For COVID-19 Surveillance, Test Frequency and Turnaround Time Are Paramount, Modeling Suggests Speed of test results and frequency of testing are paramount for effective COVID-19 surveillance, suggests a new study that modeled trade-offs in test sensitivity, test frequency, and sample-to-answer reporting time, in select scenarios. Test sensitivity is secondary to these factors in the scenarios studied, the authors say. “If the availability of point-of-care or self-administered screening tests leads to faster turnaround time or more frequent testing, our results suggest that they would have high epidemiological value,” Daniel Larremore and colleagues write. Because SARS-CoV-2 can spread from individuals with pre-symptomatic, symptomatic, and asymptomatic infections, diagnosis and isolation based on symptoms alone won’t prevent spread. Rather, robust population screening, for which virus testing is often central, will be critical. However, related surveillance testing programs must make concrete choices, including: What are the tradeoffs between cost, frequency, test sensitivity, and the speed with which diagnoses can be returned? To evaluate this, Larremore and colleagues modeled how changing viral load (different levels of infectiousness) impacted the ability of an assay, or test, to diagnose infection. They calculated what percentage of these people’s total infectiousness would be removed by screening and isolation, using different testing approaches. They also evaluated the impact of surveillance at the population level using two epidemiological models that incorporated viral load dynamics, one of which mimicked aspects of the contact structure of New York City. Across their analyses of individuals and populations, the inclusion of viral load in surveillance modeling revealed that the limits in detection abilities of tests mattered less than previously thought, the authors say. But delays in returning diagnoses were highly impactful, with even one-day delays between sample and answer undercutting otherwise impactful surveillance plans. As well, the frequency of surveillance testing plays a crucial role, the authors say. They note that communities vary in their transmission dynamics, so specific strategies for successful population screening will depend on the current community infection prevalence and transmission rate in a given location. They also identify other limitations in their study. Still, they say their findings could aid some groups planning societal reopening, refocusing their efforts on rapid turnaround times instead of highly sensitive tests. They may also inform regulatory agencies and test manufacturers about the importance of developing and approving such tests, optimized for surveillance (as opposed to clinical diagnosis).

Researchers at Orygen and La Trobe University in Melbourne, Australia have completed a rapid review of contemporary epidemic and pandemic research to assess the potential impact of COVID-19 on people with psychosis.

The review, published online ahead of print in Schizophrenia Research, found an increase in the prevalence of psychosis as a result of COVID-19 would likely be associated with viral exposure, pre-existing vulnerability and psychosocial stress. The review also suggested that people with psychosis may present a major challenge and potential infection control risk to clinical teams working with them.

Orygen research fellow and co-lead author on the study, Dr Ellie Brown looked at published research on viruses such as MERS, SARS, swine influenza and other influenzas that have occurred in the past 20 years, to examine if there was any connection to how these viruses might impact people with psychosis.

“COVID-19 is a very stressful experience for everyone, particularly those with complex mental health needs,” Dr Brown said. “We know that psychosis, and first episodes of psychosis, are commonly triggered by substantial psychosocial stresses. In the context of COVID-19, this could include stress relating to isolation and having to potentially remain within challenging family situations.

“People with psychosis are a population that are particularly vulnerable in the current COVID-19 pandemic and their needs are often overlooked.

“This research shows that their thoughts around contamination, and their understanding around concepts such as physical distancing may be different from the wider population.”

Co-lead author of the research, Professor Richard Gray of La Trobe University said another important finding from the research was that psychotic symptoms, such as hearing voices, may occur in a small number of people with COVID-19.

“Maintaining infection control procedures when people are psychotic is challenging,” Professor Gray said. “In order for them not to become potential transmitters of the virus, clinicians and service providers may benefit from specific infection control advice to mitigate any transmission risk.”

Dr Brown said that although mental health disorders such as depression and anxiety were important to focus on during the COVID-19 pandemic, the community needed to be aware that the smaller but more severe spectrum of mental health conditions could be impacted as well.

Professor Gray agreed. “This is a group that’s probably going to need more support, with isolation, physical distancing, hand washing etc, and clinicians may be the ones who need to be thinking and working on this to assist this vulnerable population,” he said.

Simple measures can help reduce the spread and severity of infection among those living with people who have covid-19, say experts in The BMJ today.  

Professor Paul Little at the University of Southampton and colleagues say people caring for household members who are unwell should be encouraged to take measures such as handwashing and cleaning, avoiding sharing rooms and surfaces, managing incoming deliveries, and ventilating rooms to limit transmission.

Evidence suggests that “viral load” – the number of viral particles that start the infection off – is likely to be important for covid-19, they explain. In general, the higher the viral load the easier it is for the infection to get hold and the more severe the infection is.

But while government policy is aimed at reducing transmission of covid-19 between family units, less attention has been given to transmission between family members, they write. 

One intervention that could be rapidly disseminated in this pandemic and that has been shown to reduce incidence, transmission, and severity of seasonal flu is ‘Germ Defence’ – a website that provides advice on infection control measures and helps users think about when and how to carry out key infection control behaviours.

It is not practical for people at home to use the same methods that are used to protect hospital workers from infection from patients, explain the authors. But there are many other ways to try to reduce exposure to virus in the home, and they’re explained in GermDefence.org. 

Originally developed during the H1N1 pandemic, the website is now being adapted for covid-19 and is set to be rolled out nationally and internationally to help limit transmission of covid-19 as well as the other viruses that are still causing the majority of respiratory illnesses in the current pandemic, they say.

Use of such behavioural interventions “could support public health advice to improve infection control in families,” they conclude.