Coronavirus Research Tracking - 13 November
Mink mutations, nasal sprays, vaccine progress, mental health
In this week’s Research Tracker we highlight papers about new virus mutations appearing in mink, nasal sprays to block transmission, Pfizer’s preliminary vaccine results, the uses and limits of tracking mobility through phone data, and mental health impacts.
The Research Tracker is prepared by Dr Robert Hickson for the Science Media Centre.
Mink and mutations
At the start of the week the Danish Ministry of Environment and Food announced a cull of all the country’s farmed mink. This is to prevent people being infected by new variants of SARS-CoV-2 found in mink.
A working paper from the Statens Serum Institute describes several mutations in the spike protein from viruses in mink. Some of the mutations cause amino acid deletions or other changes in the spike protein and may reduce the effectiveness of vaccines under development.
Some scientists, as reported in Stat News, think the risk may be overestimated. However, in Science other researchers say that such a cautious approach is justifiable while further information is being collected.
Later in the week the cull was halted, at least temporarily. The Danish government acknowledged that it has no legal basis to compel farmers to kill all of their animals. It is planning to introduce legislation to enable it to do so.
A separate paper published in Science confirmed mink to human transmission of SARS-CoV-2 in the Netherlands. The paper notes the high population densities of mink on such farms and the consequent rapid spread between animals. This leads to more cycles of transmission, and so more mutations.
A nasal spray blocks infection in ferrets
Staying with the mustelid family, a small trial, not yet peer reviewed, used ferrets to test an infection inhibitor. The researchers created the inhibitor from a highly conserved repeat unit that lies near the end of the spike protein and formulated it into a spray.
They tested its effectiveness by housing ferrets infected with the virus alongside ferrets who received the inhibitor and others that did not. After three weeks none of the six ferrets given the inhibitor developed infections or antibodies, while the six untreated ferrets became infected.
Could chicken antibodies provide short term protection?
Research is underway to find out whether nasal drops containing chicken IgY antibodies to SARS-CoV-2 can provide short term protection in people. A phase 1 clinical trial, in Australia, is seeing if the drops are safe.
The antibodies were collected from eggs produced by chickens injected with the virus. It is hoped that such antibodies could provide a few hours protection from infection, and so could be taken before a flight or before entering a crowded place. This has not yet been proven, so don’t sniff your chooks. Details about the technique and trial are reported in a Science news item.
Don’t count your vaccine chickens before they hatch
While the preliminary results of the Pfizer/BioNTech phase 3 trial look very promising there is still a way to go.
A 2018 paper in Nature Reviews Drug Discovery described the advantages and disadvantages of mRNA vaccines.
An October article published in The British Medical Journal noted that current vaccine trials aren't designed to determine the effects on transmission and disease severity.
Another October commentary, in Science, called for surveillance studies of people receiving Covid-19 vaccines. This would provide a better understanding of how well vaccines work for different groups.
Derek Lowe’s blog for Science Translational Medicine, and Siouxsie Wiles item for The Spinoff discuss these and other challenges for the Pfizer vaccine.
Research still required on immune benefits of other coronavirus infections
Research published in Science describes several antibodies found in people from before the pandemic that cross-react with the SARS-CoV-2 virus. How well they neutralise the virus is unknown, but the researchers found that these antibodies were more commonly found in children and adolescents, who are generally less susceptible to Covid-19.
They point to other research demonstrating that young people typically have more coronavirus infections than adults, and so a higher proportion of young people may have these antibodies during the pandemic. This may contribute to their lower levels of infection, but it that hasn’t yet been proven.
The paper also speculates that the conserved nature of parts of the coronavirus spike protein may enable development of a universal coronavirus vaccine.
T-cell immunity can last at least 6 months
A study monitoring T cell responses in 100 infected people found that the virus-specific T cells persisted for six months. This implies cellular (T cell) immune reactions, like humoral (antibody) immunity, can be relatively long lasting. Higher levels of T cell response were associated with patients who displayed Covid-19 symptoms. This supports other research that more severe infections are associated with stronger immune reactions. The study has not yet been peer-reviewed.
Rapid tests not yet ready for the home
Last week’s Tracker noted some rapid virus tests under development. An article in Nature Biotechnology notes that while development of more rapid clinical tests is progressing, approval for rapid home use tests are likely to be slower. This is because they can be harder for non-medical people to interpret, so regulators are reluctant to approve them.
The article also notes the need to move on from simply testing for the presence of the virus or antibodies. More accurate antigen tests, which can help identify who is infectious, are needed.
Increased psychiatric diagnoses associated with Covid-19
An increased incidence of psychiatric diagnoses has been found in a study of 62,000 Covid-19 cases in the USA. Nearly 6% of people with Covid-19 had their first psychiatric diagnosis, compared with 2.5-3.4% for those without Covid-19. Anxiety disorders, insomnia, and dementia were the most commonly reported diagnoses.
A psychiatric diagnosis in the previous year was also associated with a higher incidence of COVID-19 diagnosis. The longer term impacts of these mental health challenges are unknown. The research was published in The Lancet Psychiatry.
Eat, pray, buff - places to avoid in a pandemic
Research on mobility patterns during the pandemic studied the movements of 98 million people in ten of the US’s largest metropolitan areas. The results, published in Nature, predict a small number of potential “super-spreader” venues - full-service restaurants, places of worship, and gyms. These were disproportionately associated with infections.
However, the study could only map where people went, not where they became infected. It also didn't include schools and nursing homes.
Mobility isn’t everything
Caution in using mobile data to study transmission is also called for in a paper in The Lancet Infectious Diseases. It notes that mobility alone doesn’t control transmission. Environmental and behavioural factors, not just location, are important determinants of infection.
A good visual explainer of super-spreading was produced by Science.
Covid innovations
In the not-really-research section, a website called Covid Innovations gives examples of how the pandemic has led to various types of business innovation.