How vaccination and contact isolation might interact to suppress transmission of Covid-19: a DCM study

Friston, Karl J.; Costello, Anthony; Flandin, Guillaume; Razi, Adeel

doi:10.1101/2021.01.03.20248972

Cited by 2 publications

(2 citation statements)

References 14 publications

(26 reference statements)

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“…It has become increasingly apparent that the enormous heterogeneity of exposure, susceptibility, virulence, transmission, and vaccination status play key roles in shaping the time course of the pandemic and variations between individuals, groups, communities, and countries [6,7,[92][93][94].…”

Section: Impacts Of Differential Susceptibility To Sars-cov-2 On Pandemic Modellingmentioning

confidence: 99%

The gut microbiome as a biomarker of differential susceptibility to SARS-CoV-2

Sarkar

Harty²,

Moeller

et al. 2021

Trends in Molecular Medicine

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Coronavirus disease 2019 continues to exact a devastating global toll. Ascertaining the factors underlying differential susceptibility and prognosis following viral exposure is critical to improving public health responses. We propose that gut microbes may contribute to variation in COVID-19 outcomes. We synthesise evidence for gut microbial contributions to immunity and inflammation, and associations with demographic factors affecting disease severity. We suggest mechanisms potentially underlying microbially mediated differential susceptibility to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These include gut microbiome-mediated priming of host inflammatory responses and regulation of endocrine signalling, with consequences for the cellular features exploited by SARS-CoV-2 virions. We argue that considering gut microbiome-mediated mechanisms may offer a lens for appreciating differential susceptibility to SARS-CoV-2, potentially contributing to clinical and epidemiological approaches to understanding and managing COVID-19. The host microbiome as a contributor to immunological dark matterThe emergence of SARS-CoV-2, which causes COVID-19, has triggered a pandemic with devastating global consequences. Here, we evaluate how the gut microbiome (see Glossary) may act as a driver of COVID-19 risk and contribute to COVID-19 outcomes. Several risk factors contribute to the risk of COVID-19 disease severity [1,2], and COVID-19 symptoms range from mild and transient to prolonged illness that may involve pronounced inflammation and death. The striking variation in outcomes suggests that sociodemographic or biological factors characteristic of individual hosts or populations may modify the course of SARS-CoV-2 infection. Recently, dynamic causal modelling [3] has been applied to epidemiological patterns. This approach emphasises differential susceptibility, which suggests that there are populations that are resistant or less susceptible to infection [4-7] and, by implication, populations that are more susceptible and at greater risk of virulent infection. The specific causes of differential susceptibility to SARS-CoV-2 remain under investigation and, because many of these causes are presently unobserved or 'hidden', they have been referred to as immunological dark matter [6,8]. The goals of understanding host-virus interactions and effectively treating infections both require knowledge of the factors contributing to outcome heterogeneity. Accounting for as much of this heterogeneity and differential susceptibility as possible may help clarify requisite population immunity levels to attenuate viral transmission [9] and inform development of early interventions for those who exhibit characteristics that are predictive of symptom severity.

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Section: Impacts Of Differential Susceptibility To Sars-cov-2 On Pandemic Modellingmentioning

confidence: 99%

The gut microbiome as a biomarker of differential susceptibility to SARS-CoV-2

Sarkar

Harty²,

Moeller

et al. 2021

Trends in Molecular Medicine

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, the link between case importations and the contact tracing efficiency needed to keep an outbreak under control has been little explored (Zhu et al, 2021). Finally, vaccination can clearly affect contact tracing management (Miller et al, 2020; Klinkenberg et al, 2006; Friston et al, 2021). During vaccine roll-out, we expect downsizing, or even dismantlement, of contact tracing to be possible.…”

Section: Introductionmentioning

confidence: 99%

Downsizing of contact tracing during COVID-19 vaccine roll-out

Martignoni

Renault

Baafi

et al. 2021

Preprint

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Contact tracing is a key component of successful management of COVID-19. Contacts of infected individuals are asked to quarantine, which can significantly slow down (or prevent) community spread. Contact tracing is particularly effective when infections are detected quickly (e.g., through rapid testing), when contacts are traced with high probability, when the initial number of cases is low, and when social distancing and border restrictions are in place. However, the magnitude of the individual contribution of these factors in reducing epidemic spread and the impact of vaccination in determining contact tracing outputs is not fully understood. We present a delayed differential equation model to investigate how vaccine roll-out and the relaxation of social distancing requirements affect contact tracing practises. We provide an analytical criteria to determine the minimal contact tracing efficiency (defined as the the probability of identifying and quarantining contacts of symptomatic individuals) required to keep an outbreak under control, with respect to the contact rate and vaccination status of the population. Additionally, we consider how delays in outbreak detection and increased case importation rates affect the number of contacts to be traced daily. We show that in vaccinated communities a lower contact tracing efficiency is required to avoid uncontrolled epidemic spread, and delayed outbreak detection and relaxation of border restrictions do not lead to a significantly higher risk of overwhelming contact tracing. We find that investing in testing programs, rather than increasing the contact tracing capacity, has a larger impact in determining whether an outbreak will be controllable. This is because early detection activates contact tracing, which will slow, and eventually reverse exponential growth, while the contact tracing capacity is a threshold that will easily become overwhelmed if exponential growth is not curbed. Finally, we evaluate quarantine effectiveness during vaccine roll-out, by considering the proportion of people that will develop an infection while in isolation in relation to the vaccination status of the population and for different viral variants. We show that quarantine effectiveness decreases with increasing proportion of fully vaccinated individuals, and increases in the presence of more transmissible variants. These results suggest that a cost-effective approach during vaccine roll-out is to establish different quarantine rules for vaccinated and unvaccinated individuals, where rules should depend on viral trans-missibility. Altogether, our study provides quantitative information for contact tracing downsizing during vaccine roll-out, to guide COVID-19 exit strategies.

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How vaccination and contact isolation might interact to suppress transmission of Covid-19: a DCM study

Cited by 2 publications

References 14 publications

The gut microbiome as a biomarker of differential susceptibility to SARS-CoV-2

The gut microbiome as a biomarker of differential susceptibility to SARS-CoV-2

Downsizing of contact tracing during COVID-19 vaccine roll-out

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