Sign up for our daily briefing

Make your busy days simpler with the Axios AM and PM newsletters. Catch up on what's new and why it matters in just 5 minutes.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on the day's biggest business stories

Subscribe to the Axios Closer newsletter for insights into the day’s business news and trends and why they matter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sign up for Axios Pro Rata

Dive into the world of dealmakers across VC, PE and M&A with Axios Pro Rata. Delivered daily to your inbox by Dan Primack and Kia Kokalitcheva.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sports news worthy of your time

Binge on the stats and stories that drive the sports world with the Axios Sports newsletter. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Tech news worthy of your time

Get our smart take on technology from the Valley and D.C. with Axios Login. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Get the inside stories

Get an insider's guide to the new White House with Axios Sneak Peek. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Denver news?

Get a daily digest of the most important stories affecting your hometown with Axios Denver

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Des Moines news?

Get a daily digest of the most important stories affecting your hometown with the Axios Des Moines newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Twin Cities news?

Get a daily digest of the most important stories affecting your hometown with Axios Twin Cities

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Tampa Bay news?

Get a daily digest of the most important stories affecting your hometown with the Axios Tampa Bay newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Charlotte news?

Get a daily digest of the most important stories affecting your hometown with Axios Charlotte

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Nashville news?

Get a daily digest of the most important stories affecting your hometown with the Axios Nashville newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Columbus news?

Get a daily digest of the most important stories affecting your hometown with the Axios Columbus newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Dallas news?

Get a daily digest of the most important stories affecting your hometown with the Axios Dallas newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Austin news?

Get a daily digest of the most important stories affecting your hometown with the Axios Austin newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Atlanta news?

Get a daily digest of the most important stories affecting your hometown with the Axios Atlanta newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Philadelphia news?

Get a daily digest of the most important stories affecting your hometown with the Axios Philadelphia newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Chicago news?

Get a daily digest of the most important stories affecting your hometown with the Axios Chicago newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sign up for Axios NW Arkansas

Stay up-to-date on the most important and interesting stories affecting NW Arkansas, authored by local reporters

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top DC news?

Get a daily digest of the most important stories affecting your hometown with the Axios DC newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Photo: Faris Hadziq/SOPA Images/LightRocket via Getty Images

Increasing the number of coronavirus tests performed relative to a country's caseload was the strategy most associated with reducing the transmission rate of the virus, according to a new study published in Health Affairs.

Yes, but: The U.S. overall had a low testing intensity between March and June, which means that "testing mostly diagnosed and isolated the most symptomatic cases, which has limited impact on transmission."

  • Even though we're now doing more than a million tests a day, it's not enough to keep up with our ever-rising caseloads.

Details: A tenfold increase in the ratio of tests to new cases reduced average transmission by 9%, the study found.

Between the lines: "Around half or more of COVID-19 transmission is caused by people who are asymptomatic or who have only minor symptoms, so only increases in PCR testing make it possible to increase detection and isolation of infectious cases, and then to increase the numbers of their potentially infectious contacts who are isolated," the authors write.

  • "This remains the only known approach that blocks person-to-person transmission sufficiently to stop the epidemic."

Bonus: The study also found that "being a US territory was also significantly associated with a 12.7% ... increase in transmissibility compared to the rest of the world."

Go deeper

Updated 8 hours ago - Politics & Policy

Omicron dashboard

Illustration: Brendan Lynch/Axios

  1. Health: Omicron pushes COVID deaths toward 2,000 per day — The pandemic-proof health care giant.
  2. Vaccines: No evidence that healthy children, teens need boosters, WHO says — Starbucks drops worker vaccine or test requirement after SCOTUS ruling — Kids' COVID vaccination rates are particularly low in rural America.
  3. Politics: Biden concedes U.S. should have done more testing — Arizona says it "will not be intimidated" by Biden on anti-mask school policies.
  4. World: American Airlines flight to London forced to turn around over mask dispute — WHO: COVID health emergency could end this year — Greece imposes vaccine mandate for people 60 and older.
  5. Variant tracker
Jan 30, 2021 - World

Germany to impose travel restrictions to curb spread of coronavirus variants

Border police officers check passports and COVID-19 tests at Frankfurt Airport. Photo: Thomas Lohnes via Getty Images

Germany announced Friday that it was imposing new travel restrictions in an effort to curb the spread of more contagious coronavirus variants.

Details: All non-German residents traveling from countries deemed "areas of variant concern," including the United Kingdom, South Africa, Portugal, Ireland, Brazil, Lesotho and Eswatini, will be banned from entering the country, even if they test negative for the coronavirus.

Jan 29, 2021 - Health

J&J says its one-shot vaccine is 66% effective against moderate to severe COVID

Photo: Thiago Prudêncio/SOPA Images/LightRocket via Getty Images

Johnson & Johnson announced Friday that its single-shot coronavirus vaccine was 66% effective in protecting against moderate to severe COVID-19 disease in Phase 3 trials, which was comprised of nearly 44,000 participants across eight countries.

Between the lines: The vaccine was 72% effective in the U.S., but only 57% effective in South Africa, where a more contagious variant has been spreading. It prevented 85% of severe infections and 100% of hospitalizations and deaths, according to the company.