BAKU, Azerbaijan, Mar. 31
The fraction of undocumented but infectious cases is a critical epidemiological characteristic that modulates the pandemic potential of novel coronavirus (COVID-19), Trend reports with reference to a research published by American Association for the Advancement of Science.
The research said that these undocumented infections often experience mild, limited or no symptoms and hence go unrecognized, and, depending on their contagiousness and numbers, can expose a far greater portion of the population to virus than would otherwise occur.
The research’s findings indicate that a large proportion of COVID-19 infections were undocumented prior to the implementation of travel restrictions and other heightened control measures in China on Jan. 23, and that a large proportion of the total force of infection was mediated through these undocumented infections.
“This high proportion of undocumented infections, many of whom were likely not severely symptomatic, appears to have facilitated the rapid spread of the virus throughout China. Our findings also indicate that a radical increase in the identification and isolation of currently undocumented infections would be needed to fully control SARS-CoV2. Increased news coverage and awareness of the virus in the general population have already likely prompted increased rates of seeking medical care for respiratory symptoms. In addition, awareness among healthcare providers, public health officials and the availability of viral identification assays suggest that capacity for identifying previously missed infections has increased,” the research said.
Further, the information said, general population and government response efforts have increased the use of face masks, restricted travel, delayed school reopening and isolated suspected persons, all of which could additionally slow the spread of SARS-CoV2.
Combined, these measures are expected to increase reporting rates, reduce the proportion of undocumented infections, and decrease the growth and spread of infection, the research results said.
“While the data and findings presented here indicate that travel restrictions and control measures have reduced SARS-CoV2 transmission considerably, whether these controls are sufficient for reducing the length of time needed to eliminate the disease locally and prevent a rebound outbreak once control measures are relaxed is unclear. Further, similar control measures and travel restrictions would have to be implemented outside China to prevent reintroduction of the virus,” the research said.
The research said that the key findings, that 86 percent of infections went undocumented and that, per person, these undocumented infections were 55 percent as contagious as documented infections, could shift in other countries with different control, surveillance and reporting practices.
“Our findings underscore the seriousness and pandemic potential of SARS-CoV2. The 2009 H1N1 pandemic influenza virus also caused many mild cases, quickly spread globally, and eventually became endemic. Presently, there are four, endemic, coronavirus strains currently circulating in human population. If the novel coronavirus follows the pattern of 2009 H1N1 pandemic influenza, it will also spread globally and become a fifth endemic coronavirus within the human population,” the research said.
The outbreak in the Chinese city of Wuhan - which is an international transport hub - began at a fish market in late December 2019. The number of people killed by the disease has surpassed 37,800. Over 786,200 people have been confirmed as infected. Meanwhile, over 166,000 people have reportedly recovered.
Some sources claim the coronavirus outbreak started as early as November 2019.
The World Health Organization (WHO) declared COVID-19 a pandemic on March 11.