And two separate studies point to the Huanan markets in Wuhan as the origin of SARS-CoV-2.
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28 February
- Monoclonal antibody combination approved for pre-exposure prophylaxis in immunocompromised people.
- Two studies point to Huanan seafood market as origin of SARS-CoV-2.
- Molnupiravir recommended for PBS listing to prevent severe disease.
- European Medicines Agency recommends Pfizer boosters for over-12s.
Immunocompromised people who are unable to get vaccinated against covid can now get access to pre-exposure prophylaxis in the form of monoclonal antibody combination therapy of tixagevimab and cilgavimab.
The TGA has granted provisional approval for the combination to be used in people who have not been exposed to the virus but who cannot get vaccinated either because of moderate to severe immune compromise or because of a severe reaction to a previous covid vaccine.
The approval is based on clinical trial data suggesting that the two-dose treatment significantly reduces the risk of symptomatic covid for at least six months.
The Huanan Wholesale Seafood Market is the most likely epicentre for the spread of SARS-CoV-2, based on the clustering of the early cases and the detection of the virus in environmental samples taken from the market.
That’s the latest from two teams of scientists who have been investigating the origins of the pandemic, and who each published papers on non-peer-reviewed preprint servers last week.
The first paper, published on ResearchSquare, reported on the study of 923 environmental samples – from sewerage wells, drains, surfaces and the ground, for example – and 457 animal samples including stray animals and faeces, collected in and around the market between 1 January and 2 March 2020.
Nearly 8% of the samples collected inside the market itself tested positive for the same strain of SARS-CoV-2 associated with the earliest cases of covid. The majority of positive samples came from the particular area of the market where live animals were sold.
A second paper, published on Zenodo, used epidemiological, genomic, commercial, photographic, location, social mobility and survey data to investigate the market as the possible origin of the virus.
This showed that the early cases of covid in Wuhan were clustered closely around the Huanan market and that the animals sold at the markets included several that are susceptible to SARS-CoV-2 infection, in particular raccoon dogs.
The authors of this study also commented that previous research looking for a potential animal host of the virus – but which came up empty-handed – had either sampled animals that weren’t susceptible to the virus, sampled dead animals that weren’t likely to still have virus, or sampled animals from outside Wuhan.
“Not a single raccoon dog from the Huanan market, live or dead, was reportedly tested for SARS-CoV-2, nor were those from the wild populations or the farms in Hubei that supplied them to the Huanan market,” the authors wrote.
They also emphasised that the majority of environmental samples came from the area of the market associated with live wild animal sales.
“We arguably now have as clear a picture of the zoonotic origin of SARS-CoV-2 as for any of the other eight coronaviruses known to infect humans,” they wrote.
The covid antiviral molnupiravir has been recommended for PBS listing for treating covid in people with mild to moderate disease but risk factors for severe disease.
The Pharmaceutical Benefits Advisory Committee recommended the listing for people aged 65 and over with two risk factors for severe disease, aged 75 and over with one risk factor for severe disease, people with moderate to severe immunocompromise, and Aboriginal or Torres Strait Islander people aged over 50 with two risk factors for severe disease.
The European Medicines Agency is now recommending approval of Pfizer boosters for children aged 12 and over.
The recommendation is based on clinical trial of boosters in those aged 16 and over, as well as real-world data from Israel where boosters are already being rolled out in younger children.
