A waning antibody defense
In what could be a blow to hopes for a swift end to the pandemic, a large-scale study from the U.K. has found that levels of protective antibodies decline rapidly after a coronavirus infection. Scientists at Imperial College London analyzed the results of finger-prick antibody tests carried out at home by 365,000 randomly selected adults. In the first round of testing, which ended in June, 6 percent of participants had detectable antibodies. But in the latest set of tests, in September, that figure was
4.4 percent—a fall of 26 percent. The decline was greater among people age 75 and over than in younger groups, and sharper among those who experienced no symptoms than in those with full-blown Covid-19. It remains unclear what this means for immunity, because T-cells and other parts of the immune system can also help prevent reinfection. But the researchers say antibodies tend to be a good marker for immunity. “On the balance of evidence,” study coauthor Wendy Barclay tells BBC.com, “it [looks] as if immunity declines away at the same rate as antibodies decline away.”
10 years. That’s the conclusion of a new study of more than 84,000 people who had recovered from a confirmed or suspected infection, reports The Times (U.K.). The participants were given a series of cognitive tests—such as remembering words or joining dots on a puzzle. The patients who’d been sickest, requiring a ventilator or treatment in intensive care, showed the highest drop-off in brain function. Yet even those who had not been hospitalized or suffered breathing problems exhibited some cognitive decline. “The results align with the ‘brain fog’ reported by many people who, even months after recovery, say they are unable to concentrate on work or focus [as they had] before,” says lead author Adam Hampshire, from Imperial College London. But some scientists said the findings should be treated with caution, because the study didn’t look at the cognitive function of participants before they were infected, so the long-term picture isn’t clear.