Coronastream: the Swedish strategy, artificial intelligence-assisted testing and strategies to reopen travel
Posted on September 9, 2020 by Dr Tim Inglis
In this special blog series, medical microbiologists led by Dr Tim Inglis summarise some of the research that will be essential to inform COVID-19 countermeasures. Find out more about the project in Dr Inglis' Editorial 'Logic in the time of coronavirus', published in the Journal of Medical Microbiology.
Life in Fortress Western Australia is cushioned from the more brutal effects of the COVID-19 pandemic, seen recently on the other side of the country. Melbourne and regional centres in Victoria have had a rough time of it. They are still not completely clear of this most recent wave of cases. Healthcare workers there have been hit hard by occupationally acquired infections. Meanwhile, in Western Australia, our fly-in, fly-out mobile laboratory has been in action. It will be used again whenever a decisive laboratory response is needed for outbreak investigations, such as when the state border controls are lifted. Those controls look set to continue until the end of the year, much to the chagrin of a lot of Australian-rules football supporters and one wealthy industrialist, who look to Sweden's initial laissez-faire approach as justification for relaxing what they consider to be excessive public health intervention.
Congruence: clinico-pathological features
Artificial intelligence-assisted loop mediated isothermal amplification (AI-LAMP) for rapid detection of SARS-CoV-2
SARS-CoV-2 tests have come to the fore as we struggle to find a way out of the current pandemic stalemate. It is becoming clear that we need tests that deliver actionable results at or close to the point of care, as distinct from the highly centralised, industrial-scale PCR assays used by many public health laboratories.
In their article, Rohaim and colleagues describe a loop-mediated isothermal amplification (LAMP) assay for SARS-CoV-2 suitable for use in a hand-held device, augmented by automated imaging processed with artificial intelligence methods. Using the RNA-dependent RNA polymerase gene as its target, test performance in this preliminary study was superior to quantitative reverse transcriptase PCR. LAMP has potential application in resource-limited settings.
Seroprevalence of SARS-CoV-2 among frontline health care personnel in a multistate hospital network - 13 academic medical centers, April-June 2020
The higher prevalence of COVID-19 among Australian workers looking after patients in the recent Victorian resurgence has brought the vulnerability of healthcare workers into focus. This study from a developed country with a much higher case load highlights the issues facing those in the frontline of health care. Six percent of 3,248 study participants have a positive antibody test, with per-hospital seroprevalence ranging from 0.8-31.2%. Lower seroprevalence was observed in staff using surgical masks, N95 or powered respirators (PAPR) while working with patients. Over a quarter of seropositive workers reported no COVID symptoms, representing a potential undetectable transmission risk.
During the early stages of the COVID-19 pandemic, Swedish authorities predicted that naturally acquired herd immunity would be enough to keep the infection under control. Lindstrom's paper discusses the philosophy underlying the public health response to COVID-19 and puts Sweden's post-materialist ethos under the microscope. He links Sweden's postmodernism with overconfidence in a combination of herd immunity, individual responsibility and evidence-based medicine. Also singled out for criticism are opposition to authority, rationality and science and a stance against the values of older generations. For those of us witnessing sustained attacks on restricted movement across the borders between Australian states, we can but hope that Sweden's experience will act as a warning to others.
Cumulative dissonance: pathogenesis & pathophysiology
In this study into the role of immunopathology in the pathogenesis of pulmonary disease in COVID, profound changes were found in a heterogeneous group of circulating T lymphocytes (MAIT, γδT, and iNKT cells). Activated unconventional T cells were also found in the airways of patients with COVID-19. A CD69 marker on circulating iNKT and MAIT cells predicted the clinical course and severity of COVID-19.
Curtailment: therapeutic and preventive countermeasures
As countries consider how to re-open international travel, strengthened control measures at points of entry will be needed. The optimal timing and frequency of testing, and the relationship with quarantine, is a complex calculus with public health, economic and political ramifications. Dickens and colleagues considered six approaches to reduce COVID importation risk. The best results were for testing all travellers, isolating those who test positive and allowing entry at seven days for those who test negative. For the top exporting countries, an 88.2% reduction in secondary cases was expected through this approach with the seven-day isolation of people with a positive test, and 92.1% if isolation was 14 day. The combination of SARS-CoV-2 testing of all international travellers and selective quarantine appears to produce the best outcomes of the approaches considered in this study.
This useful analysis of 1,022 participants in overnight school camps in the USA, found no secondary transmission of SARS-CoV-2 following the introduction of non-pharmaceutical interventions. Participants came from 41 states, one territory and six international locations. The majority were tested before arrival at their camp and did not include a small group who were positive and completed quarantine before the camp. There were four asymptomatic participants who delayed their participation after returning a positive test result. Three further asymptomatic participants were detected on re-testing of previous negative subjects around one week after arrival at camp.