COVID news and trends @ 30 October

The numbers

At a media briefing on 26 October, WHO director-general Tedros Adhanom Ghebreyesus told reporters: “Last week saw the highest number of COVID-19 cases reported so far. Many countries in the northern hemisphere are seeing a concerning rise in cases and hospitalisations. And intensive care units are filling up to capacity in some places, particularly in Europe and North America.

“Over the weekend, a number of leaders critically evaluated their situation and took action to limit the spread of the virus. We understand the pandemic fatigue that people are feeling. It takes a mental and physical toll on everyone. Working from home, children being schooled remotely, not being able to celebrate milestones with friends and family or not being there to mourn loved ones – it’s tough and the fatigue is real.

“Leaders must balance the disruption to lives and livelihoods with the need to protect health workers and health systems as intensive care fills up. In March, health workers were routinely applauded for the personal sacrifice they were making to save lives. Many of those health workers, who have themselves gone through immense stress and trauma, are still on the frontlines, facing a fresh wave of new patients. 

“We must do all we can to protect health workers, and the best way to do that is for all of us to take every precaution we can to reduce the risk of transmission, for ourselves and others. No one wants more so-called lockdowns. But if we want to avoid them, we all have to play our part. The fight back against this pandemic is everyone’s business.”

Global

As at 15:58 CET on Wednesday 28 October, cases confirmed worldwide by national authorities stood at 43,766,712 (404,159 of them reported in the preceding 24 hours). 1,163,459 deaths have been recorded (5780). (Source: WHO Coronavirus Disease Dashboard)

Johns Hopkins University’s Centre of Systems Science and Engineering (CSSE) reported (at 16:30 AEST on Thursday 29 October) 44,482,501 confirmed cases and 1,174,031 deaths. 

Australia

The Department of Heath reported on 28 October that national confirmed cases stood at 27,554, a rise of 14 in 24 hours. 907 deaths have been recorded.

State by state: ACT 114 total cases (first case reported 12 March); NSW 4406 (25 January); NT 33 (20 March); Qld 1169 (29 January); SA 495 (2 February); Tas 230 (2 March); Vic 20,342 (25 January); WA 765 (21 February).

Research

Lingering droplets perhaps not a real problem

Physics has been very much to the fore in the quest to better understand COVID-19 and its impact, with research looking in particular at how far and fast particles travel in the air.

A new study from The Netherlands suggests that aerosol microdroplets, the tiny particles that linger longest after we talk, cough or sneeze, are not particularly efficient at spreading the virus.

Physicists and medical doctors at the University of Amsterdam used laser technology to measure the distribution of droplets. Subjects spoke or coughed into a laser beam, and a jet nozzle was used to mimic tiny aerosol microdroplets.

While the lingering microdroplets are certainly not risk-free, due to their small size they contain less virus than the larger droplets that are produced when someone coughs, speaks, or sneezes directly on us, says Daniel Bonn, co-author of the team’s paper in Physics of Fluids.

“Based on the current insights, we actually see that aerosol-wise, it’s relatively safe to go into well-ventilated modern buildings, such as airports, train stations, modern offices,” he says.

If someone enters a space even a few minutes after a mildly symptomatic carrier of the coronavirus has coughed in that area, the probability of infection is “rather low”, according to the researchers. It is even lower if that person was only talking.

They acknowledge the findings are “necessarily subjective”, but hope they provide some context as people consider their safety during the pandemic. And, they stress, they support the efficacy of wearing masks, social distancing, and other measures targeting the spread of larger droplets.

Random effects key to containing epidemics

German researchers say mathematics and computer simulations show why dividing a large population into multiple subpopulations that don’t intermix can help contain outbreaks without imposing contact restrictions within those local communities.

It all comes down to the impact, or otherwise, of random events, they suggest in a paper in the journal Chaos.

Ramin Golestanian and Philip Bittihn from the Max Planck Institute for Dynamics and Self-Organisation first considered a so-called deterministic model without random events. They assumed that individuals in each subpopulation would encounter others at the same rate they would in the large population.

Even though subpopulations are not allowed to intermix, the same dynamics are observed in the subdivided population as in the initial large population. If, however, random effects are included in the model, they say, dramatic changes ensue, even though the contact rate in the subpopulations is the same as in the full one.

Looking at a population of eight million people with 500 initially infected, and an infectious contact rate seen for COVID-19 with mild social distancing measures in place, they found that the disease spreads exponentially, with infections doubling every 12 days.

“If this population is allowed to mix homogeneously, the dynamics will evolve according to the deterministic prediction with a peak around 5% infected individuals,” said Bittihn.

However, if the population is split into 100 subpopulations of 80,000 people each, the peak percentage of infected individuals drops to 3%. If the community is split up even further to 500 subgroups of 16,000 each, the infection peaks at only 1% of the initial population.

The main reason subdividing the population works is because the epidemic is completely extinguished in a significant fraction of the subgroups. This “extinction effect” occurs when infection chains spontaneously terminate.

“In reality, subpopulations cannot be perfectly isolated, so local extinction might only be temporary,” Golestanian says. “Further study is ongoing to take this and suitable countermeasures into account.”

Coronaviruses are masters of mimicry

Coronaviruses are adept at imitating human immune proteins that have been implicated in severe COVID-19 disease, a study from Columbia University, US, has found.

The concept itself is not unusual. Just as some plants and animals use mimicry to trick prey or predators, viral proteins can mimic the three-dimensional shapes of their host’s proteins to trick the host into helping the virus complete its life cycle.

What surprises Sagi Shapira and colleagues is the extent of it. Hypothesising that identifying viral-protein look-alikes would provide clues to the way viruses cause disease, they turned to supercomputers and a program similar to 3D facial recognition software. After scanning more than 7000 viruses and 4000 hosts across Earth’s ecosystems, they uncovered six million instances of viral mimicry.

“Mimicry is a more pervasive strategy among viruses than we ever imagined,” Shapira says. “It’s used by all kinds of viruses, regardless of the size of the viral genome, how the virus replicates, or whether the virus infects bacteria, plants, insects or people.”

The key to all this is that some types of viruses used mimicry more than others – and coronaviruses are particularly good at it.

They were found to mimic over 150 proteins, including many that control blood coagulation or activate complement – a set of immune proteins that help target pathogens for destruction and increase inflammation in the body.

The findings are reported in the journal Cell Systems.

Impact of air pollution on COVID-19 deaths

Long-term exposure to air pollution could contribute to around 15% of COVID-19 deaths worldwide, according to a new international study.

In a paper in the journal Cardiovascular Research, the authors say the impact in individual countries ranges from 29% in the Czech Republic, 27% in China and 26% in Germany to 8% in Ireland, 6% in Israel, 3% in Australia and just 1% in New Zealand.

These proportions, they write, are an estimate of “the fraction of COVID-19 deaths that could be avoided if the population were exposed to lower counterfactual air pollution levels without fossil fuel-related and other anthropogenic [caused by humans] emissions”.

To this they add that that the “attributable fraction” does not imply a direct cause-effect relationship between air pollution and COVID-19 mortality – although it is possible.

The research team, from Germany, Italy, the US and the UK, used epidemiological data from previous US and Chinese studies of air pollution and COVID-19 and the SARS outbreak in 2003, supported by additional data from Italy.

To create their model, they combined this with satellite data, information on atmospheric conditions and ground-based pollution monitoring networks. The study is the first of its kind to distinguish between fossil fuel-related and other human-made sources of air pollution.

The results are based on epidemiological data collected up the third week in June 2020 and the researchers say a comprehensive evaluation will need to follow after the pandemic has subsided.

In brief

Healthcare workers and their families make up 11% of the working age population (18-65 years) but account for 17% of hospital admissions for COVID-19, according to a study from Scotland published in medical journal The BMJ. While hospital admission in this age group was very low overall, patient-facing healthcare workers were three times more likely to be admitted than others. The study was undertaken during Scotland’s first wave of infection (1 March to 6 June). The researchers note that it was an observational study, so can’t establish cause.

Delaying social distancing measures, failing to stick to them, and ending them early all cause COVID-19 case numbers to rocket, according to a study led by the University of Wisconsin-Madison. Researchers developed a computer model for three US regions. They found New York City could have slashed infections by 80% had it implemented social distancing a week earlier than it did, while delaying a further week would likely have seen five times as many cases as occurred. The data also showed that face mask use after distancing measures are eased has a big effect in cutting transmission of the virus. The findings are published in Annals of Internal Medicine.

Some patients with COVID-19 have persistent skin-related symptoms long after their initial infection has cleared, researchers from Massachusetts General Hospital, US, told this week’s 29th Congress of the European Academy of Dermatology and Venereology. They established an international registry for COVID-19 skin manifestations in April, subsequently evaluating around 1000 cases of “long haulers” – defined as anyone with symptoms that persisted for at least 60 days. “The skin is potentially a visible window into inflammation that could be going on in the body,” notes senior author Esther E. Freeman.