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The 2019 coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected more than 221 million people and caused more than 4.57 million deaths . The implementation of non-pharmaceutical interventions (NPIs) such as social distancing, wearing masks, lockdowns and travel bans helped control the first wave of the COVID-19 pandemic.
Study: How control and relaxation interventions and viral mutations influence the resurgence of COVID-19. Image Credit: DisobeyArt / Shutterstock
Despite these successful interventions during the first wave, the COVID-19 epidemic returned stronger during the second wave in many countries. The effects of controlling these interventions and their relaxations on COVID-19 and its resurgence are unclear. Coupled with the rapid mutations of the virus, the dynamic epidemiological processes of COVID-19 become even more complicated.
A recent study available on the preprint server medRxiv* addresses these effects in detail to develop a deeper understanding of their influence on the COVID-19 resurgence by developing a dynamic event-based SEIR (susceptible-exposed-infectious-recovered) model, SPEIQRD.
The researchers applied the model during the first and second waves in 2020 in Germany, France and Italy as a case study. In the absence of sufficient vaccination, herd immunity, and effective pharmaceutical antiviral treatments, they found that early or rapid relaxation of interventions (including restrictions on public activity) leads to a resurgence of COVID-19. Importantly, this study is the first attempt to simulate the impact of viral mutations (such as delta and lambda) with a 20-100% increase in transmissibility on second waves and resurgences of infections and effect of control and relaxation interventions.
Focusing on specific aspects and a “qualitative to descriptive” analysis of the second waves of the pandemic, the researchers divided the study into four main questions.
A pre-printed version of the study is available on the website medRxiv* server while the article is subject to peer review.
How do epidemiological attributes change during wave 1 to wave 2 in different countries?
To understand this, the researchers quantified and analyzed epidemiological attributes such as infection rate, incubation rate, quarantine rate, recovery rate, death rate, and then behaviors and patterns between patients. waves in Germany, France and Italy. They concluded that weaker interventions combined with stronger deconfinement activities were associated with the second wave in these countries.
How does the different severity, number and timing of interventions individually and cumulatively affect the trends of the two waves?
These effects of the severity, number and timing of interventions and social activities on behaviors and trends of two waves characterize the dynamic processes of evolution from the first to the second wave and their sensitivity. They deduced the individual and cumulative impact of control and relaxation interventions (early / late, plus / minus), which affected the daily cases of each wave. The researchers demonstrated the different dynamics and trends in each country, the control and relaxation events that generate opposite effects – either suppressing or accelerating the COVID-19 curves, and the inappropriate relaxations that may have contributed to the wave differences. and the resurgence of COVID-19 in all three countries.
How would the different control and relaxation intervention strategies influence the 30-day trends following the second waves?
In addition, the researchers simulated different scenarios to assess how intervention control and relaxation strategies influence the trends for the next 30 days following the second waves. The scenarios reflected different response strategies and behaviors of governments, individuals and societies to the second waves, such as the application or relaxation of interventions and restrictions on socio-economic activities to varying degrees. They concluded that it would not be safe to reopen the company on a large scale at the end of the second wave (i.e. early December 2020) – as there would still be a considerable number of infected individuals.
How would more infectious virus mutants influence second waves during hard or soft interventions?
Again, they simulated and evaluated the influence of more infectious mutant viruses (such as delta and lambda) with different levels of transmissibility on the second waves when the actual strong and weak interventions are performed from their first and second waves. . Then they predicted the next trends in cases within 30 days of the second wave if different levels of transmissibility of the mutant viruses emerged. They have shown an overwhelming result of highly infectious coronavirus mutations in the community when no effective control measures are adopted and vaccination is insufficient.
The researchers also demonstrated that their model predicts the future well. This study focuses on (1) the description of the epidemiological characteristics of the second waves, (2) the comparison of the epidemiological attributes of the first and second waves, and (3) the prediction of the resurgence, including the impact of external factors.
The results and analyzes of this study provide evidence for governments and policymakers to systematically manage the pandemic and outbreaks. The research is also useful in the growing debates on elimination (zero COVID, such as practices undertaken in countries like China), eradication or suppression (“living with the virus” to an acceptable level, such as companies in countries like the UK and US) and upon full reopening, are reasonable in practice, the researchers write.
*Important Notice
medRxiv publishes preliminary scientific reports which are not peer reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.
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