lock on to.

“Because the original spike protein would dissociate, it was not good enough to induce a strong neutralising antibody response,” said research leader Bing Chen, PhD  at Boston Children’s Hospital.

When Chen and colleagues imaged the mutated spike protein, fewer are folded early because the D614G mutation blocks the shape change. While the spike protein is sturdier, it comes at the cost of being able to attach less easily to the ACE2 receptor.

“Say the original virus has 100 spikes,” Dr Chen explained. “Because of the shape instability, you may have just 50 percent of them functional. In the G614 variants, you may have 90 percent that are functional, so even though they don’t bind as well, the chances are greater that you will have infection.”

Dr Chen proposed that vaccines currently being updated should be modified for this new spike protein mutation, which should also have the side benefit of making the vaccines more effective. 

Applying structural biology to the spike protein, the team had come up with a ‘decoy’ molecule that bound to the spike protein 200 times more strongly than to the body’s ACE2 receptors. This was shown to inhibit the virus in the culture, opening up the door to a new type of treatment. 

Source: Medical Xpress

Journal information: Jun Zhang et al. Structural impact on SARS-CoV-2 spike protein by D614G substitution, Science (2021). DOI: 10.1126/science.abf2303

Categories : COVID General InterestTags :

Have COVID Restrictions Eroded The Right to Dissent?

On By ModernMedia
Image by Niek Verlaan from Pixabay

An article in The Guardian explores how the COVID pandemic and its restrictions have also may have caused an erosion in the institutions of democracy around the world.

On Saturday, a vigil at Clapham Common in the UK for Sarah Everard, a woman believed to have been murdered by a police officer, was broken up by police in a heavy-handed manner which drew widespread criticism.
Defending the Metropolitan police’s handling of the situation, assistant commissioner Helen Ball argued the force had to act “because of the overriding need to protect people’s safety” from COVID. In 2020, Black Lives Matter protestors were criticised for their actions in the first waves of the pandemic, but their actions did not cause a spike in infections. Indeed, the protests may have helped deter the spread of COVID due to their deterring people from going to restaurants and other forms of social gatherings.

While the Clapham Common event was not on the same scale, it is possible that even very large and boisterous protests are not ‘super-spreader’ events. And, according to the human rights organisation Liberty, they can be performed safely. For example a socially distanced rally was held in Tel Aviv in April last year against the Israeli prime minister, Benjamin Netanyahu, where thousands of people,   each in their own space, separated by two metres, were able to shout and wave banners.

“Protest is the lifeblood of a healthy democracy, and it’s critical that we can all stand up to those in power, and make our voices heard,” said Lana Adamou, a lawyer at Liberty. “Safe, socially distanced demonstrations are perfectly possible, and it is the duty of the police to facilitate them, not block them. The current restrictions should be interpreted compatibly with our rights enshrined in the Human Rights Act.”

However a report published by Carnegie Europe in January observed that human rights are being eroded in the name of public health, with many governments using the pandemic as a pretext to crack down on dissent.

“While governments have claimed that they were imposing measures to tackle the pandemic, these measures often have been contradictory and have excessively restricted the right to peaceful assembly,” the report said, saying that while economic activities were enabled, large protests were still prohibited. In Sweden large groups were allowed to congregate in restaurants and at sporting events, but public gatherings and protests involving more than eight people were banned. It also noted that police used tactics such as kettling, a controversial tactic where police corral protestors into tight groups before arresting them, which can increase the spread of infection.

These restrictions have forced some campaigners to become creative in their protests. In the Netherlands, climate activists filled a square in front of the Dutch parliament in the Hague with 1000 shoes from all over the country. In Croatia, a civil society movement staged balcony protests against the governance of the mayor of Zagreb.

What campaigners in some countries will be asking is whether or not the pandemic has eroded the right to dissent, and to what extent will mass public protests be allowed to return once the COVID threat has passed.

Source: The Guardian

Categories : COVIDTags :

‘3 Feet’ Social Distancing Rule Being Considered by US

On By ModernMedia

Data that suggest a ‘three feet’ social distancing rule is under consideration, according to Dr Anthony Fauci, the foremost infectious disease expert in the US.

To control COVID transmission, the World Health Organization recommends social distancing at one metre (3.3 feet), and a three feet distance used in some schools in the US is based on this. When asked about the new report on a CNN programme on Sunday, Dr Fauci agreed the data appeared to indicate that three feet is sufficient.   

While the Centers for Disease Control and Prevention do not currently recommend a rule change, Dr Fauci said that the report is being reviewed by them.

“What the CDC wants to do is accumulate data, and when data shows ability to be three feet, they will act accordingly,” Dr Fauci said, adding that its director, Dr Rochelle Walensky, was aware of the new research, with the CDC also conducting its own studies. “I don’t want to get ahead of official guidelines,” he added.

The researchers, who controlled for community rates of coronavirus in their analysis, concluded that lower physical distancing policies can safely be adopted in school settings, as long as other measures like universal masking are in place.

The study compared COVID infection rates among staff and students across 242 school districts in the state of Massachusetts, and found that schools with a three feet social distancing rule did not have a significantly different rate of transmission compared to those with the standard six feet rule.

However, there is a limitation to COVID monitoring in school-aged populations. While children may be infected as readily from COVID, they are less likely to develop illness from COVID, and so they are also less likely to get tested.

Source: NY Times

Categories : COVIDTags :

Restaurants and Not Wearing Masks Increases COVID Transmission, CDC Warns

On By ModernMedia

Fully opening restaurants and not having mask rules in place and the Centers for Disease Control (CDC) warned.

“This report is a critical reminder that with the current levels of COVID-19 in communities and the continued spread of more transmissible virus variants, which have now been detected in 48 states, strictly following prevention measures remains essential for putting an end to this pandemic,” said CDC director Rochelle Walensky, MD, at a White House COVID briefing on Friday. “It also serves as a warning about prematurely lifting these prevention measures.”

Dr Walensky’s comments may have been made with states such as Texas and Mississippi in mind, with their governors announcing that they were dropping mask mandates and allowing full reopening, including businesses such as restaurants at full capacity. Some restaurants that are still enforcing 

Research has already shown that in-person dining and lack of mask regulations contribute to the spread of COVID cases. Taking data from state and local health department websites, COVID cases and deaths were analysed at county level The team compared data from post-implementation time points, ranging from 1-20 days to 81-100 days, to pre-implementation periods.

The researchers also attempted to control for other factors, such as restaurant closures during the mask mandates, mask mandates in the restaurant reopening models, stay-at-home orders, and bans on gatherings of more than 10 people.

Of the three-quarters of surveyed counties with mask mandates, the researchers found that within 1-20 days of mask mandates, there was a 0.5 percentage point drop in COVID case growth rates. Case and death growth rates saw almost a 2.0 percentage point decline 81-100 days after mask mandates came into effect.

Conversely, states allowed restaurants to re-open for in-person dining. While the impact was not immediate, COVID case growth rates increased 1.1 percentage points 81-100 days later. However, counties allowing in-person dining were associated with 2.2 percentage point increases at days 61-80 and a 3.0 percentage point increase at days 81-100 after restrictions were lifted.

The researchers speculated about the cause, such as restaurants potentially delaying reopening even after they were allowed to do so, and that patrons might have been more cautious during initial reopenings but more likely to dine at restaurants as time passed.

Source: MedPage Today

Categories : COVIDTags :

As COVID Variants Dominate, Better Mask Use is Needed

On By ModernMedia

Evidence is accumulating that COVID is commonly transmitted through small aerosolised droplets emitted during regular speaking and breathing—a problem compounded by the enhanced contagiousness of variants such as 501Y.V2, the strain which dominates in South Africa.

Masks have become ubiquitous in the pandemic-struck world, and even fashionable, with many different types available. However, their effectiveness varies considerably from top-of-the-range N95 masks to a pulled-up shirt which offers very little protection.
“How well a mask works depends on two things: filtration and fit,” said Professor Linsey Marr, who studies airborne disease transmission at Virginia Tech .

“Good filtration removes as many particles as possible, and a good fit means that there are no leaks around the sides of your mask, where air—and viruses—can leak through,” she said, noting that even a small gap could result in a 50% reduction in effectiveness.

We do not recommend wearing more than two masks. Adding more layers proves diminishing returns and can compromise breathability. It must remain easy to breathe through the layers; otherwise, air is more likely to leak in around the sides of the mask.

Wearing a cloth mask over a surgical mask, or ‘double masking’ does improve effectiveness as it serves to tighten the surgical mask’s fit. Air escapes around the corners and edges of the mask, as anyone who has worn glasses and had them fog up in the cold can attest to.

While N95 masks are the best available, there are also equivalents such as KN95 or FFP2.

“They all provide a similar level of filtration, meaning protection of particles going in and out,” said Ranu Dhillon, a global health physician at Brigham and Women’s Hospital and Harvard Medical School. Dhillon is frustrated at the lack of transparency and education for the public about masks.

Health care workers, for example, get their masks tested for fit, something which could be also done by members of the public.

Donald Milton, a professor of environmental health at the University of Maryland, said that the key to understanding the COVID airborne transmission threat is to treat it like cigarette smoke. Ventilation helps, but if you have someone between you and an exhaust vent, then masks will definitely help.

Before the pandemic, Milton and Dhillon courted controversy by demonstrating that most viral transmission was in the form of small droplets emitted when speaking or breathing, and the contribution to transmission by coughing and sneezing was smaller than previously thought. The two researchers are hopeful that their findings will find their way into official COVID policy, and future research may even see masks becoming a common sight during peak flu seasons.

Source: Japan Times

Categories : COVIDTags :

Viral Load Drives the Transmission of COVID

On By ModernMedia

Knowing what factors drive the transmission of COVID is crucial to informing schemes to contain and adapt to its spread.

There is abundant data on location and duration of exposure to COVID, but there is precious little on any other factors, the researchers noted.

The SARS-CoV-2 virus is detectable in respiratory tract samples 1-2 days before symptom onset, and can continue for several weeks afterward. But the detection of viral RNA is not necessarily related to infectiousness, and no studies had established the connection between viral load and COVID transmission, although viral load had been linked to COVID mortality.

The researchers used linked index cases of COVID to determine that viral load was the principle factor behind COVID transmission, and is the largest such study to date. This emphasises the need for initiating proper contact tracing.

The researchers conducted a post-hoc analysis of 314 cases during the initial COVID wave in Spain, of whom 90% (282) had at least one close contact, resulting in a total of 753 contacts. Viral load was the key indicator of COVID transmission.

The overall secondary attack rate (proportion of COVID-positive contacts) during the study period was 17%. However, this rate varied from 12% when the viral load of the index case was lower than 1×10⁶ copies per mL, to 24% when it was 1×10¹⁰ copies per mL or higher.

Running multivariate analyses, the researchers found no association between sex, age, diabetes, cardiovascular disease, or respiratory disease and the risk of or time to developing symptomatic COVID. There was a significant association of incubation time with initial viral load, increasing from five days among patients with a high viral load to seven days among participants with a low viral load.

The researchers wrote: “Taken together, our results indicate that the viral load, rather than symptoms, might be the predominant driver of transmission.”

They conclude that all cases should be considered potential transmitters of the virus. They also suggest viral load assessment in patients with large numbers of contacts, and risk stratification by time to symptom appearance based on viral load. 

Source: News-Medical.Net

Journal information: Marks M, et al. Transmission of COVID-19 in 282 clusters in Catalonia, Spain: a cohort study. The Lancet Infectious Disease, 2021. DOI: https://doi.org/10.1016/S1473-3099(20)30985-3, https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30985-3/fulltext

Categories : COVID Expert OpinionTags :

UCT Expert Talks COVID and Warns of Third Wave

On By ModernMedia

If South Africa does not pursue a rapid vaccination programme to achieve herd immunity, it may face a third wave as a consequence, warned a leading local expert.

Professor Marc Mendelson of UCT’s Division of Infectious Diseases and HIV Medicine at Groote Schuur Hospital made these statements while speaking during a virtual Summer School lecture on Saturday, titled “COVID-19 Insights and Lessons”.

“Without rapid vaccination of at least two thirds of the population, we [South Africa] are not going to get to population immunity, and without that, we will see another wave,” Mendelson warned.

However, he emphasised that much had been accomplished in the battle against COVID. “It is associated with a scientific endeavour that we have never seen before. We’re definitely better off a year down the line, but there are a huge number of things that we need to answer. As a country we still face deep problems with severe issues around vaccine strategy, and we haven’t even talked about vaccine denial,” he said.

Criticism has been directed at the South African government because of its failure to start a vaccination programme, despite its huge case load and status as Africa’s most wealthy nation. A leaked phone call from a Pfizer executive has only added to this, as it was revealed that for months SA health officials had not been responding to requests for vaccine discussions.

Regarding COVID transmission, he said that the virus resided in the upper respiratory tract as well as the lungs, and that it could be expelled in aerosol droplets. The clinical and epidemiological evidence suggested that larger, heavier droplets carried the virus.

“The household infection rates were high. A very large number of cases, the vast majority [in fact], were within families in close proximity [to one another]. This, epidemiologically, suggests that large droplets play a role in transmission.

“If you want to reduce transmission from large droplets, then you need to increase the distance you are from someone. Also, because droplets drop onto surfaces … you will need to clean surfaces and wash your hands well. This is the science behind the use of masks, handwashing, social distancing and ventilation.”

However, he added that a number of studies had found the virus in remote corners of hospitals at a distance from patients, suggesting that it had been carried there by smaller, aerosolised particles.

“If you want to reduce aerosols, one way of doing that is to improve ventilation. The more the air is changed, the [quicker] it will dilute small droplets,” he said.

Source: University of Cape Town