COVID Booster: Pandemic probabilities, spring in China, and breathing apparatus

Large pandemics might be more likely than we thought, according to statisticians

An analysis of disease outbreaks over the past 400 years has found that the probability of a COVID-like pandemic breaking out in any given year is around 2%. This means that someone born in the year 2000 would have a roughly 38% chance of experiencing a pandemic by now.

“The most important takeaway is that large pandemics like COVID-19 and the Spanish flu are relatively likely,” says Dr William Pan, associate professor of global environmental health at Duke University in the US, and co-author of a paper on the research, published in PNAS.

“This points to the importance of early response to disease outbreaks and building capacity for pandemic surveillance at the local and global scales, as well as for setting a research agenda for understanding why large outbreaks are becoming more common.”

How much did travel bans help?

Modelling by the CSIRO has found that the international travel bans brought in by the Australian government in early 2020 reduced the number of imported COVID cases by 88%.

The researchers used the progressive travel bans in early 2020 – first against China, then Iran, South Korea and Italy, before the rest of the world – to develop a modelling tool.

“Our modelling shows that without travel restrictions, over 48,000 COVID-19 cases were likely to have been imported to Australia from January to May 2020,” says Dr Jess Liebig, a research scientist at CSIRO. 

“However, all of Australia’s travel bans successfully lowered imported cases into Australia by 88%, to an estimated 6,000 cases over the studied period.”

The modelling tool, described in BMC Public Health, can also forecast the number of potential infections on each incoming international flight, helping to guide border-reopening decisions.

“It also enables us to pinpoint the groups of travellers most likely to be carrying the virus, so authorities can more efficiently direct healthcare and biosecurity control strategies,” says Liebig.

One in three Americans caught COVID in 2020

While travel bans appear to have worked in Australia, a very different story played out across the Pacific. A study in Nature has found that 103 million US residents, or 31% of the country’s population, had been infected with SARS-CoV-2 by the end of 2020.

The researchers, based at Columbia University, used modelling to examine the spread of the coronavirus. The model suggested that fewer than a quarter (22%) of infections were accounted for in official numbers.

“The vast majority of infections were not accounted for by the number of confirmed cases,” says Jeffrey Shaman, professor of environmental health sciences at Columbia and co-author on the paper.

“It is these undocumented cases, which are often mild or asymptomatic infectious, that allow the virus to spread quickly through the broader population.”

The virus was not distributed evenly, and peaked at different times in different cities. In some areas – like the Dakotas, Minnesota, Wisconsin and Iowa – over 60% of the population was estimated to have caught COVID by the end of 2020.

Cheap breathing device for COVID patients

A new type of continuous positive airway pressure (CPAP) machine, which costs around £150 ($284 AUD) to make, begins trials for treating COVID in a Ugandan hospital this month.

“In the UK, CPAP has been effective as the mainstay of respiratory treatment for severe COVID-19 and helps to keep patients from needing advanced ICU care such as ventilators,” says Dr Tom Lawton, a consultant at Bradford Teaching Hospitals in the UK and a researcher on the project. (For comparison, ventilators cost tens of thousands of dollars.)

“In many countries, resource limitations mean that even CPAP is difficult to come by, and more severe disease frequently leads to death. Simple CPAP devices, designed to operate in a resource-limited setting, can help reduce global healthcare inequality and save lives both now with COVID-19 and potentially with other diseases in the future.”

The device operates with a simple fan. “The fan or CPAP blower is connected to what is known as a breathing circuit,” explains Dr Pete Culmer, associate professor of mechanical engineering at Leeds University in the UK.

“That circuit is made up of a filter to catch viruses and bacteria in the air flow, tubing, face mask, a valve which controls the flow of oxygen from the oxygen concentrator, and an expiration outlet.”

Researchers at the Mengo Hospital in Uganda – who also collaborated on the project – will be trialling the device next month.

A paper describing the device is published in Frontiers in Medical Technology.

Lockdown brought spring on earlier in China

The spring of 2020 arrived earlier in China because of reduced human activity, according to research published in Science Advances.

The researchers, who are based in China, Australia, South Africa and the US, used satellite data to examine the greenness of vegetation around China in early 2020.

Following the introduction of restrictions in January, travel around the country decreased and there were fewer particulates in the air. The researchers found that this led to more warming from the Sun, hastening the greening of vegetation.

“The onset of spring in 2020 occurred 8.4 days earlier,” the researchers write in their paper. The vegetation was also greener than average.

“This study reveals that on temporal scales of weeks to months, reduction in human activities can have rapid positive effects on the environment across large spatial scales,” they add.