Coronavirus research updates: For fast and low-cost COVID-19 testing, just spit

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Nature wades through the literature on the new coronavirus — and summarizes key papers as they appear.

A health worker in Rybnik, Poland, carries a sample from a coal miner for SARS-CoV-2 testing. Credit: Omar Marques/Getty

7 August — For fast and low-cost COVID-19 testing, just spit

A quick, cheap and painless test that detects SARS-CoV-2 RNA in spit could be used for mass testing.

Chantal Vogels at Yale School of Medicine in New Haven, Connecticut, and colleagues developed a simple saliva test — called SalivaDirect — to address the growing demand for extensive testing as lockdowns lift (C. B. F. Vogels et al. Preprint at medRxiv http://doi.org/d5s3; 2020).

Compared with the gold-standard nose and throat swab, the saliva test is less invasive, does not need to be conducted by a trained professional and avoids the use of scarce chemicals that are needed to store and extract viral RNA. Invalidation experiments, SalivaDirect detected 32 out of 34 samples that tested positive in nose and throat swabs, and 30 out of 33 negative samples.

The researchers estimate a cost-per-spit of US$1.29–$4.37 and have requested that the United States Food and Drug Administration authorize the test for emergency use.

A cell infected with particles of SARS-CoV-2.Credit: Cynthia S. Goldsmith and Azaibi Tamin/CDC/SPL

6 August — Immune reaction to some common colds might provide protection

Some immune cells that recognize coronaviruses that cause the common cold also respond to SARS-CoV-2, the coronavirus responsible for the COVID-19 pandemic.

Previous studies have found that some people who have never been exposed to SARS-CoV-2 nevertheless have immune cells called memory T cells that can recognize the virus. Daniela Weiskopf and Alessandro Sette at the La Jolla Institute for Immunology in California analysed such T cells and found that they recognize particular sequences of several SARS-CoV-2 proteins (J. Mateus et alScience http://doi.org/d5v5; 2020).

The team then identified similar sequences in common-cold coronaviruses and showed these sequences could activate some T cells that also respond to SARS-CoV-2. The findings add weight to the hypothesis that existing immunity to cold coronaviruses could contribute to differences in COVID-19 severity, but further studies are required to support that conclusion.

5 August — Antibody blend protects monkeys and hamsters from viral symptoms

A mixture of two human antibodies against the new coronavirus shows promise in animal tests for preventing and treating COVID-19.

Neutralizing antibodies are immune molecules that can attach to viruses and disable them. Christos Kyratsous at Regeneron Pharmaceuticals in Tarrytown, New York, and his colleagues made a cocktail of two neutralizing antibodies that bind SARS-CoV-2. They gave the cocktail to rhesus macaques (Macaca mulatta), which become mildly ill when infected.

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