The role of built environments in preventing contamination and reducing the spread of Covid-19 for future pandemics

‘The built environment contributes to the spread and contamination of the virus, as people spend more than 90% of their time indoors and even more during lockdown and community quarantine. During the current pandemic, healthy and asymptotic individuals are staying in their houses, and many people that are affected by the virus are now in hospitals and in healthcare facilities. These situations might affect the spread and contamination of the virus, as well as individuals’ interactions with each other.

‘To reduce the contamination and spread of the virus in the built environment that might affect healthy individuals – such as health care professionals, office workers – it is important to understand the steps that need to be taken and the policies to be implemented along with the theories underlying them. One of the approaches to be considered in designing effective fresh air supply and air extraction ventilation systems to minimize the concentration of suspended viruses. This is in addition to other essential procedures to understand the movement of viruses in the indoor air and its suspension/resuspension to and from surfaces.’

• Is it safe to reopen theaters during the Covid-19 pandemic?
• What’s in the pipeline? Evidence on the transmission of SARS-CoV-2 via building wastewater plumbing systems
• Ventilation for residential buildings: Critical assessment of standard requirements in the Covid-19 pandemic context
• Ventilation system design and the coronavirus (Covid-19)
• Outdoor airborne transmission of coronavirus among apartments in high-density cities

Read here (Frontiers in Built Environment, as at September 12, 2021)

How the Delta variant achieves its ultrafast spread

‘Viral load is roughly 1,000 times higher in people infected with the Delta variant than those infected with the original coronavirus strain, according to a study in China...

‘The combination of a high number of viruses and a short incubation period makes sense as an explanation for Delta’s heightened transmissibility, says epidemiologist Benjamin Cowling at the University of Hong Kong. The sheer amount of virus in the respiratory tract means that superspreading events are likely to infect even more people, and that people might begin spreading the virus earlier after they become infected.

‘And the short incubation makes contact tracing more difficult in countries such as China, which systematically tracks each infected person’s contacts and require them to quarantine. “Putting it all together, Delta’s really difficult to stop,” Cowling says.’

Read here (Nature, July 21, 2021)

Indian Covid mutant more contagious, but not vaccine resistant: Top WHO scientist

“Surge in India increases chances of more dangerous variants emerging. Prelim data shows that Indian variant is more contagious. There is heterogeneity in India in terms of spread of Covid-19. WHO is concerned about number of cases and deaths in India. Globally, cases and deaths have plateaued, not in South Asia. South East Asia is seeing case rise owing to India. Overall numbers hide what is going on, need to go deeper in state, local level data,” she said.

‘Speaking on efficacy of vaccines available in India, she assured, “There is no enough data to show that double mutant is vaccine resistant. All the available vaccines today in India and elsewhere prevent severe disease and death even if you get up the infection. You are not going to end up in the ICU critically ill. The message is take the vaccine whichever is available and you eligible for it. If your turn is there, please take it.”

Read here (Yahoo, May 10, 2021)

Antiseptic throat spray can reduce Covid-19 spread in high-risk settings, say Singapore researchers

‘A type of antiseptic throat spray, as well as an oral drug usually prescribed to treat malaria and arthritis, have been found to be effective in reducing the spread of COVID-19 in high-transmission settings, said Singapore researchers on Sunday (Apr 25).

‘The findings were made after a large-scale clinical trial conducted last May, involving more than 3,000 migrant workers living in Tuas South dormitory.

‘During the six-week trial, workers were given a povidone-iodine throat spray, which can be bought off the counter, and oral hydroxychloroquine, which requires a prescription.’

Read here (Channel News Asia, Apr 25, 2021)

Sweden has highest new Covid cases per person in Europe

‘Sweden has reported Europe’s highest number of new coronavirus infections per head over the past week and has more patients in intensive care than at any time since the pandemic’s first wave.

‘The Scandinavian country, which has opted against strict lockdowns but gradually ratcheted up its still mostly voluntary restrictions, has a seven-day average of 625 new infections per million people, according to ourworldindata.org.

‘That compares with 521 in Poland, 491 in France, 430 in the Netherlands, 237 in Italy and 208 in Germany, the data showed. The figure was many times higher than the 65, 111 and 132 per million in Sweden’s Nordic neighbours Finland, Denmark and Norway.’

Read here (The Guardian, Apr 13, 2021)

CDC: Covid-19 surface transmission risk below 1 in 10,000

‘The likelihood of contracting Covid-19 from touching contaminated surfaces is low at less than one in 10,000, announced the United States’ Centers for Disease Control and Prevention (CDC).

‘In new guidance released on April 5, the CDC said although it is possible for people to contract the coronavirus from surface transmission, the main mode of transmission of the disease is through direct contact with an infected person, droplet transmission (most likely to occur when one is within two metres of an infected person exhaling virus-containing respiratory droplets), and airborne transmission (exposure to smaller virus-containing respiratory droplets that can remain suspended in the air).’

Read here (Code Blue, Apr 9, 2021)

Coronavirus fact-check #10: Why “new cases” are plummeting... ‘It's not vaccines, it's not lockdown’

‘Essentially, in two memos the WHO ensured future testing would be less likely to produce false positives and made it much harder to be labelled an “asymptomatic case”.

‘In short, logic would suggest we’re not in fact seeing a “decline in Covid cases” or a “decrease in Covid deaths” at all.

‘What we’re seeing is a decline in perfectly healthy people being labelled “covid cases” based on a false positive from an unreliable testing process. And we’re seeing fewer people dying of pneumonia, cancer or other disease have “Covid19” added to their death certificate based on testing criteria designed to inflate the pandemic.’

Read here (Off Guardian, Feb 26, 2021)

A quite possibly wonderful summer

‘The summer of 2021 is shaping up to be historic... After months of soaring deaths and infections, COVID-19 cases across the United States are declining even more sharply than experts anticipated. This is expected to continue, and rates of serious illness and death will plummet even faster than cases, as high-risk populations are vaccinated. Even academics who have spent the pandemic delivering ominous warnings have shifted their tone to cautiously optimistic now that vaccination rates are exploding.’

Read here (The Atlantic, Feb 19, 2021)

Covid-19 cases are dropping fast. Why?

‘One month ago, the CDC published the results of more than 20 pandemic forecasting models. Most projected that COVID-19 cases would continue to grow through February, or at least plateau. Instead, COVID-19 is in retreat in America. New daily cases have plunged, and hospitalizations are down almost 50 percent in the past month. This is not an artifact of infrequent testing, since the share of regional daily tests that are coming back positive has declined even more than the number of cases. Some pandemic statistics are foggy, but the current decline of COVID-19 is crystal clear.

**Four reasons: social distancing, seasonality, seroprevalence, and shots.’

Read here (The Atlantic, Feb 17, 2021) 

Protein behind corona’s slow Asia spread: Study

‘Deficiency in a particular human protein, which is more common in Europe and the United States than in Asia, could explain why coronavirus is not spreading as fast in Asian countries. A team of scientists from the National Institute of Biomedical Genomics in Kalyani, West Bengal, have found a biological reason for the slower spread of a mutant of coronavirus in Asia compared to the West. The team has explained how higher levels of a human protein — neutrophil elastase — helps the virus to enter the human cell, multiply and also spread faster from infected individuals... 

“However, some naturally-occurring mutations in the AAT-producing gene results in deficiency of the AAT protein. This deficiency is known to be much higher in the Caucasians of Europe and America than among Asians,” said Majumder. “While we used AAT deficiency data from East Asia, along with North America and Europe, for the study, considering the pace at which the coronavirus is spreading, the numbers are representative of other Asian regions too, including India.”... 

‘As per their data, AAT deficiency is the least in East Asian countries — 8 per 1,000 individuals in Malaysia, 5.4 per 1,000 in South Korea, 2.5 in Singapore. On the other hand, 67.3 in per 1,000 individuals in Spain are AAT deficient, 34.6 in the UK and 51.9 in France and in the US it is prevalent in 29 individuals among 1,000.’

Read here (Times of India, Feb 9, 2021)

Viral loads, including in asymptomatic cases, a key factor in transmission

‘The scientific community is still uncovering the full picture of SARS-CoV-2 transmission dynamics. A study published in The Lancet: Infectious Diseases analyzed SARS-CoV-2 transmission among clusters in Catalonia, Spain, to understand the relationship between viral load and transmission risk. The researchers utilized participant data from a previous clinical trial, and they identified 314 COVID-19 patients that met their inclusion criteria. Among those patients, 282 had at least 1 contact (753 total contacts). The index patients infected 125 secondary cases, corresponding to a secondary attack rate of 17%. 

‘The researchers identified a statistically significant association between viral load in the index patients and the subsequent secondary attack rate. Among index patients with the lowest viral load, index patients exhibited a secondary attack rate of 12%, compared to 24% among the highest group. The researchers estimate that the odds of secondary transmission increase 30% for every log(10) increase in viral load. Additionally, the study found increased likelihood that secondary cases would develop COVID-19 symptoms associated with increased viral load in the index patients (aHR of 1.12 per log(10) increase in viral load). While further research is needed to more fully characterize the factors associated with transmission, this study provides evidence that the index patient’s viral load could be a major driver of secondary transmission risk and potentially disease severity in secondary cases.’ (Source: Updates on the COVID-19 pandemic from the Johns Hopkins Center for Health Security.)

Transmission of COVID-19 in 282 clusters in Catalonia, Spain: a cohort study

Read original here (The Lancet, Feb 2, 2021)

Covid-19 rarely spreads through surfaces. So why are we still deep cleaning?

‘Armed with a year’s worth of data about coronavirus cases, researchers say one fact is clear. It’s people, not surfaces, that should be the main cause for concern. Evidence from superspreading events, where numerous people are infected at once, usually in a crowded indoor space, clearly point to airborne transmission, says Marr. “You have to make up some really convoluted scenarios in order to explain superspreading events with contaminated surfaces,” she says.

‘Hand washing is crucial, says Marr, because surface transmission can’t be ruled out. But it’s more important to improve ventilation systems or to install air purifiers than to sterilize surfaces, she says. “If we’ve already paid attention to the air and we have some extra time and resources, then yes, wiping down those high-touch surfaces could be helpful,” she says.

‘Households can also ease up, says Pickering. Quarantining groceries or disinfecting every surface is going too far. “That’s a lot of work and it also is probably not reducing your exposure that much,” she says. Instead, reasonable hand hygiene, as well as wearing a mask and social distancing to reduce exposure from close contacts is a better place to focus efforts.’

Read here (Nature, Jan 29, 2021)

Vaccines need not completely stop Covid transmission to curb the pandemic

‘Influenza may provide the best blueprint of what to expect going forward. The most common flu vaccine—the inactivated virus—is not “truly sterilizing because it doesn’t generate local immune response in the respiratory tract,” Crowcroft says. This fact, coupled with low immunization rates (often shy of 50 percent among adults) and the influenza virus’s ability to infect and move between multiple species, enables it to constantly change in ways that make it hard for our immune system to recognize. Still, depending on the year, flu vaccines have been shown to reduce hospitalizations among older adults by an estimated 40 percent and intensive care admissions of all adults by as much as 82 percent.

‘Research on seasonal coronaviruses suggests that SARS-CoV-2 could similarly evolve to evade our immune systems and vaccination efforts, though probably at a slower pace. And data remain mixed on the relationship between symptoms, viral load and infectiousness. But ample precedent points to vaccines driving successful containment of infectious diseases even when they do not provide perfectly sterilizing immunity. “Measles, diphtheria, pertussis, polio, hepatitis B—these are all epidemic-prone diseases,” Crowcroft says. “They show that we don’t need 100 percent effectiveness at reducing transmission, or 100 percent coverage or 100 percent effectiveness against disease to triumph over infectious diseases.”

Read here (Scientific American, Jan 18, 2021)

Pfizer/BioNTech vaccine appears effective against mutation in new coronavirus variants: Study

‘Pfizer Inc and BioNTech’s COVID-19 vaccine appeared to work against a key mutation in the highly transmissible new variants of the coronavirus discovered in the UK and South Africa, according to a laboratory study conducted by the U.S. drugmaker.

‘The not-yet peer reviewed study by Pfizer and scientists from the University of Texas Medical Branch indicated the vaccine was effective in neutralizing virus with the so-called N501Y mutation of the spike protein.’

Read here (Reuters, Jan 7, 2021)

More or less deadly? Which way is SARS-CoV-2 evolving?

‘Like plague, Covid-19 is a stealth infection, and that might ultimately slow evolution toward lower virulence. Yersinia pestis, the germ that causes plague, tamps down the early immune response, so that infected people can travel and spread infection for days before they feel sick. Similarly, people infected with SARS-CoV-2 seem capable of infecting others before experiencing any symptoms. This sly mode of viral spread may make the evolution of lower virulence less likely, as infected but asymptomatic people are the perfect mobile viral delivery systems.

‘Yet even without an evolutionary process pushing SARS-CoV-2 towards lower virulence, over time, the virus might affect people differently, said Columbia University virologist Vincent Racaniello. “SARS-CoV-2 may become less deadly, not because the virus changes, but because very few people will have no immunity,” he said. In other words, if you’re exposed to the virus as a child (when it doesn’t seem to make people particularly sick) and then again and again in adulthood, you’ll only get a mild infection. Racaniello points out that the four circulating common cold coronaviruses “all came into humans from animal hosts, and they may have been initially quite virulent.” Now, he says, they infect 90 percent of children at young ages. At later ages, all you get is the common cold.’

Read here (Genetic Literacy Project, Jan 7, 2021)

The mutated virus is a ticking time bomb

‘There is much we don’t know about the new COVID-19 variant—but everything we know so far suggests a huge danger.

‘A more transmissible variant of COVID-19 is a potential catastrophe in and of itself. If anything, given the stage in the pandemic we are at, a more transmissible variant is in some ways much more dangerous than a more severe variant. That’s because higher transmissibility subjects us to a more contagious virus spreading with exponential growth, whereas the risk from increased severity would have increased in a linear manner, affecting only those infected.’

Read here (The Atlantic, Jan 1, 2021) 

A pandemic atlas: How Covid-19 took over the world in 2020

‘Journalists from The Associated Press around the world assessed how the countries where they are posted have weathered the pandemic — and where those countries stand on the cusp of year two of the contagion.’ Wonderful pictures...

View here (Associated Press, Dec 16, 2020)

Coronavirus: How can we imagine the scale of Covid's death toll?

‘The suffering from the coronavirus pandemic has come to define 2020. But how do you grasp the immense scale of loss? Flowers - symbols of grief, peace, and love - serve as a tribute to those who have died.

‘Imagine the pandemic as a  flower. In the animation below, the stem grows as Covid-19 cases increase over time and the petals unfurl as more people die with the disease.’

View here (BBC, Dec 7, 2020)

UK ready for roll-out but Pfizer CEO 'not certain' if vaccine stops transmission

‘Days after getting back-to-back approvals from the United Kingdom (UK) and Bahrain health regulatory bodies for the emergency use of its coronavirus vaccine, Pfizer Inc CEO Albert Bourla is now "not certain" if the company-made vaccine to prevent the Covid-19 can actually stop the transmission of the infection. The basic.

‘...during an interview with NBC's Lestor Holt, Pfizer CEO, when asked whether a person can still transmit the virus after vaccination, said he was "not certain". "I think this is something that needs to be examined. We are not certain about that right now with what we know," he was quoted as saying.’

Read here (India Today, Dec 6, 2020)

Moderna's chief medical officer says that vaccine trial results only show that they prevent people from getting sick — not necessarily that recipients won't still be able to transmit the virus

‘Moderna Chief Medical Officer Tal Zaks told Axios that the public should not "over-interpret" the vaccine trial results to assume life could go back to normal after adults are vaccinated. "They do not show that they prevent you from potentially carrying this virus transiently and infecting others," Zaks told Axios.  While he believes, based on the science, that it's likely that vaccine does prevent transmission, but said there's still no solid proof of that yet. "I think it's important that we don't change behavior solely on the basis of vaccination," he said.’

Read here (Business Insider, Nov 24, 2020)