Coronavirus Research Tracking - 23 October
New Zealand cases & response, brief contacts, nanodecoys, rapid tests, remdesivir trials, vaccination attitudes
This week’s Research Tracker is a very mixed bag. We highlight papers that describe New Zealand’s cases and compare its pandemic response, infections from brief contacts, new infection routes and decoy traps, rapid diagnostic tests, controlled trials and observational studies, attitudes to vaccines, and Covid-19 myths.
The Research Tracker is prepared by Dr Robert Hickson for the Science Media Centre.
New Zealand’s epidemiology profile
A summary of New Zealand Covid-19 cases between February and May is described in The Lancet Public Health. Of the 1503 reported cases 95 (6·3%) were admitted to hospital and 22 (1·5%) died. Just under half (47%) of the cases were linked to 34 outbreaks. Only 25 (1.7%) asymptomatic cases were detected.
Comparison of Taiwan’s and New Zealand’s pandemic responses
Taiwan’s more proactive response to the pandemic is compared to New Zealand’s reactive response in a paper published in The Lancet Regional Health: Western Pacific. Taiwan’s lower number of cases and avoidance of stringent lockdowns is attributed, in part, to having good communicable diseases infrastructure in place and pandemic planning. This led to more rapid and systematic introduction of control measures.
Short but repeated contacts may occasionally result in infection
A CDC case note reports that a US prison guard appears to have become infected after a series of short (under one minute) close interactions (within 2 metres) with several then asymptomatic prisoners. Both the guard and prisoners wore masks. Twelve other guards who also had close but short contacts with some of these prisoners did not become infected.
What is known about transmission
A clear and concise overview of the dynamics of SARS-CoV-2 spread was published in Science.
Another cell receptor may enable viral infection
The ACE2 receptor is recognised as an important means for SARS-CoV-2 to infect human cells. Two papers, both in Science, describe evidence that another cell receptor - Neuropilin-1 - is involved helping SARS-CoV-2 enter into cells.
Knocking out Neuropilin-1 in cell cultures resulted in lower infectivity.
Examining cells from people who died from Covid-19 revealed that the virus was present in cells that express high levels Neuropilin-1 but low levels of ACE2. A monoclonal antibody that targets Neuropilin-1 also reduced SARS-CoV-2 infection in cell cultures.
Nanodecoys
Drugs or antibodies are typically used to reduce infection of cells. An alternative approach involves providing a more attractive receptor for the virus to bind too.
A paper in the Proceedings of the National Academy of Sciences describes the creation of nanoparticles formed from cellular membranes carrying the ACE2 receptor and cytokine receptors. Preliminary tests on cell cultures and mice demonstrated that they bind the virus and reduce inflammatory cytokine levels. Further testing and development is required.
Another research group has developed a soluble ACE2 protein that can bind with the spike protein from a range of SARS-associated viruses. The study has not yet been peer reviewed.
Two large trials give different results for effectiveness of remdesivir
The final report of a US NIH randomised controlled trial of remdesivir was published in the New England Journal of Medicine. It concluded that remdesivir reduced median time of hospital stay for patients from 15 down to 10 days. There was also evidence that those treated with remdesivir had less severe lung damage. Greater benefit of remdesivir was seen for those with less severe disease.
Preliminary results of the World Health Organisations SOLIDARITY clinical trial have been released as a pre-print paper. This study of hospitalised patients considered the effect on mortality of remdesivir, hydroxychloroquine, lopinavir and interferon-β1. None improved patient survival. It also found that none of the treatments reduced the length of hospital stay or delayed the need for mechanical ventilation.
Differences between the remdesivir results of the two trials could in part be due to greater heterogeneity of patients in the global SOLIDARITY trial, or other differences in how the trials were run. Other research has shown that interferon is more effective if given earlier in disease progression.
Observational studies vs controlled trials
An article in the Proceedings of the National Academy of Sciences discusses the rapid growth of observational studies to determine effective Covid-19 treatments. These review medical records and “real world” data sources rather than conducting randomised trials. While observational studies are useful if well designed and executed, the article notes that many of the published ones are of poor quality and misleading, or in some cases dangerous.
Rapid tests for infection
A variety of new rapid tests for the virus are being developed. Most still require further refinement.
An imaging test that uses neural networks to identify different types of viruses has been developed. Once samples have been prepared identification can take as little as five minutes for clinical samples, although accuracy is currently under 80%. The method is described in a pre-print paper.
A CRISPR-based test that can detect viral RNA using fluorescence and a mobile phone camera can provide results in under 30 minutes in a proof-of-concept study (not yet peer reviewed).
A perspective published in the New England Journal of Medicine notes the need for better surveillance tests rather than clinical tests. The latter are very sensitive, but slow and expensive. They are used to confirm infection. Lower cost, quicker and somewhat less sensitive surveillance tests are needed to complement clinical testing to identify people who are infectious not just infected.
Global survey vaccine acceptance
The results of surveys in 19 countries about attitudes to Covid-19 vaccines was published in Nature Medicine. There was considerable variation between countries, with China, South Korea and Singapore having the highest levels of acceptance. Those who said that they trusted their government were more likely to accept a vaccine than those who said that they did not. Numbers surveyed in each country were relatively small (700-800).
Persistent Covid-19 myths
Eight myths about Covid-19, and reasons why they may be believed, are described in Scientific American.