Simulating transmission dynamics of SARS-CoV-2 Omicron variant

In a latest preprint research posted to the medRxiv* server, a crew of researchers simulated the emergence of Omicron, a novel extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concern (VOC), in a normal European setting utilizing an individual-based transmission mannequin.

Study: Assessing impact of Omicron on SARS-CoV-2 dynamics and public health burden. Image Credit: NStafeeva/ShutterstockResearch: Assessing impression of Omicron on SARS-CoV-2 dynamics and public well being burden. Picture Credit score: NStafeeva/Shutterstock

Quickly after its emergence, Omicron coronavirus illness 2019 (COVID-19) instances occurred in 24 nations, with infections additionally occurring in beforehand contaminated and double vaccinated people. In such a situation, it’s crucial to find out the potential for Omicron to change into the brand new dominant VOC relative to the Delta variant. 

The research

A number of mathematical fashions have been used to signify SARS-CoV-2 transmission dynamics. The authors of this research developed OpenCOVID, an individual-based mannequin of SARS-CoV-2 transmission, which included seasonality patterns, waning immunity profiles, vaccination, and NPI methods, and different properties for a number of variants. Utilizing this mannequin, they simulated the interaction of Omicron’s potential mixtures of infectivity, severity, and immune evasion properties to grasp the potential scope of Omicron’s public well being burden – i.e., new SARS-CoV-2 infections, ICU occupancy, and coronavirus illness 2019 (COVID-19) associated deaths – in a vaccinated inhabitants. 

They utilized this mannequin to signify normal European settings as a result of, regardless of excessive vaccination charges, these areas are once more beneath SARS-CoV-2 transmission risk for a number of causes:

  1. indoor contact is growing because of the winter season,
  2. the immunity of probably the most weak inhabitants is waning, and
  3.  the fatigue of COVID-19 restrictions has led to elevated contacts. 


The researchers recognized infectivity as the principle driver, adopted by immune evasion, with negligible impact from growing severity, behind Omicron’s potential dominance, over the Delta variant. In one of many simulated eventualities the place Omicron would have attained the next immune evasion capability of fifty%, the infectivity of 1.5, and severity relative to Delta, it turned dominant inside two months, extremely impacting the general public well being burden.

Nonetheless, there exists a variety of infectivity and immune evasion properties for which Omicron will change into dominant inside two to a few months, leading to a excessive to very excessive impression on the general public well being burden. 

Even when Omicron attains infectivity and severity much like Delta, the outcomes present that it will not result in excessive peak ICU occupancy beneath the belief of expanded vaccination which incorporates third vaccine doses for adults six months after the second dose and vaccinating 5-11-year-olds. 

The advantages of expanded vaccination can be obvious in eventualities the place Delta stays dominant. Nonetheless, when Omicron turns into dominant, expanded vaccination would work when Omicron’s potential immune evasion can be low.

The simulations additionally predicted that expanded vaccination can be inadequate to stop excessive peak ICU occupancy when Omicron’s potential immune-evading property can be >75%. In such a scenario, extra measures equivalent to bodily distancing, new remedies, and next-generation vaccines will show useful. Within the absence of those measures, Omicron’s potential severity can have negligible affect on new infections; nonetheless, it will closely affect future mortality.


The research findings present essential quantitative steerage to decision-makers at a vital time in order that they will make required changes and reply to the impression of Omicron’s future potential dominance on public well being.

To organize for future eventualities, when new VOCs emerge and change into predominant, the authors suggest improvising vaccines towards SARS-CoV-2 to extend their effectiveness towards present or future viral mutations. As well as, steady enhancements in checks and assays might elucidate immune evasion properties of latest VOCs to grasp the chance for elevated infectivity and/or severity.

The authors additionally emphasize the significance of increasing vaccination with booster doses and handle points equivalent to the worldwide inequity of vaccine entry leading to low vaccination charges in some nations amid the emergence of latest VOCs. Additionally they advocate for continued genomic and inhabitants epidemiological surveillance of Omicron and different VOCs which will come up sooner or later.

As extra data on Omicron or different future SARS-CoV-2 VOCs change into out there, these analyses might assist interpret the potential dominance and ensuing public well being burden of these VOCs.

*Necessary discover

medRxiv publishes preliminary scientific experiences that aren’t peer-reviewed and, due to this fact, shouldn’t be thought to be conclusive, information medical apply/health-related conduct, or handled as established data.

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