Coronavirus Watch: 'This change in policy will kill'

The Centers for Disease Control and Prevention is now advising that people without symptoms "do not necessarily need a test" – even if they've been exposed to COVID-19.

Infectious disease experts are not only confused, but also troubled, by the policy change.

"Our work on the ‘silent’ spread underscored the importance of testing people who have been exposed to COVID-19 regardless of symptoms," tweeted Alison Galvani, director for the Center for Infectious Disease Modeling and Analysis at Yale School of Medicine. "This change in policy will kill."

It's Wednesday, and this is the Coronavirus Watch from the Paste BN Network. Here is the most significant news of the day, as of 12:30 p.m. ET:

• Biotech company Moderna announced that a small study of its potential vaccine shows it's as safe and apparently effective in older adults as in younger ones.
• Oahu, Hawaii's most populous island, is returning to stay-at-home orders in its fight against COVID-19.
• Florida's medical examiners – facing a massive statewide backlog – are no longer required to certify COVID-19 deaths. It means that deaths will be more quickly counted but will likely create tracking inconsistencies. 
• Two patients in Europe have been reinfected with COVID-19, further emphasizing the necessity of a vaccine as opposed to relying on herd immunity. Both cases — one in the Netherlands, the other in Belgium — were proven to be different strains of the virus, Reuters reported.
• After the Food and Drug Administration offered shaky data to justify its approval of blood plasma to treat COVID-19, some scientists are worried the agency could bow to pressure to approve a coronavirus vaccine before it's fully tested.
• Good news: The nation's county with the highest number of COVID-19 infections is seeing a decline in confirmed cases. The Los Angeles County Public Health Department confirmed 989 new infections Tuesday, marking the first time it has reported less than 1,000 daily cases since the beginning of June.

Today's numbers: The U.S. has more than 5.7 million confirmed infections and 178,000 deaths. Worldwide, there have been more than 820,000 deaths and 23.9 million cases, according to John Hopkins University data. See the numbers in your area here, and check out where cases are rising here.

What do you want to know about the coronavirus? Submit your questions through this form. William from Willows, California, asks: With the recent news about false positive testing, do we know if we have more false positives or false negatives?

When it comes to rapid tests, false negatives are more likely than false positives and are of greater concern. While positive results from these tests are usually highly accurate, negative results may need to be confirmed with a molecular test, according to the FDA.

There are two kinds of diagnostic tests for COVID-19 to determine if you're actively infected: molecular tests, such as PCR tests, that detect the virus’s genetic material, and antigen tests that detect specific proteins on the surface of the virus.

When we say "rapid tests," we're referring to antigen tests. Testing materials for antigen tests are cheaper and more plentiful, and the tests are fast, delivering results in 15 minutes. But researchers are raising concerns about inaccurate results from rapid tests.

Molecular tests, meanwhile, are "highly accurate" and find even low levels of the virus, so they have been the diagnostic test for public health and clinical labs since the beginning of the pandemic.

As always, thank you for subscribing! We appreciate you trusting the Paste BN Network with this important information. Know someone who could benefit from these daily updates? Forward them this email so they can sign up here.

– Grace Hauck, Paste BN breaking news reporter, @grace_hauck