Your Community and COVID-19: How to Make Sense of the Numbers Where You Live

Your Community and COVID-19: How to Make Sense of the Numbers Where You Live

A map of cumulative known cases of COVID-19 in the U.S., as of June 12th, 2020.

(Screenshot of Johns Hopkins' COVID-19 tracking dashboard at https://rb.gy/qtjbay)



Have you felt a bit like an armchair epidemiologist lately? Maybe you've been poring over coronavirus statistics on your county health department's website or on the pages of your local newspaper.

If the percentage of positive tests steadily stays under 8 percent, that's generally a good sign.

You're likely to find numbers and charts but little guidance about how to interpret them, let alone use them to make day-to-day decisions about pandemic safety precautions.

Enter the gurus. We asked several experts to provide guidance for laypeople about how to navigate the numbers. Here's a look at several common COVID-19 statistics along with tips about how to understand them.

Case Counts: Consider the Context

The number of confirmed COVID-19 cases in American counties is widely available. Local and state health departments should provide them online, or you can easily look them up at The New York Times' coronavirus database. However, you need to be cautious about interpreting them.

"Case counts are the obvious numbers to look at. But they're probably the hardest thing to sort out," said Dr. Jeff Martin, an epidemiologist at the University of California at San Francisco.

That's because case counts by themselves aren't a good window into how the coronavirus is affecting your community since they rely on testing. And testing itself varies widely from day to day and community to community.

"The more testing that's done, the more infections you'll pick up," explained Dr. F. Perry Wilson, a physician at Yale University. The numbers can also be thrown off when tests are limited to certain groups of people.

"If the tests are being mostly given to people with a high probability of having been infected -- for example, they have had symptoms or work in a high-risk setting -- then we expect lots of the tests to be positive. But that doesn't tell us what proportion of the general public is likely to have been infected," said Eleanor Murray, an epidemiologist at Boston University.

These Stats Are More Meaningful

According to Dr. Wilson, it's more useful to keep two other statistics in mind: the number of COVID tests that are being performed in your community and the percentage that turn up positive, showing that people have the disease. (These numbers may or may not be available locally. Check the websites of your community's health department and local news media outlets.)

If the number of people being tested is going up, but the percentage of positive tests is going down, Dr. Wilson said, that's a good sign. But if both numbers are going up – the number of people tested and the percentage of positive results – then "that's a sign that there are more infections burning in the community."

It's especially worrisome if the percentage of positive cases is growing compared to previous days or weeks, he said. According to him, that's a warning of a "high-risk situation."

Dr. George Rutherford, an epidemiologist at University of California at San Francisco, offered this tip: If the percentage of positive tests steadily stays under 8 percent, that's generally a good sign.

There's one more caveat about case counts. It takes an average of a week for someone to be infected with COVID-19, develop symptoms, and get tested, Dr. Rutherford said. It can take an additional several days for those test results to be reported to the county health department. This means that case numbers don't represent infections happening right now, but instead are a picture of the state of the pandemic more than a week ago.

Hospitalizations: Focus on Current Statistics

You should be able to find numbers about how many people in your community are currently hospitalized – or have been hospitalized – with diagnoses of COVID-19. But experts say these numbers aren't especially revealing unless you're able to see the number of new hospitalizations over time and track whether they're rising or falling. This number often isn't publicly available, however.

If new hospitalizations are increasing, "you may want to react by being more careful yourself."

And there's an important caveat: "The problem with hospitalizations is that they do lag," UC San Francisco's Dr. Martin said, since it takes time for someone to become ill enough to need to be hospitalized. "They tell you how much virus was being transmitted in your community 2 or 2.5 weeks ago."

Also, he said, people should be cautious about comparing new hospitalization rates between communities unless they're adjusted to account for the number of more-vulnerable older people.

Still, if new hospitalizations are increasing, he said, "you may want to react by being more careful yourself."

Deaths: They're an Even More Delayed Headline

Cable news networks obsessively track the number of coronavirus deaths nationwide, and death counts for every county in the country are available online. Local health departments and media websites may provide charts tracking the growth in deaths over time in your community.

But while death rates offer insight into the disease's horrific toll, they're not useful as an instant snapshot of the pandemic in your community because severely ill patients are typically sick for weeks. Instead, think of them as a delayed headline.

"These numbers don't tell you what's happening today. They tell you how much virus was being transmitted 3-4 weeks ago," Dr. Martin said.

'Reproduction Value': It May Be Revealing

You're not likely to find an available "reproduction value" for your community, but it is available for your state and may be useful.

A reproduction value, also known as R0 or R-naught, "tells us how many people on average we expect will be infected from a single case if we don't take any measures to intervene and if no one has been infected before," said Boston University's Murray.

As The New York Times explained, "R0 is messier than it might look. It is built on hard science, forensic investigation, complex mathematical models — and often a good deal of guesswork. It can vary radically from place to place and day to day, pushed up or down by local conditions and human behavior."

It may be impossible to find the R0 for your community. However, a website created by data specialists is providing updated estimates of a related number -- effective reproduction number, or Rt – for each state. (The R0 refers to how infectious the disease is in general and if precautions aren't taken. The Rt measures its infectiousness at a specific time – the "t" in Rt.) The site is at rt.live.

"The main thing to look at is whether the number is bigger than 1, meaning the outbreak is currently growing in your area, or smaller than 1, meaning the outbreak is currently decreasing in your area," Murray said. "It's also important to remember that this number depends on the prevention measures your community is taking. If the Rt is estimated to be 0.9 in your area and you are currently under lockdown, then to keep it below 1 you may need to remain under lockdown. Relaxing the lockdown could mean that Rt increases above 1 again."

"Whether they're on the upswing or downswing, no state is safe enough to ignore the precautions about mask wearing and social distancing."

Keep in mind that you can still become infected even if an outbreak in your community appears to be slowing. Low risk doesn't mean no risk.

Putting It All Together: Why the Numbers Matter

So you've reviewed COVID-19 statistics in your community. Now what?

Dr. Wilson suggests using the data to remind yourself that the coronavirus pandemic "is still out there. You need to take it seriously and continue precautions," he said. "Whether they're on the upswing or downswing, no state is safe enough to ignore the precautions about mask wearing and social distancing. 'My state is doing well, no one I know is sick, is it time to have a dinner party?' No."

He also recommends that laypeople avoid tracking COVID-19 statistics every day. "Check in once a week or twice a month to see how things are going," he suggested. "Don't stress too much. Just let it remind you to put that mask on before you get out of your car [and are around others]."

Randy Dotinga
Randy Dotinga is former president of the American Society of Journalists and Authors, a non-profit association of freelance writers and non-fiction authors. He has been a freelance writer since 1999 and specializes in health/medicine, politics, books, and the odd and unusual. You can follow him at @rdotinga.
Breakthrough drones deliver breast milk in rural Uruguay

A drone hovers over Tacuarembó hospital in Uruguay, carrying its precious cargo: breast milk intended for children in remote parts of the country.

Sebastián Macías - Cielum

Until three months ago, nurse Leopoldina Castelli used to send bottles of breast milk to nourish babies in the remote areas of Tacuarembó, in northern Uruguay, by way of ambulances or military trucks. That is, if the vehicles were available and the roads were passable, which wasn’t always the case. Now, five days per week, she stands by a runway at the hospital, located in Tacuarembó’s capital, watching a drone take off and disappear from view, carrying the milk to clinics that serve the babies’ families.

The drones can fly as far as 62 miles. Long distances and rough roads are no obstacles. The babies, whose mothers struggle to produce sufficient milk and cannot afford formula, now receive ample supplies for healthy growth. “Today we provided nourishment to a significantly larger number of children, and this is something that deeply moves me,” Castelli says.

About two decades ago, the Tacuarembó hospital established its own milk bank, supported by donations from mothers across Tacuarembó. Over the years, the bank has provided milk to infants immediately after birth. It's helped drive a “significant and sustained” decrease in infant mortality, says the hospital director, Ciro Ferreira.

Keep Reading Keep Reading
Maria De Los Ángeles Orfila
María de los Ángeles Orfila is a science journalist based in Montevideo, Uruguay, with more than 18 years of experience in journalism. Her long-form writing has been featured in El País, and El Observador, two of the most influential newspapers in her country. She is currently participating in the Sharon Dunwoody Mentoring Program 2023 offered by The Open Notebook.
After spaceflight record, NASA looks to protect astronauts on even longer trips

NASA astronaut Frank Rubio floats by the International Space Station’s “window to the world.” Yesterday, he returned from the longest single spaceflight by a U.S. astronaut on record - over one year. Exploring deep space will require even longer missions.

NASA

At T-minus six seconds, the main engines of the Atlantis Space Shuttle ignited, rattling its capsule “like a skyscraper in an earthquake,” according to astronaut Tom Jones, describing the 1988 launch. As the rocket lifted off and accelerated to three times the force of Earth's gravity, “It felt as if two of my friends were standing on my chest and wouldn’t get off.” But when Atlantis reached orbit, the main engines cut off, and the astronauts were suddenly weightless.

Since 1961, NASA has sent hundreds of astronauts into space while working to making their voyages safer and smoother. Yet, challenges remain. Weightlessness may look amusing when watched from Earth, but it has myriad effects on cognition, movement and other functions. When missions to space stretch to six months or longer, microgravity can impact astronauts’ health and performance, making it more difficult to operate their spacecraft.

Keep Reading Keep Reading
Gail Dutton
Gail Dutton has covered the biopharmaceutical industry as a journalist for the past three decades. She focuses on the intersection of business and science, and has written extensively for GEN – Genetic Engineering & Biotechnology News, Life Science Leader, The Scientist and BioSpace. Her articles also have appeared in Popular Science, Forbes, Entrepreneur and other publications.