Specific methods to control the spread of SARS-CoV-2 without resorting to blockages


Since the pandemic of coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), arose in December 2019 in the city of Wuhan, China, scientists are constantly investigating unique and new ways to control the spread of the virus without imposing intensive social restrictions.

Researchers at the Center for the Ecology of Infectious Diseases and the College of Public Health at the University of Georgia revealed alternative ways to control the spread of the pandemic without resorting to these measures.

The team introduced a conceptual framework using two mathematical models, which differ in strategy. They found that both methods were effective in controlling viral spread. However, these alternative modes may require extensive testing and work within a relatively narrow range of conditions.

Infection control measures

When the pandemic hit in March, thousands of people have already been infected with SARS-CoV-2. The virus first emerged in Wuhan City, China, in December 2019. Since then, it has spread to 192 countries and regions and infected more than 157 million people worldwide.

Early efforts to curb the transmission of SARS-CoV-2 were based on intensive measures of social exclusion, including school and workplace closures, restrictions on social gatherings, a ban on mass events, and orders to ‘welcome.

Other non-pharmaceutical measures imposed in the midst of the pandemic include active case detection, contact tracking, quarantine, insulation, regular hand washing, universal manufacturing and other personal protective measures.

While these methods are effective, most closing and closing orders have greatly affected economies.

Less extensive but effective ways

The study, published in the journal Proceedings of the Royal Society B, described alternative ways to social distancing measures that could help people adapt to the new normalcy without blockages. These include widespread testing, contact tracking, quarantine, certifications for uninfected people, and other health measures.

These alternatives can help curb the spread when combined and with the help of government and the public.

In the new conceptual framework, the team distinguished between targeted and generalized non-pharmaceutical interventions (NPIs).

Specific interventions are used to identify people in a population, based on their infection or exposure status. This means that measures are used to identify people exposed to the virus through testing, isolation, contact tracing, quarantine, symptom control, home quarantine, specific protection for high-risk people, and travel restrictions.

Meanwhile, widespread interventions are environmental or behavioral interventions that are widely accepted and practiced in a population. These include physical removal, closure of schools and workplaces, personal isolation, blocking, protection of the elderly, and the use of masks.

Comparison of interventions

The researchers worked to develop two models. One was aimed at finding infected people to reduce transmission through active case search, contact tracking and quarantine for infected people and their tracked contacts.

The next method focused on limiting exposure by providing certificates to healthy people. The team noted this when they evaluated the effectiveness of using only social distancing measures, including school closures and jobs. They found that after the first wave of pandemic, about half the population became infected.

However, when the team combined two strategies: social distancing with general interventions, viral transmission slowed, although it was not enough to ultimately defeat the virus.

The first strategy included contact tracking and quarantine measures to decrease viral transmission. The team revealed that widespread interventions would reduce cumulative cases, but are much more effective if social distancing is maintained over a long period of time.

The approach is also much more effective when widespread interventions are imposed. In addition, when the team tested the model actively seeking infection, they revealed that active case-finding should detect 95% of infected people to stop the transmission of SARS-CoV-2. When combined with non-pharmaceutical interventions, such as wearing face masks, the active cases that needed to be located were reduced to 80%.

The team also stressed the importance of contact tracking and quarantine to find active cases.

The second strategy of providing certification to healthy people can effectively reduce the size of outbreaks in two scenarios. Without widespread interventions, the waiting time for a test should be less than a week to achieve suppression.

Certification is more effective in suppressing the outbreak if widespread interventions are also implemented. The size of the outbreak can be reduced to 10 times with test validity times and waiting times of less than one month.

“These results suggest that, regardless of whether Strategy 1 or Strategy 2 approaches are adopted, a large capacity for testing is needed,” the researchers in the study concluded.

“Furthermore, success depends on the effectiveness of widespread interventions because, in the realistic scenarios we consider, they will be essential to achieving suppression,” they added.

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