Asymptomatic coronavirus sufferers appear to lose detectable antibodies sooner than people who have exhibited Covid-19 symptoms, according to one of the biggest studies of its kind in Britain published on Tuesday.
The findings by Imperial College London and market research firm Ipsos Mori also suggest the loss of antibodies was slower in 18–24 year-olds compared to those aged 75 and over. Overall, samples from hundreds of thousands of people across England between mid-June and late September showed the prevalence of virus antibodies fell by more than a quarter.
The research, commissioned by the British government and published Tuesday by Imperial, indicates people’s immune response to Covid-19 reduces over time following infection. James Bethell, a junior health minister, called it “a critical piece of research, helping us to understand the nature of Covid-19 antibodies over time”.
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But scientists involved cautioned that a great deal remains unknown about people’s long-term antibody response to the virus. “It remains unclear what level of immunity antibodies provide, or for how long this immunity lasts,” said Paul Elliott, of Imperial’s School of Public Health.
The study involved 365,000 randomly-selected adults administering at home three rounds of finger prick tests for coronavirus antibodies between June 20 and September 28. The results showed the number of people with antibodies fell by 26.5 percent over the approximate three-month period.
Asymptomatic virus sufferers lose antibodies sooner https://t.co/3xNX29vmH6
— Galileo B. Luzano (@LuzanoB) October 27, 2020
Scaled up to a nationwide level, it meant the proportion of the English population with antibodies dropped from 6.0 percent to 4.4 percent, according to the study. The decline coincided with the prevalence of the virus falling dramatically across England — and the rest of Britain — following a months-long national shutdown which was eased over the summer.
However, the research found the number of health care workers testing positive for antibodies did not change over time, potentially reflecting repeated, or higher initial, exposure to the virus. “This very large study has shown that the proportion of people with detectable antibodies is falling over time,” said Helen Ward, one of the lead authors.
Read more: US: COVID-19 testing for asymptomatic people not neccessary after exposure
“We don’t yet know whether this will leave these people at risk of reinfection with the virus that causes Covid-19, but it is essential that everyone continues to follow guidance to reduce the risk to themselves and others.”
Air pollution linked to 15 percent of coronavirus deaths: study
Long-term exposure to air pollution may be linked to 15 percent of Covid-19 deaths globally, according to research published Tuesday that highlights the health risks posed by greenhouse gas emissions.
Previous research has showed how air pollution from exhaust fumes and factories takes two years off the life expectancy of every man, woman and child on Earth.
Now experts in Germany and Cyprus say they have estimated the proportion of deaths from coronavirus that can be blamed of the exacerbating effects of air pollution.
Their study, published in the journal Cardiovascular Research, drew on health and disease data from the US and China relating to air pollution, Covid-19 and SARS — a serious lung disease similar to Covid.
They combined this with satellite data of global exposure to particulate matter — microscopic particles — as well as ground-based pollution monitoring networks, to calculate to what extent air pollution can be blamed for Covid-19 deaths.
In East Asia, which has some of the highest levels of harmful pollution on the planet, the authors found that 27 percent of Covid-19 deaths could be attributed to the health effects of poor air quality.
In Europe the proportion was 19 percent, compared with 17 percent in North America.
“If both long-term exposure to air pollution and infection with the Covid-19 virus come together then we have an adverse effect on health, particularly with respect to the heart and blood vessels,” said paper co-author Thomas Munzel.
He said that air pollution made known Covid-19 risk factors such as lung and heart problems more likely.
Specifically, the team noted that particulate matter appeared to increase the activity of a receptor on lung cell surfaces, ACE-2, which is known to be involved in the way Covid-19 infects patients.
“So we have a double hit: air pollution damages the lungs and increases the activity of ACE-2, which in turn leads to enhanced uptake of the virus,” said Munzel, a professor at the University Medical Center of the Johannes Gutenberg University, Mainz.
 ‘Remedy is reduce emissions’Â
The authors stressed that attributing Covid-19 deaths to air pollution did not mean that pollution itself was killing people with Covid — though they didn’t rule out such a cause-effect linkage.
Jos Lelieveld, of the Max Planck Institute for Chemistry, told AFP that the research suggested “the pollution particles are a co-factor in aggravating the disease”.
He said their estimates suggested that more than 6,100 Covid deaths in Britain could be attributed to air pollution. In the US that figure is around 40,000.
The authors said that without a fundamental change in how cities power themselves, including a transition to clean and renewable energy sources, air pollution would continue to kill huge numbers of people even after the pandemic recedes.
“The pandemic ends with the vaccination of the population or with herd immunity through extensive infection of the population,” they wrote.
“However, there are no vaccines against poor air quality and climate change. The remedy is to mitigate emissions.”
AFP with additional input by GVS News Desk