Many critics were concerned that the CDC did not mention rapid antigen testing to confirm that people infected with COVID-19 aren’t contagious when it revised last week its guidelines for Americans who have recovered from the disease. Yesterday, the CDC responded to that concern by adding the following advice.
If an individual has access to a test and wants to test, the best approach is to use an antigen test towards the end of the 5-day isolation period. You should only collect your test sample after you have been fever-free for at least 24 hours and without any fever-reducing medications. Other symptoms may also be improved. You should isolate yourself until the test results are positive. If your test result is negative, you can end isolation, but continue to wear a well-fitting mask around others at home and in public until day 10.
The CDC has not yet recommended that individuals who have been in isolation take antigen tests prior to returning to work or other normal activities. The CDC’s guidance is restricted to people who can get a kit to test for antibodies and have the desire to use them. This is quite puzzling as a negative result gives you additional confidence that you will not infect other people. However, a positive test results, which the CDC recognizes, suggest that it is wise to continue isolation.
According to the CDC, people may not have access to a test even if it is requested. The reason the CDC has been recommending home testing in the United States, two years after the outbreak, seems to be that they remain more difficult and expensive than in other countries. Its confusion stems primarily from the Food and Drug Administration’s reckless foot-dragging. Rochelle Wilensky, CDC Director, has also questioned the reliability and validity of antigen test results.
Walensky stated that they chose not to use the rapid test for isolation as we don’t have any information about how the tests work or how accurate they can predict whether you will be transmissible at the end of the disease. They have not been authorized by the FDA for this purpose. She even stated that the antigen testing results would not prove useful in an interview with NBC.
This is contrary to what the CDC claims. The CDC’s latest guidance states that a positive test for antigen does give useful information and warrants continued isolation. The CDC states that a negative test result can provide useful information to those who take it. It means, “you have the ability to end isolation.”
As New York TimesZeynep Tufekci, columnist notes that Walensky’s rejection of antigen testing also goes against her views before becoming head of the CDC. Walensky, a Harvard Medical School professor who was also the chief of Massachusetts General Hospital’s infectious disease section, co-authored an article in September 2020. Health AffairsAn article which compares antigen testing, which can detect viruses on the coronavirus’ surface and give fast results at-home, with polymerase chain reaction tests (PCR) which require a doctor visit to confirm the detection of genetic material.
Walensky and Paltiel at Yale School of Public Health wrote that “it turns out the PCR-based nose swab used by your caregiver in the hospital does a great deal to determine if you’re infected.” However, it doesn’t do a good job of pinpointing whether you might be infected. The rapid saliva-based antibody test, which has a 30 percent false positive rate, does not diagnose infection well, but is a better way to determine infectiousness.
The problem with someone who has recovered from COVID-19 infection is the ability to judge infectiousness. It is also about deciding whether they are able to safely mix and mingle. Tufekci recommends that you use rapid tests to assess infectiousness. This is because false positives are most likely to be people with low viral loads.
Tufekci draws a parallel between CDC’s attitude to antigen testing and the CDC’s early resistance in masking, which was a way of protecting against transmission. Although public health officials stated that there wasn’t enough evidence for face mask use, they soon realized their true concern was the scarcity of quality masks. They believed these masks should only be used by health workers. In this case, the U.S. is facing a government-engineered shortage of rapid antigen tests. The CDC has decided to rationalize its testing advice, arguing that tests may not be as useful as they claim, rather than stating this fact outrightly.
Walensky’s handling this issue shares a lot with the CDC’s previous misrepresentations about COVID-19 science. They often appear to be motivated by a desire for defending whatever agency position they are taking. Although Walensky has been a source of unreliable information on COVID-19 several times, this problem is not new.
The agency quickly went from dismissing the value of face masks to describing them as “the most important, powerful public health tool we have.” Robert Redfield (the predecessor of Walensky), argued that face masks are more efficient than vaccines. Walensky suggested something very similar. He exaggerated the evidence to favor masks, which implicitly denigrates the effectiveness of vaccines, particularly in the prevention of severe illness and death. To this day, the CDC advice on face coverings stresses the importance of a fit while not mentioning the significant differences in effectiveness among different mask types.
All of these factors do not inspire confidence in the agency Americans can trust when there is a pandemic. The CDC’s record of making misleading statements, and weakly justifiable reversals certainly did not inspire confidence in the agency when it decided to decrease the recommended isolation time by half.
The CDC stated that this change was driven by “science demonstrating that SARS-CoV-2 transmission is most common in the early part of illness. Generally, it occurs within the 1-2 day prior to onset symptoms. It usually happens in the 2-4 days following.” This gloss admits that Some Transmission occurs within five days. However, this point does not mean that the transmission is complete. Other factors must be taken into consideration when advising the public.
Anthony Fauci (President Joe Biden’s COVID-19 top adviser) and Walensky noted that an isolation period of 10 days can have very negative effects on the economy. This is particularly relevant in the context of the current omicron surge. Fauci explained that “on balance,” he said “if you consider the safety of people and the need to keep society from being disrupted, it was a good decision.”
Fauci and Walesnky also pointed out that the isolation of 10 days was far more than many people could or would tolerate. Walensky explained that “it really did have a lot in common with what people could tolerate.” We wanted to ensure that guidance was available in the moment we realized we would be dealing with a lot more disease.
It is important to consider this. It is wrong to be too cautious if your recommendations are widely ignored. If people follow the guidelines, they are likely to accept some risk. Guidelines with higher tolerances for transmission may be better than those that target zero risk. Fauci said, “You don’t want perfection to be an enemy of the good.”
Much of the criticism that the CDC’s guidelines evoked was unfounded. MSNBC columnist Hayes Brown said that “Walensky & Fauci made it seem like the CDC’s decision was not based on science” by including employer and societal requirements in their arguments. However, the CDC advice was never “based purely on science.” It shouldn’t be.
Value judgments and cost-benefit analyses are essential components of any recommendation on how to address the contagious diseases threat. That is fine as long as the CDC is open about its science and candid about what it is considering. It should also be willing to acknowledge that different people may reach different conclusions depending on risk tolerance and personal preferences.
The CDC has often failed to meet one or more criteria. This is evident in its testing recommendations. Antigen testing is a valuable tool, even if it’s imperfect in reducing transmission risk and allowing individuals to return to normal living, as Walensky said once. Recommending their use toward the end of isolation—instead of simply granting that some people might “want” to use them, apparently for idiosyncratic, unscientific reasons—seems commonsensical. The CDC might be able to regain credibility by recommending their use.