Since the beginning of the pandemic, Americans have heard about the importance of testing to control infections. Our latest article on COVID-19 testing explains why one particular measure – the positivity rate – is the best way to gauge the spread of the disease.

Also in this week’s science and research news: how loneliness affects the brains of older people, the dangers to water supplies from wildfires and two neuroscientists explain progress on a blood test for Alzheimer’s.

Martin La Monica

Deputy Editor

As cases surge, testing needs to increase as well. AP Photo/David J. Phillip

Test positivity rate: How this one figure explains that the US isn’t doing enough testing yet

Ronald D. Fricker, Jr., Virginia Tech

Test positivity rates measure the success of a testing program. Even though the US performs a huge number of tests, high test positivity rates across the country show that that it still isn't enough.

In healthy older people, loneliness has a pattern of stress response similar to that of people who are under chronic stress. Justin Paget via Getty Images

The loneliness of social isolation can affect your brain and raise dementia risk in older adults

Karra Harrington, Pennsylvania State University; Martin J. Sliwinski, Pennsylvania State University

The social isolation older adults are experiencing as they try to stay safe from the coronavirus pandemic is raising new mental health risks, but people can take steps to protect themselves.

The 2018 Camp Fire north of Sacramento burned everything in its path: cars, power lines, and buildings – and contaminated local drinking water. Justin Sullivan/Getty Images

Wildfires can poison drinking water – here’s how communities can be better prepared

Andrew J. Whelton, Purdue University; Caitlin R. Proctor, Purdue University

Buildings aren't the only things at risk in wildfires. Recent disasters in California have left local water system contaminated with toxic chemicals afterward, slowing return and recovery.

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