16 July — Antiviral antibodies peter out within weeks after infection

Key antibodies that neutralize the effects of the new coronavirus fall to low levels within months of SARS-CoV-2 infection, according to the most comprehensive study yet.

Neutralizing antibodies can block a pathogen from infecting cells. But such antibody responses against coronaviruses often wane after just a few weeks.

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Katie Doores at King’s College London and her colleagues monitored the concentration of neutralizing antibodies against SARS-CoV-2 in 65 infected people for up to 94 days (J. Seow et al. Preprint at medRxiv http://doi.org/d3s2; 2020). In a preprint that has not yet been peer reviewed, the team reports that at the peak of antibody production, people with severe COVID-19 symptoms had higher levels of antibodies than had people with mild disease.

However, in most people, antibody levels began to fall about a month after symptoms appeared, sometimes to nearly undetectable levels — raising questions about the durability of vaccines designed to promote the production of neutralizing antibodies.

15 July — Positive trial results raise hopes for a top vaccine candidate

A leading COVID-19 vaccine candidate generates an immune response against the virus and causes few side effects, according to preliminary data from a phase I safety study with 45 participants.

The vaccine is being co-developed by Moderna in Cambridge, Massachusetts, and the US National Institute of Allergy and Infectious Diseases. It consists of RNA instructions that prompt human cells to make the virus’s spike protein, generating an immune response.

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Lisa Jackson at Kaiser Permanente Washington Health Research Institute in Seattle and her colleagues gave participants two injections, administered four weeks apart, of one of three different doses of the vaccine (L. A. Jackson et al. N. Engl. J. Med. http://doi.org/d3tt; 2020). Most side effects were mild, although three participants who got the highest dose experienced worse complications, such as a high fever.

After the injections, all participants produced immune proteins called antibodies capable of recognizing the SARS-CoV-2 virus, as well as ‘neutralizing antibodies’ that can block infection. A 30,000-participant phase III trial to test whether the vaccine can prevent COVID-19 is set to begin in late July.

15 July — Severe COVID-19 has a telltale immune profile

Scientists have identified an immune-system signature in people with serious COVID-19 — a finding that could inform the development of treatments for the disease.

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Benjamin Terrier at the University of Paris and his colleagues analysed blood samples from 50 people infected with SARS-CoV-2 (J. Hadjadj et al. Science http://doi.org/gg4vjx; 2020). Compared to the individuals with mild or moderate symptoms, those with severe disease produced fewer antiviral proteins called interferons and more inflammatory molecules. The researchers also found that blood levels of a specific interferon decreased just before participants had to be taken to intensive-care units.

The results suggest that reduction of interferon levels in the blood is a hallmark of severe COVID-19. Treatments that counter inflammation and increase levels of interferons could help people with the disease, the researchers say.