Did climate change help SARS-CoV-2?
A new study published in the journal Science of the Total Environment has provided the first evidence of how climate change could have played a direct role in the emergence of the SARS-CoV-2 virus: global greenhouse gas emissions over the last century have made southern China a hotspot for bat-borne coronaviruses, by driving growth of bats’ preferred forest habitat.
“Understanding how the global distribution of bat species has shifted as a result of climate change may be an important step in reconstructing the origin of the COVID-19 outbreak,” says the University of Cambridge’s Robert Beyer, first author of the study.
Using temperature, precipitation and cloud-cover records, the researchers created a map of the world’s vegetation as it was a century ago. Then they used information on the vegetation requirements of the world’s bat species to work out the global distribution of each species at the time. Last, they compared this to current distributions to see how the number of different bat species has changed across the globe over the last century.
The world’s bat population carries about 3,000 different types of coronavirus; each bat species harbours an average of 2.7 coronaviruses, mostly without showing symptoms. An increase in the number of bat species in a particular region, driven by climate change, may increase the likelihood that a coronavirus harmful to humans is present, transmitted, or evolves there.
“The fact that climate change can accelerate the transmission of wildlife pathogens to humans should be an urgent wake-up call to reduce global emissions,” says Camilo Mora, from the University of Hawai’i at Manoa, who initiated the project.
Another Russian Sputnik in the news
Last Tuesday The Lancet reported that Russia’s Sputnik V vaccine is 91.6% effective against symptomatic COVID-19 and 100% effective against severe and moderate disease, based on analysis of the vaccine’s Phase 3 trial results.
“This is great news and provides us with yet another vaccine to use in our fight against COVID,” comments LaTrobe University epidemiologist Hassan Vally. “Importantly, this vaccine looks to be extremely well-tolerated, with no serious adverse events noted, and where side effects were reported, they were mild.”
The vaccine is similar to the Oxford/AstraZeneca vaccine that will roll out in Australia. It uses a modified adenovirus vector – a virus that causes the common cold – to deliver instructions to make the COVID spike protein. Like the Oxford/AstraZeneca vaccine, the Sputnik V requires two doses.
“The early signs from the results [show] that it does produce a stronger response than the Oxford/AstraZeneca vaccine,” says Vally.
How COVID-19 took over the Diamond Princess
American research published by PNAS suggests that airborne transmission contributed substantially to the infamous COVID-19 outbreak on the Diamond Princess cruise ship.
On 20 February last year, the World Health Organization reported that more than half the world’s known cases of COVID-19 outside China were on the ship. At lease 712 of the 3,711 on board eventually contracted the disease and 14 are known to have died.
The research team modelled COVID-19 transmission aboard the ship; based on their results, they estimate that aerosols smaller than approximately 10 µm contributed to more than half of overall transmission. Both large droplets and small aerosols contributed equally to transmission before passengers were quarantined – at the Port of Yokomaha, Japan, on 4 February 2020 – while small aerosols dominated transmission post-quarantine.
“Guidance from health organisations should include a greater emphasis on controls for reducing spread by airborne transmission,” wrote the study authors, and “although our work is based on a cruise ship outbreak of COVID-19, the model approach can be applied to other indoor environments and other infectious diseases.”
SARS-CoV-2: great evader
A scientific detective story: researchers have discovered that SARS-CoV-2 evades immune responses by selectively deleting small bits of its genetic sequence.
The report published in the journal Science says that since these deletions happen in a part of the sequence that encodes for the shape of the spike protein, the formerly neutralising antibody can’t grab hold of the virus. And because the molecular “proofreader” that usually catches errors during SARS-CoV-2 replication is “blind” to fixing deletions, they become cemented into the variant’s genetic material.
“You can’t fix what’s not there,” says study senior author Paul Duprex, from the University of Pittsburgh, US. “Once it’s gone, it’s gone, and if it’s gone in an important part of the virus that the antibody ‘sees’, then it’s gone for good.”
The study was submitted as a preprint in November and the researchers have since watched this pattern play out in several variants that have rapidly spread across the globe. The variants first identified in the United Kingdom and South Africa have these sequence deletions.
“Evolution was repeating itself,” says lead author Kevin McCarthy. “By looking at this pattern, we could forecast. If it happened a few times, it was likely to happen again.”
Although the paper shows how SARS-CoV-2 is likely to escape the existing vaccines and therapeutics, it’s impossible to know at this point exactly when that might happen. Will the COVID-19 vaccines on the market today continue to offer a high level of protection for another six months? A year? Five years?
“How far these deletions erode protection is yet to be determined,” McCarthy says. “At some point, we’re going to have to start reformulating vaccines, or at least entertain that idea.”
Tony beats Kim (and Tom)
What a relief: participants in an international survey reported greater willingness to reshare a call for social distancing if the message was endorsed by well-known US immunology expert Anthony Fauci, rather than a celebrity.
A Swiss teamed reported the findings in the open-access journal PLOS ONE.
Previous research has extensively explored how to maximise the effectiveness of public health messages by altering their style and content. But relatively few studies have examined the impact of spokesperson identity on health message effectiveness, especially during crises like the COVID-19 pandemic.
The research team surveyed 12,194 people from Brazil, Italy, South Korea, Spain, Switzerland and the US in March of 2020. Respondents were asked about their willingness to share a message that encouraged social distancing, ostensibly endorsed by one of four randomly selected spokespersons: Fauci, Tom Hanks (who’d contracted COVID-19), Kim Kardashian, or a prominent government official from the survey taker’s country.
The researchers found that, across all six countries, participants reported greater willingness to share the social-distancing message if it had Fauci’s approval. The preference held true after accounting for participants’ different ages and attitudes towards social distancing.
“Identifying and empowering liked and trusted experts is a key component of effective public health communication during the ongoing pandemic, and it is likely preferable to using celebrity advocates,” wrote the authors.
Comment: Hold bungling politicians to account
Not exactly science, but still… A powerful editorial in the esteemed BMJ has asserted that politicians around the world must be held to account for mishandling the COVID-19 pandemic.
BMJ executive editor Kamran Abbasi argues that at the very least, COVID-19 might be classified as “social murder” that requires redress.
When politicians and experts say that they are willing to allow tens of thousands of premature deaths, for the sake of population immunity or in the hope of propping up the economy, is that not premeditated and reckless indifference to human life? Abbasi asks.
And when politicians wilfully neglect scientific advice, international and historical experience, and their own alarming statistics and modelling, because to act goes against their political strategy or ideology, is that lawful?
He acknowledges that any nation’s laws on political misconduct or negligence are complex, and not designed to react to unprecedented events, but says after more than two million people have died, “we must not look on impotently as elected representatives around the world remain unaccountable and unrepentant”.
“Murder is an emotive word,” he writes. “In law, it requires premeditation. Death must be deemed to be unlawful. How could “murder” apply to failures of a pandemic response? Perhaps it can’t, and never will, but it is worth considering.”
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