20 research outputs found
Potential severity, mitigation, and control of Omicron waves depending on pre-existing immunity and immune evasion
Risk assessment of novel coronavirus COVID-19 outbreaks outside China
We developed a computational tool to assess the risks of novel coronavirus outbreaks outside of China. We estimate the dependence of the risk of a major outbreak in a country from imported cases on key parameters such as: (i) the evolution of the cumulative number of cases in mainland China outside the closed areas; (ii) the connectivity of the destination country with China, including baseline travel frequencies, the effect of travel restrictions, and the efficacy of entry screening at destination; and (iii) the efficacy of control measures in the destination country (expressed by the local reproduction number Rloc ). We found that in countries with low connectivity to China but with relatively high Rloc , the most beneficial control measure to reduce the risk of outbreaks is a further reduction in their importation number either by entry screening or travel restrictions. Countries with high connectivity but low Rloc benefit the most from policies that further reduce Rloc . Countries in the middle should consider a combination of such policies. Risk assessments were illustrated for selected groups of countries from America, Asia, and Europe. We investigated how their risks depend on those parameters, and how the risk is increasing in time as the number of cases in China is growing
Potential severity, mitigation, and control of Omicron waves depending on pre-existing immunity and immune evasion
In Silico Evaluation of Paxlovid’s Pharmacometrics for SARS-CoV-2: A Multiscale Approach
Paxlovid is a promising, orally bioavailable novel drug for SARS-CoV-2 with excellent safety profiles. Our main goal here is to explore the pharmacometric features of this new antiviral. To provide a detailed assessment of Paxlovid, we propose a hybrid multiscale mathematical approach. We demonstrate that the results of the present in silico evaluation match the clinical expectations remarkably well: on the one hand, our computations successfully replicate the outcome of an actual in vitro experiment; on the other hand, we verify both the sufficiency and the necessity of Paxlovid’s two main components (nirmatrelvir and ritonavir) for a simplified in vivo case. Moreover, in the simulated context of our computational framework, we visualize the importance of early interventions and identify the time window where a unit-length delay causes the highest level of tissue damage. Finally, the results’ sensitivity to the diffusion coefficient of the virus is explored in detail
Dynamics of an SIRWS model with waning of immunity and varying immune boosting period
SIRS models capture transmission dynamics of infectious diseases for which
immunity is not lifelong. Extending these models by a W compartment for
individuals with waning immunity, the boosting of the immune system upon
repeated exposure may be incorporated. Previous analyses assumed identical
waning rates from R to W and from W to S. This implicitly assumes equal length
for the period of full immunity and of waned immunity. We relax this
restriction, and allow an asymmetric partitioning of the total immune period.
Stability switches of the endemic equilibrium are investigated with a
combination of analytic and numerical tools. Then, continuation methods are
applied to track bifurcations along the equilibrium branch. We find rich
dynamics: Hopf bifurcations, endemic double bubbles, and regions of
bistability. Our results highlight that the length of the period in which
waning immunity can be boosted is a crucial parameter significantly influencing
long term epidemiological dynamics