COVID Booster: Inhalable droplets and talking to kids

Nebuliser might be responsible for transmission in hotel quarantine

Nebulisers – medical devices that turn liquid medicines into tiny, inhalable droplets – made the news this week as authorities investigated the reason for Melbourne’s hotel quarantine outbreak and subsequent five-day lockdown.

Monash University’s Daniel Duke, a researcher in inhaled drug delivery devices and aerosols, thinks that it’s likely a nebuliser is the culprit.

“A lot of the aerosol from the nebuliser will naturally escape into the room; far more than would naturally be emitted by normal breathing,” he says. “A substantial portion of that aerosol has been in contact with the person’s upper airway. If they happen to be shedding a lot of virus at the time of use, there might be an increased risk of aerosol spread.”

But Duke’s theory is untested. “I must emphasise that right now we don’t have clear scientific evidence that nebulisers can increase the spread of COVID-19 specifically. This is a question for epidemiologists to look into,” he says.

Nebulisers are frequently used for medical care, including to treat COVID-19. For example, a pre-print study released this week suggests budesonide, an asthma medication taken via inhaler, might reduce chances of hospitalisation for those diagnosed with COVID-19.

WHO finds animal host the likely source for COVID-19

After a month-long investigation, the World Health Organization has announced that SARS-CoV-2 most likely came from an animal host and was possibly spread through frozen food.

“There are no surprises here in the report,” says Hassan Vally, an associate professor in epidemiology at La Trobe University. “The most likely explanation for the pandemic was always that it emerged in a similar way to which SARS did back in the early 2000s – that is, it involved the jumping of the virus from an animal host to humans.

“There really wasn’t any plausible reason for us to think anything else had occurred given what we know about new pathogens and their origins.

“If this puts some of the conspiracy theories to rest while we focus on the job at hand in controlling the pandemic, then this has probably made the international mission worth it. Clearly there is more work that needs to be done to understand as much as we can about the origin of this virus that has caused so much upheaval in the world.”

Further evidence that masks reduce the spread of COVID-19

A new review has compiled more data showing that masks prevent people from spreading COVID-19, and protect them against contracting the virus.

The review, published in the Journal of the American Medical Association, collated evidence from 11 other studies that investigated mask wearing. They ranged from small-scale case studies with a few dozen participants, to state- and country-level analyses – including one that examined Canada’s whole-of-country mask usage.

Masks are a difficult medical intervention to control for compared to medications or vaccines, so data on mask wearing at the start of the pandemic was patchy. But now, with so many places implementing mask use, there’s much more information. “During the pandemic, the scientific evidence has increased,” the authors write. “Compelling data now demonstrate that community mask wearing is an effective nonpharmacologic intervention to reduce the spread of this infection.”

The review also reiterated that cloth masks with two or three layers provide more protection than those with one layer.

Computer model suggests timing very important when introducing travel restrictions

Modelling covid
Timing has a large impact on the efficacy of travel bans. Credit: Peter Zelei Images / Getty Images

Australia’s response to the pandemic has featured frequent border closures and early lockdowns, especially in response to breaches in hotel quarantine. A new study published in The Royal Society suggests that travel bans and mobility restrictions are most effective when introduced early in a pandemic. In contrast, social distancing measures like closing schools and banning large gatherings are effective at any time during an outbreak.

The study computer-simulated different restrictions, calibrating their model with data from the outbreak in Italy during February–March last year. It found that travel bans could dramatically reduce infections in the first stages of the outbreak, but they were less effective if implemented once the virus had already spread. Restrictions that reduced activities, however, flattened the curve even when the virus was already prevalent.

These interventions will still be critically important to the control of COVID-19 until vaccinations are fully rolled out. “To date, the only effective means to respond to the spreading of COVID-19 pandemic are […] policies to reduce social activity and mobility restrictions,” the authors write.

How children have learned about COVID-19

Half of Australian parents avoid talking about COVID-19 deaths with their children, according to new research.

The international study, published in PLOS One, surveyed 390 children from April to June last year, including 49 from Australia. The report also surveyed 123 Australian parents, and found that 51% of them said that while their children knew the virus was deadly, they wouldn’t talk about death with them.

The children in the study, who were aged between 7 and 12, said their parents were the primary sources of information on the pandemic. Most children thought they knew “quite a bit” about the pandemic. They most wanted to know when the pandemic would end, or if there was a cure.

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