New Scientist: Covid-19 is becoming less deadly in Europe but we don't know why

 In England, the proportion of people infected by the coronavirus who later died was certainly lower in early August than it was in late June. Over the period, this infection fatality rate (IFR) dropped by between 55 and 80 per cent, depending on which data set was used, found Jason Oke at the University of Oxford and his colleagues. [...]

Nonetheless, why this is happening isn’t so clear. According to data for England, a larger proportion of younger people are being infected than was happening around the first peak of cases in April, with cases rates for 10-16 August the highest among 15-44 year olds. [...]

The jury is out on whether one variant of the coronavirus, known as D614G, explains why covid-19 is becoming less deadly. Paul Tambyah at the National University of Singapore told Reuters that the rise of the D614G mutation had coincided with drops in death rates in some countries, suggesting that it might be “more infectious but less deadly”.

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New Scientist: We may finally know what causes Alzheimer’s – and how to stop it

However evidence has been growing that the function of amyloid proteins may be as a defence against bacteria, leading to a spate of recent studies looking at bacteria in Alzheimer’s, particularly those that cause gum disease, which is known to be a major risk factor for the condition.

Bacteria involved in gum disease and other illnesses have been found after death in the brains of people who had Alzheimer’s, but until now, it hasn’t been clear whether these bacteria caused the disease or simply got in via brain damage caused by the condition.  [...]

In the new study, Cortexyme have found the toxic enzymes that P. gingivalis uses to feed on human tissue – called gingivains – in 96 per cent of the 54 Alzheimer’s brain samples they studied. They also found the bacteria themselves in all three Alzheimer’s brains whose DNA they examined.[...]

Some brain samples from people without Alzheimer’s also had P. gingivalis and protein accumulations, but at lower levels. We already know that amyloid and tau can accumulate in the brain for 10 to 20 years before Alzheimer’s symptoms begin. This, says Lynch, shows P. gingivalis is a cause of Alzheimer’s, not a result.

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