P.Resident Biden’s recent Covid-19 case, its rebound, and his lengthy isolation will use PCR testing to more accurately interpret viral load to help people return to work and school safely and early. It provides an opportunity to consider how it can be used to
Biden tested positive for SARS-CoV-2, the virus that causes Covid-19, on July 21 after he started feeling runny nose, dry cough and fatigue the night before. He took the antiviral drug Paxlovid as prescribed for five days. He feels well and a battery of tests showed that his body had cleared the virus on his July 26th. He returned to work on his July 27th, following guidelines set by the Centers for Disease Control and Prevention. But on July 30, the president tested positive again and, according to a note from his personal physician Kevin C. was forced to
That said, the decision was significant enough within the current caveats. Despite his good mood, the president was forced to cancel a trip to advocate legislation to support the domestic semiconductor industry. It was August 7 when he returned to “public engagements and presidential travels.”
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The re-emergence of the SARS-CoV-2 virus after treatment — also known as paxlovid rebound — is increasingly recognized by clinicians. It can occur when viral reservoirs are suppressed by antiviral therapy but not eradicated by it. , suggesting that new strategies such as extending the duration of treatment from 5 to 10 days should be evaluated.
This raises an important question: Do such individuals carry enough virus to infect others?
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Current recommendations for returning to school and work (which the Washington Post and others call confusing) rely on empirical observations. Symptoms, timing and results of Covid testing, rapid antigen testing governments, such as home testing, which is typically federally provided. The imprecision of such guidance leaves uncertainty for both individuals and public health officials as they grasp more actionable data.
This is where “gold standard” testing (PCR-based testing) adds value. PCR tests measure SARS-CoV-2 differently than antigen tests. Not only are they highly accurate, capable of detecting infection before symptoms begin, rapid antigen tests are often negative, but they can also provide quantitative results throughout the course of infection. The downside is that the infectivity cannot be read immediately because the sample taken for PCR testing must be sent to the lab for analysis.
Modeling suggests that this ability of PCR tests to quantify viral load can translate into the risk of transmitting SARS-CoV-2 to others. Consecutive positive PCR results during the course of infection or after paxlovid rebound offer the possibility of objectively and quantitatively interpreting how important a positive result really is. If the viral load is high, individuals should continue to take precautions to prevent infecting others. If it’s low, you can be sure you don’t have enough virus to infect others and you can go back to work (until the virus is completely cleared or 10 days have passed before wearing a mask). To do).
Quantitative details of Biden’s PCR test have not been made public. However, this information could have been used by doctors to determine whether the need for isolation was high or low. It may also imply little or no further risk of wearing a high-quality mask (such as KN95) strictly when in close proximity to others, or especially if there are no symptoms. there is. To the health of him and those around him.
Translating viral laboratory data into clinical decision-making requires greater attention, but various studies are beginning to consider contagiousness and viral load. This is probably the first cluster of Covid-19 infections in Germany (both pre-Omicron) by Ruian Ke and his colleagues who examined viral transmission among NBA players and nine individuals tested consecutively. analyzed most clearly. Their modeling showed that contagion was high early after infection when viral load was below the limit that could be reliably detected by rapid antigen testing, but contagion risk usually persisted for up to 10 days and beyond. Rarely. The risk of infection, especially early after exposure, may be even greater with current variants.
However, such studies are not reflected in Covid management recommendations. This is partly because it provides a set of risk probabilities that are useful to health policy makers but less useful to infected individuals and their clinicians. Nevertheless, the current emphasis on rapid tests that do not yield quantitative information can be complemented (or improved) by the use of quantitative PCR tests.
The Rockefeller University Covid-19 clinical laboratory where I work has implemented an easy-to-use, sensitive, and inexpensive serial PCR saliva testing program to ensure the safety of children, staff, and families in the university’s pre-kindergarten program. helps to maintain. The program will be open during the pandemic.
Asymptomatic individuals who are positive for SARS-CoV-2 by PCR or rapid antigen test can be retested and, if the PCR test is negative on retest, return to school or work in as little as 3-5 days. can return to Those who experience rebound or persistent positive PCR or rapid antigen testing for paxlobid can be triaged according to symptoms and viral load. PCR-positive individuals who are feeling well but have a low viral load and are at low risk of infection (defined by Rockefeller’s current guidance as a viral load of less than approximately 1,000 copies per milliliter of saliva) are encouraged to attend school and work. You can go back. However, you must wear a KN95 mask until a test shows that you have cleared the virus or 10 days have passed.
Rockefeller and other New York City clinical labs, such as the Pandemic Response Lab, are pushing for PCR test results to be submitted within 24 hours. .
Decisions about returning to work are clinical and can now be complemented by rigorous numerical data. If widely implemented, viral load awareness, or risk of contagion, could be communicated to all administrators.
Robert B. Darnell is Senior Physician and Professor of Molecular Neuro-Oncology at The Rockefeller University, Investigator at the Howard Hughes Medical Institute, Senior Visiting Scholar at MITER, and Founder and Founder of the New York Genome Center. Honorary CEO. .
