IN THIS ISSUE
Paxlovid without a positive test
Yes, home tests are as underreported as we thought
Liquid biopsy provides actionable results in colorectal cancer
Decreasing biosurveillance while zoonosis risk remains
The ants go marching - and sniffing
New and Noteworthy
PHE End Is in Sight
It’s official: The federal COVID-19 Public Health Emergency (PHE) will expire on May 11. That means that health systems (not to mention the government) now have 99 days left to figure out how to return to a non-pandemic footing.
Of note: The end of the PHE will not mean the automatic end of all those EUAs for diagnostics (and other medical devices). According to the FDA, those fall under a different piece of legislation than the PHE itself. (For the policy wonks: It’s section 564 of the Federal Food, Drug, and Cosmetic (FD&C) Act for EUAs, section 319 of the Public Health Service (PHS) Act for the PHE.) For now, that means the EUAs are still valid until the HHS secretary says they aren’t - and the FDA may continue to issue EUAs, as well.
That being said, back in December 2021 the agency published two draft transition plans specifying what will happen when the decision to end the EUAs does finally come down. If those plans are approved (and it looks like they will be soon), medical device companies will have 180 days to make the transition.
The other big question mark for test manufacturers is what will happen to reimbursement for COVID tests - whether they be lab-based, point-of-care, or OTC / at-home tests. More information on that topic is expected in the next few weeks.
Patient feeling poorly, but not positive? No problem. Prescribe Paxlovid.
The FDA announced today that the EUAs for the antivirals Paxlovid and Lagevrio have been changed: If a patient has had recent exposure and symptoms consistent with COVID, health care providers may prescribe these drugs even if the patient hasn’t tested positive. Commentary: This change essentially acknowledges that OTC tests can return false negatives (especially single tests), and that PCR lab tests often take too long to return results. While ultimately the update makes sense - some patients simply never do test positive - we worry that it may erode confidence in tests.
Study brings it home: Home tests are vastly under-reported
Home testing has always had both huge positives and significant challenges. The largest public health-related challenge is the lack of data on test results. This study by the COVID Citizen Science group, with more than 100,000 participants, compares home testing against physician / lab testing from March to August 2022. The results showed that for the first four months, home-test positivity was similar to positivity for lab tests - but that changed in July and August. Since that time, the positivity rate for home tests has been lower than that for lab tests, as home tests have been more and more frequently used. By end of the study, the authors estimate that 80% of tests done were being conducted at home.
When liquid biopsy gives you both bad and good news
As we continue to keep an eye on advancements in liquid biopsy, a recent paper in Nature Medicine piqued our interest. The study looked at circulating tumor DNA (ctDNA) analysis in postsurgical Stage II - IV colorectal cancer patients (more than 30% of whom relapse despite standard treatment).
Turns out that ctDNA analysis can give docs an early heads-up that bad news may be coming: Patients who have circulating ctDNA four weeks post-surgery are 10X more likely to have recurrent disease, and circulating ctDNA was the most significant prognostic indicator for recurrence in folks with Stage II or III cancer. But in addition, that result helps docs know what to do if and when the bad news does arrive: Patients with circulating ctDNA were 6.6X more likely to respond to chemotherapy.
Food for Thought
Complacency: Up. Bio-Surveillance: Down. Zoonosis Risk: Concerning.
Commentary: The US was slow to begin performing the variant sequencing necessary for ongoing COVID variant vigilance. After a rapid late-2021 acceleration (ad-hoc, limited, and arbitrary rather than systematic), we have again dropped below the level required to spot and characterize novel variants.
This needs to change. It is foolhardy to take our eyes off the viral-disease ball - whether the virus in question be COVID, influenza, or other high-mortality pathogens. Bio-surveillance is an essential and inexpensive measure to protect the public, but rather than continuing to strengthen our systems, we are systematically dismantling them.
In case we forget the growing risk of animal diseases to human health, a recent paper in Nature ISME evaluated the risk of cross-infection and found it to be worryingly high across a wide range of animals. We have been fortunate thus far that none of the post-B.1 Omicron variants have increased in virulence, but we cannot rely on that to be the case in perpetuity.
EUA Update
The FDA issued no new EUAs, 10 amendments to existing EUAs, and 4 new safety communications in January.
New EUAs (0):
Amendments to Existing EUA’s (10):
COVID Antigen: 9
Respiratory multiplex (Flu + COVID): 1
Safety Communications (4):
Warning Letters (3): Purecraft LLC | Medical Mikes, Inc. | PharmaCanna
Revocations (1): ChromaCode Inc (requested by manufacturer)
Quick Hits
Ants can be trained to detect the smell of cancer in urine, according to a recent study published in the Proceedings of the Royal Society B (Biological Sciences). Yes - ants! And they’re quick studies, too - it only took three rounds of conditioning for them to learn the distinction.