Top science stories of the week – from short-lived immunity to experts ‘cautiously optimistic’about vaccine results

  • Promising initial results from Moderna vaccine candidate but further trials vital
  • Mounting evidence that air pollution worsens coronavirus.
  • Study suggests that immunity to COVID-19 is short-lived.

First data from Moderna vaccine trial show it spurs an immune response

Published on Tuesday (13 July) in the New England Journal of Medicine, results show that Moderna’s COVID-19 vaccine led patients to produce antibodies that neutralize the novel coronavirus that causes the disease.

The study, which was run by the National Institutes of Health, showed that 45 volunteers who received the vaccine (two doses 28 days apart) had higher levels of antibodies than those who had recovered from being infected by COVID-19. The peak in antibody production came only after the second shot.

“The hallmark of a vaccine is one that can actually mimic natural infection and induce the kind of response that you would get with natural infection. And it looks like, at least in this limited, small number of individuals, that is exactly what’s happening,” said Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases.

More than 150 efforts are underway worldwide to develop vaccines for COVID-19. Moderna’s vaccine is one of 23 in human trials, and a handful entering phase 3 of clinical trials. The scientific community is cautiously optimistic of the news, which comes as cases of COVID-19 continues surge in the United States and around the world.

The Moderna Phase 3 trial will recruit 30,000 patients and begin on 27 July, with the aim of balancing safety and efficacy. Researchers will be looking to see how large a dose of the vaccine is necessary to make it effective, while also minimising unpleasant and potentially harmful side effects.

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Further evidence that air pollution worsens coronavirus

A new study, which is to be published in the journal Environmental and Resource Economics, adds to existing evidence that air pollution could significantly increase COVID-19 infections, hospital admissions and deaths.

Researchers from the University of Birmingham looked at the relationship between COVID-19 cases and exposure to air pollution in the Netherlands. After analysing data for 355 Dutch municipalities, the team found that a small, single-unit increase in people’s long-term exposure to pollution particles raised infections and admissions by about 10% and deaths by 15%. The study took into account more than 20 other factors, including average population density, age, household size, occupation, obesity, closeness to international borders, smoking, level of education and even after accounting for such factors, a positive correlation between air pollution and COVID-19 was found.

This latest study is unique in that some of the worst air pollution in the Netherlands occurs not in cities but in some rural areas due to intensive livestock farming. While this latest study does not establish a causal link between exposure to air pollution and COVID-19, further studies using individual-level data rather than averages across regions could. Knowing whether increased air pollution does indeed worsen coronavirus would help to better signal where potential future waves of COVID-19 could have the worst impact.

Immunity to COVID-19 could disappear in months

New research from a team at King’s College London found steep drops in patients’ antibody levels three months after infection, adding to the evidence that people could become reinfected in seasonal waves and that vaccines may not protect them for long.

The study, which has been submitted to a journal but has yet to be peer-reviewed, analysed the immune response of more than 90 patients and healthcare workers in London and found that the levels of antibodies required to destroy the virus peaked about three weeks after the onset of symptoms and then declined. Blood tests showed that 60% of people had a “potent” antibody response at the height of their battle with the virus but only 17% of people retained the same potency three months later, with some who had undetectable levels of antibodies.

“People are producing a reasonable antibody response to the virus, but it’s waning over a short period of time and depending on how high your peak is, that determines how long the antibodies are staying around,” said Dr Katie Doores, lead author of the study.

The results have implications for the development of vaccine as any vaccine candidate would need to provide consistent and sustained levels of protective antibodies, which may require the use of annual boosting immunisations, like the seasonal flu vaccine. It also adds to the growing body of evidence that immunity to COVID-19 is short-lived, which could render the concept of natural herd immunity obsolete.

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