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SEM of SARS-CoV-2 coronavirus particles (orange) on an apoptotic cell (blue) from a US patient sample. SARS-CoV-2.

A scanning electron microscope image of SARS-CoV-2 coronavirus particles (orange) on a cell (blue).Credit: NIAID/NIH/SPL

Five pressing questions about COVID-19

To mark six months since the world first learnt about COVID-19, Nature runs through some of the key questions that researchers still don’t have answers to. The pandemic has catalysed a research revolution, as scientists, doctors and other scholars have worked at breakneck speed to understand the disease and the virus that causes it: SARS-CoV-2. But for every insight into COVID-19, more questions emerge and others linger.

Nature | 10 min read

Lessons from ‘war-game’ simulations

Biosecurity experts use military-style exercises to plan for biological threats. In this week’s COVID-19 podcast, the Nature news team discusses how these simulations work, what recommendations have come out of them and whether any of these warnings have been heeded.

Nature Coronapod | 33 min listen

Subscribe to the Nature Podcast on iTunes, Google Podcasts or Spotify.

COVID-19 coronavirus update

Most people never show classic symptoms

Less than one-third of people infected with SARS-CoV-2 fall ill with respiratory symptoms or fever, suggests a survey of the hard-hit region of Lombardy, Italy, where 16,000 people have died. Researchers studied 5,484 people who had close contact with an infected person — roughly half got infected, but only 31% developed classic symptoms, such as a cough. As a person’s age increased, so did their odds of experiencing symptoms.

Reference: arXiv preprint (not yet peer reviewed)

Detailed map of a viral protein’s Achilles heel

Scientists have created and described more than 3,800 variations of the protein that the new coronavirus uses to latch on to its targets — a feat that reveals which parts of the protein are crucial for binding to human cells.

Reference: bioRxiv preprint (not yet peer reviewed)

Test frequency matters more than test sensitivity

In outbreak-prone places, authorities should frequently test large numbers of people for the new coronavirus — even if that means using a relatively insensitive test. Researchers modelled the effect of widespread testing on viral spread in a large group of people. Weekly surveillance testing, paired with isolation of infected people, would limit an outbreak even if the testing method was less sensitive than the gold-standard type of test, quantitative polymerase chain reaction (qPCR). By contrast, surveillance testing done every 14 days would allow the total number of infections to climb almost as high as if there were no testing at all.

Reference: medRxiv preprint (not yet peer reviewed)

Get more of Nature’s continuously updated selection of the must-read papers and preprints on COVID-19.

Features & opinion

Nerve agents: from discovery to deterrence

Even with an international convention banning them, the threat of chemical weapons being used outside conventional warfare is ever-present. A history of nerve agents by defence and security expert Dan Kaszeta is weak on some of the complexities of recent politics, writes reviewer Leiv Sydnes, who chaired the international task group that assessed the impact of scientific advances on the Chemical Weapons Convention in 2007 and 2012. But it makes clear a sobering point: it is all too easy for those who seek to do harm to make nerve agents in small quantities.

Nature | 5 min read

COVID-19’s unequal toll in the United States

Data made available after The New York Times sued the US Centers for Disease Control and Prevention show that Black and Latino people have been three times as likely to become infected as have white people. Information from 640,000 cases reveal how factors other than underlying health problems — such as access to health care, job security and the ability to work remotely — affect who gets COVID-19. “Some people have kind of waved away the disparities by saying, ‘Oh, that’s just underlying health conditions,’” says epidemiologist Jennifer Nuzzo. “That’s much harder to do with the case data.”

The New York Times | 13 min read

Australia’s mysterious flesh-eating disease

On the Mornington Peninsula south of Melbourne, “everyone, regardless of their social standing, seemed to know someone” who had had a brush with the mysterious disease Buruli. The flesh-eating bacterium that causes it seems to have no single mode of transmission. Microbiologists’ halting efforts to track down what is spreading the disease reveal the ways in which politics and inequality hinder public-health science.

The Atlantic | 17 min read

Quote of the day

“I can take little satisfaction from this victory for investigative science journalism while I know that the test is still on sale.”

After winning a decade-long legal battle over the story, science journalist Peter Aldhous writes about how a paternity test based on faulty science has upended the lives of an untold number of people. (Buzzfeed News | 17 min read)