Tracking Delta breakthroughs ... Part 4 (Mitigation via testing and contact tracing)

Last update: Sunday 9/5/21

Why don't we know how many Delta  breakthrough infections occurred last month and where? Why don't we know which population segments are most likely to be infected by Delta, even if they have been fully vaccinated? Are cloth masks as effective in suppressing the spread of Delta as they were in suppressing previous variants?  Are breakthroughs more likely because (a) Delta is more transmissible, (b) vaccine effectiveness weakens after six to eight months, (c) encouraged by the CDC in May 2021, many people abandoned their mitigation habits just as Delta was becoming the dominant variant, or (d) some combination of (a), (b), and (c)? 

When asked these and other questions of comparable importance, most experts blither about "uncertainties" in "the science". They rarely admit that they don't know the answers because the CDC and its state level affiliates aren't collecting the kinds of data that would provide reliable answers.

Inadequate data leads to policy conflicts wherein one side pessimistically advocates policies that assume the worst possible outcomes vs. the other side that cautions that we should wait until the inadequate data affords greater clarity. 

A recent example

For example, in mid-August, 2021, President Biden declared that his administration would begin to push booster shots for everyone in September. He assumed that vaccine effectiveness against severe illness and death will soon weaken, thereby enabling massive waves of the worst kinds of breakthroughs. Many experts disagreed. 

Two top FDA officials resigned in protest against the president urging booster shots before the FDA reviewed the available data and gave its approval, or not. The backlash spread throughout the public health community. Within a few days of these high profile resignations, the directors of the FDA and the CDC, both of whom had previously supported the president's initiative, flip-flopped; both of them notified the President's office that it should scale back its booster plan for now.

• "Biden Ramps Up Virus Strategy for Nursing Homes and Schools, and Urges Booster Shots", Sharon LaFraniere, Sheryl Gay Stolberg and Erica L. Green, NY Times, 8/18/21 
  
  
• "Two Top F.D.A. Vaccine Regulators Are Set to Depart During a Crucial Period", Noah Weiland and Sharon LaFraniere, NY Times, 8/31/21  
  
  
• "Health Officials Advise White House to Scale Back Booster Plan for Now", Sharon LaFraniere and Noah Weilan, NY Times, 8/3/21  

We could continue to lurch from one CDC flip-flop to the next ... or we could pay attention to more effective mitigation policies based on systematic data derived from more extensive testing and contact tracing. 

Ideally, the public health agencies in each of the 50 states plus major U.S. territories would have established intensive testing and contact tracing operations shortly after the pandemic began back in early 2020. Ideally, the CDC would coordinate the assembly and dissemination of this local data. For various political reasons, this didn't happen under President Trump; and for similar political reasons it's not going to happen under President Biden. 

Systematic data about workplaces

Fortunately, numerous employers in the public and private sectors are likely to launch extensive testing and tracing programs in the coming months. We should expect to see these programs appearing in sectors wherein prior pandemic experience indicated that indoor face-to-face encounters are essential, e.g., K through 12 schools, colleges and universities, airlines, cruise liners, nursing homes, hospitals, and other health care facilities. 

Hopefully, the media will publish the results of these programs; and hopefully, the CDC will focus the nation's attention on the most significant results. Of course systematic data about workplaces will not be as useful as systematic data about entire communities; but it will provide more reliable insights than non-systematic, i.e., anecdotal data at any level.

In each workplace, administrators will use the results of their testing and tracing to make appropriate adjustments to the mitigation policies they impose on their key staff, support staff, and clients. For example, an elementary school's key staff would include its teachers; its support staff would include administrative assistants, secretaries, and maintenance workers; its workplace clients would include its students.

Here are a few conditions that successful workplace testing and tracing programs must satisfy:

• Administrators must test both vaccinated and unvaccinated members of a workplace from time to time, preferably every week.
  Most Delta breakthroughs will have no symptoms or only mild symptoms; nevertheless they can spread Delta as easily as unvaccinated persons who become infected ... which means they must be tested in order to identify them while they are contagious
  
  In July 2021, President Biden declared new rules and incentives to encourage unvaccinated federal employees to get vaccinated. Specifically, he will impose periodic testing on unvaccinated employees; but vaccinated employees will not be tested. In other words, periodic testing will be a punishment for not becoming vaccinated. His new rules guarantee that most breakthrough cases will not be identified. His new rules will also reinforce the urban legend that the recent surge in Delta infections is solely due to the hesitancy of unvaccinated persons to become vaccinated, a legend because by now everyone should know that breakthrough cases can easily spread Delta. That's why they are so disruptive.
  
  -- "Biden Seeks to Revive Vaccine Effort With New Rules and Incentives",  Michael D. Shear, Sheryl Gay Stolberg and Annie Karni, NY Times, 7/29/21 
  
  
• Administrators who test everyone in the workplace don't have to conduct contract tracing
  If all of the key staff, support staff, and clients are tested, then contact tracing will not provide any useful additional information. If no one tests positive, the workplace might continue to rely on masks and social distancing. If only a few members of the workplace are infected, they might be directed to go into quarantine at home or in some other designated facility for a couple of weeks, i.e., until they were no longer contagious. 
  
  But if a substantial percentage of the workplace participants are infected, the administrators might have to direct everyone to shelter at home. For example, if the workplace were a school, college, or university, the administrators might have to cancel all face-to-face classes and resume remote Zoom classes for the rest of the semester. The Los Angeles school system provides a recent example of this kind of universal test program 
  
  -- "In Los Angeles, price for admission at nation’s second-largest school district is a negative covid test — every single week",  Erica Werner, Washington Post, 8/29/21 
  
  
• Administrators who only test subsets of their workplace participants must also conduct contact tracing 
  The goal being to identify all contagious participants, a sample would be highly unlikely to include everyone who had been infected recently. However if every positive participant in the subset identified all of their recent contacts, it's likely that at least one of their contacts will also test positive. The positive contacts will then be interviewed and asked for their recent contacts. etc,. etc. etc
  
  Programs that followed testing with contact tracing were implemented by two hospitals in San Francisco. Most of the detected infections were Delta breakthroughs.
  
  -- "More than 200 staff members at 2 San Francisco hospitals have tested positive, most in breakthrough Delta infections.", Eduardo Medina, NY Times, 7/31/21 
  
  Testing followed by contact tracing and quarantines were also implemented by a cruise line. 26 crew and one passenger, all vaccinated, tested positive and were quarantined.
  
  -- "Cruise Passenger Dies From Covid, Testing Industry Plans", Ceylan Yeginsu, NY Times, 8/23/21 ... Note: the passenger was vaccinated

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Related notes on this blog:

• "Downgrading the CDC's guidance", Last update: 7/25/21
     
• "Is the CDC misguiding us again, this time with regards to Delta breakthrough infections???", Last update: 8/13/21
  
  
•  "Tracking Delta breakthroughs -- Part 1 ) Three disruptive properties)", Last update: 8/21/21
  
  
•  "Tracking Delta breakthroughs -- Part 2 (Mitigation via masks)", Last update:  8/22/21
  
  
• "Tracking Delta breakthroughs -- Part 3 (Mitigation via distancing)", Last update:  8/31/21