Undocumented infection drives Covid-19 spread

Tuesday March 17th, 2020

The failure to screen and diagnose for the new coronavirus was a key cause of its early rapid spread across China, according to an analysis published last night.

Researchers said that travel restrictions introduced in late January were then successful in stopping further transmission.

According to the analysis, by Chinese researchers and published in Science, undocumented infections were 55% as contagious as documented infections. Until 23 January, 86% of cases of disease were not identified, they estimate.

However a second study in the journal says that travel restrictions have only "modest" impact on spread.

They are the latest of a welter of studies released by journals as the world grapples to understand the Covid-19 pandemic.

Frontiers in Pediatrics reports that four babies born in a hospital in Wuhan, the epicentre of the novel coronavirus outbreak in China, did not show signs of infection and remain healthy today.

This study, published yesterday (16 March 2020), backs up the findings of earlier research in China that confirmed mothers infected with COVID-19 during pregnancy did not infect their babies.

Study co-author Dr Yalan Liu, of Huazhong University of Science and Technology, said none of the infants developed any serious symptoms associated with COVID-19, but they were all initially isolated in neonatal intensive care units and fed formula.

Three of the four tested negative for the respiratory infection following a throat swab, while the fourth child's mother declined permission for the test.

In the previous retrospective study on nine pregnant mothers infected with COVID-19, all nine births were done by caesarean section. In this study, three of the four births were delivered via C-section.

"To avoid infections caused by perinatal and postnatal transmission, our obstetricians think that C-section may be safer," Dr Liu said. "Only one pregnant mother adopted vaginal delivery because of the onset of the labour process. The baby was normal. Maybe vaginal delivery is OK. It needs further study."

A second study, by the University of East Anglia (UEA), London School of Hygiene & Tropical Medicine (LSHTM) and Samson Institute for Ageing Research (SIFAR), Cape Town, warns that current guidance on coronavirus “largely ignores” the implications for public health and clinical responses in light of those most at risk.

Writing in the BMJ, the global experts call for an age perspective to be included explicitly in national and global planning on COVID-19, as well as the urgent formation of an expert group on older people to support with guidance and response to the virus.

Professors Peter Lloyd-Sherlock of UEA, Shah Ebrahim and Martin McKee of LSHTM, and Dr Leon Geffen at SIFAR, write that the largest numbers of deaths will occur among older people in low and middle-income countries (LMICs).

Prof Lloyd-Sherlock, professor of social policy and international development at UEA, said: “The global response to coronavirus must be directed towards those groups who will face the most devastating consequences. So far, this has not happened. We are facing an unprecedented and enormous wave of mortality among older people in these countries.”

The risk of infection for older people in LMICs is high because living arrangements are often cramped and overcrowded, while increasing numbers live in nursing homes or similar facilities, where conditions are often poor and regulation weak.

The researchers say social distancing policies must consider the already precarious existence of many older people, particularly those living alone or dependent on others for care and support. These people may face barriers to obtaining food and other essential supplies if quarantine conditions become more widespread.

A third report by researchers from CAS, a division of the American Chemical Society, provides an overview in ACS Central Science of published scientific information on potential therapeutic agents and vaccines for the virus.

Led by Cynthia Liu, the research team analysed the published scientific data on SARS-CoV-2 and related coronaviruses, as well as patents associated with human coronaviruses.

From the last week of 2019 until 1 March 2020, more than 500 journal articles related to the virus were published electronically or in print, with numbers steadily increasing week-by-week.

Topics included clinical manifestations, treatment regimens, viral structure and mechanisms, antiviral agents, and diagnostics.

More than 500 patents have been issued for vaccines and for therapeutic agents that could help prevent or treat coronavirus infections. Because SARS-CoV-2 is similar to other coronaviruses, such as SARS-CoV-1 and MERS-CoV, the researchers highlighted therapies previously explored for these other viruses that could also be applicable to SARS-CoV-2.

Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2) Science 16 March 2020

https://science.sciencemag.org/content/early/2020/03/13/science.abb3221

Infants born to mother with a new coronavirus (Covid-19). Frontiers in Pediatrics. 16 March 2020

http://dx.doi.org/10.3389/fped.2020.00104

Lloyd-Sherlock P, Ebrahim S, Geffen L et al. Bearing the brunt of covid-19: older people in low and middle income countries. BMJ 16 March 2020

https://doi.org/10.1136/bmj.m1052

Liu C, Zhou Q, Li Y et al. Research & Development on Therapeutic Agents and Vaccines for COVID-19 and Related Human Coronavirus Diseases. ACS Central Science 16 March 2020.

https://doi.org/10.1021/acscentsci.0c00272

Tags: Asia | Flu & Viruses | World Health

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