March 24 (UPI) – Social distance may be the most effective way to reduce the spread of the new coronavirus, a study published Tuesday in Lancet offers.
Using a flash model, researchers in Singapore found that the combined physical distance approach – isolating infected people and their families, closing schools, and practicing distance in the workplace – reduced the estimated average COVID-19 cases in the population by as much as 99.3 percent.
Researchers warned that since little is known about the transmission of the virus — they used data from SARS outbreaks 2004-05 to create their model — the real consequences of social distance are unclear.
“The results of this study provide policymakers in Singapore and other countries with evidence that they can begin to take enhanced outbreak control measures that could reduce or reduce local transmission rates in an efficient and timely deployment,” Dr. Alex R. Cook, Deputy Dean for Biostatistics and Modeling at the School of Public Health named after Sow Bitch at National University of Singapore, said in a press release.
Just one tool
On Monday, the World Health Organization warned that social distance measures were not enough to stop the spread of the new coronavirus, which infected nearly 400,000 people worldwide, including more than 43,000 in the United States.
Several cities and states across the country, including California, Illinois, and New York, as well as parts of Florida and Texas, called on “non-essential workers” to stay at home, and residents should practice social distance to stop the spread of the virus.
On Sunday, Italian officials banned all travel within the country and closed non-essential industries after more than 600 people died from COVID-19 in a 24-hour period. So far, Italy was the second suffering country during the pandemic: more than 60,000 confirmed cases and 6,000 deaths.
France and Spain have introduced similar measures as their incidence and mortality continue to rise, while Britain imposed a nationwide block on Monday after public health experts in the country forced the government to do so for several days.
“Asking people to stay home and other physical distance measures is an important way to slow the spread of the virus and gain time, but these are protective measures that won’t help us defeat,” said WHO Director General Tedros Adhan Gébrees. said at a Monday briefing.
He added that the most affected countries in the world should also be quarantined – and treated – for all confirmed cases during contact tracing and subsequent quarantine of all close contacts.
Baud rate matters
For a new study, researchers developed an individualized influenza epidemic model to assess the likelihood of transmitting COVID-19 from person to person, and then evaluate the potential impact of social distance from the outbreak.
Model parameters included how infectious a person is over time, how many people may be asymptomatic, the incubation period for the virus, and the length of hospital stay after symptoms appear.
Using this model, the researchers estimated the cumulative number of COVID-19 infections 80 days after detecting 100 cases of transmission from the community.
Given the limited knowledge about how contagious the virus is, the researchers calculated the effect of social distance based on three levels of virus transmission: low infectivity with a virus reproduction rate of 1.5; moderate and probable infection, with a breeding rate of 2.0; and high infectivity, with a breeding number of 2.5.
Key reproduction numbers were selected based on data analysis of people with COVID-19 in Wuhan, China, where the outbreak began.
Finally, they modeled the outcomes of cases based on the following scenarios: without intervention; isolation of infected persons and quarantine of their family members or quarantine; quarantine plus immediate closure of the school for two weeks; quarantine plus immediate job distance, in which half of the workforce is encouraged to work from home for two weeks; and a combination of quarantine, immediate school closure and job sharing.
They also suggested that 7.5 percent of the infected population were asymptomatic, but still contagious. At the moment, it is unclear how many people fell ill with COVID-19 but are not showing any symptoms.
Without intervention and a relatively low transmission of the virus, the researchers found that on day 80, 7.4 percent of Singapore's resident population would be infected. With moderate transmission levels, 19.3% of the Singapore population will be infected, and with high transmission, 32% of the Singapore population.
Researchers believe that combined remote intervention was most effective in reducing the number of infections at all three levels of transmission: 99.3 percent with a low level, 93 percent with a moderate and 78 percent with a high. And all intervention scenarios were more effective in reducing the incidence than lack of intervention.
Cook also warned that if remote interventions are reduced because more people are asymptomatic – and apparently do not have COVID-19 – quarantining and treating infected people "may become impossible when the number of infected people exceeds the capacity of medical facilities."
Pandemic Scenes: The World Deals With COVID-19
Mohamed Abu Dag (left) and his fiancée Israa wear masks during a photo shoot in the studio before their wedding ceremony in Khan Younis in southern Gaza on March 23. Photo by Ismael Mohamad / UPI |
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