Through these frenetic months, the Pac-12 has been a frequent visitor to the edge of major-college athletics.
It was the only major conference to postpone the basketball season until January (and then reversed course).
It was the only major conference to deal with the double whammy of wildfires and state restrictions.
It will be the last major conference to return to the field — two weeks later than the Big Ten.
And now, as Week One approaches, the Pac-12 is again an outlier — only this time, it seems, in a good way.
The conference’s COVID-19 testing program is extreme.
“It’s very aggressive,’’ commissioner Larry Scott said. “But it gives us the best chance possible to get through the season with a minimum number of lost games.”
Those lost games are piling up in other conferences as another coronavirus wave rises nationally.
There were six postponements last week alone, including LSU-Florida and Oklahoma State-Baylor.
This weekend, the Big Ten returns to play with a nine-game schedule that has no bye weeks for makeup games.
On Nov. 7, the Pac-12 will commence its quest to play seven games in seven weeks.
What are the chances it avoids disruption? Pretty good, actually.
The Pac-12’s testing program is unlike any in college football, a mix of daily antigen and PCR tests designed to snuff out spread, reduce the need for contact tracing, keep quarantine levels low and allow the season to unfold uninterrupted.
Each day the players take the field for practice or games, they will be tested using traditional PCR tests or the rapid-response antigen tests supplied by Quidel Corp.
It’s not perfect, but scientific data and computer modeling suggest it’s closer to perfection than any testing program currently deployed.
“It’s a great plan,’’ said George Rutherford, a UCSF professor of epidemiology and biostatistics. “It’s more than adequate. But the question of testing is one thing. The other part is, you have to not get infected.
“Testing will cut down on disease transmission, but it’s also about staying safe and (players) not putting themselves in situations where there is transmission.”
The Pac-12 won’t get through the season without positives cases. The medical advisory committee knew that before recommending the resumption of contact sports, and the presidents knew it before approving the return to play.
The propensity for college students to socialize is as unstoppable as the virus itself.
But what happens after the player becomes exposed to COVID?
The testing plan published by the conference was built to stop the virus from taking the field:
“Based on evolving science, we recommend once a week PCR testing supplemented by point-of-care antigen surveillance the day of higher risk of transmission activities, including pre-competition.”
In a typical week, players will be tested daily Monday through Saturday, with at least one PCR test. Schools can add a second PCR test if desired, or if recommended by local health authorities (because of levels of community spread).
Each team is equipped with the capacity to conduct multiple PCR tests per week, in addition to the daily antigen tests supplied by Quidel Corp.
Per conference policy:
Any player with a positive antigen test will be isolated “and a confirmatory PCR test would be performed. Discordant results would prompt evaluation of the cycle threshold (Ct) values and repeat PCR testing to determine further disposition in consultation with an infectious disease expert.”
PCR tests are used for confirmation because they’re more accurate and more sensitive — that is, they identify lower levels of virus particles than do the antigen tests.
But they also require more time for results, because the sample must be sent to a laboratory and cycled through a detection machine.
PCR tests are for personal care: Does a specific individual have the virus?
Antigen tests, on the other hand, are a public health containment measure: The frequency of use and speed of response — they don’t require a laboratory — combine to limit spread.
Colorado scientists Daniel Larremore and Roy Parker recently co-authored an article for the New England Journal of Medicine (NEJM) with Harvard epidemiologist Michael Mina.
Titled “Rethinking Covid-19 Test Sensitivity — A Containment Strategy,” it includes the following section:
“Clinical tests (PCR tests) are designed for use with symptomatic people, do not need to be low-cost, and require high analytic sensitivity to return a definitive clinical diagnosis given a single opportunity to test. In contrast, tests used in effective surveillance regimens intended to reduce the population prevalence of a respiratory virus need to return results quickly to limit asymptomatic spread and should be sufficiently inexpensive and easy to execute to allow frequent testing — multiple times per week.
“Transmission of SARS-CoV-2 appears to occur days after exposure, when the viral load peaks. This timing increases the importance of high test frequency, because the test must be used at the beginning of an infection to stop onward spread, and reduces the importance of achieving the very low molecular limits of detection of the standard tests.
“By several criteria, the benchmark standard clinical polymerase-chain-reaction (PCR) test fails when used in a surveillance regimen. After collection, PCR samples typically require transport to a centralized lab staffed by experts, which drives up costs, drives down frequency, and can delay results by one or more days. The cost and effort required to get tested with a standard test mean that most people in the United States have never received one, and slow turnaround times mean that even when the current surveillance approach does identify infected people, they can still spread the infection for days before notification, which limits the impact of isolation and contact tracing …
“Lateral-flow antigen tests do not have an amplification step, so their analytic limits of detection are 100 or 1000 times higher than that of the benchmark test, but that is largely inconsequential if the goal is to identify people who are currently transmitting virus. SARS-CoV-2 is a virus that grows quickly inside the body, so by the time a benchmark PCR test becomes positive, the virus is well into exponential growth. At that point, it is probably hours, not days, before the virus grows by orders of magnitude, reaching the detection thresholds of currently available cheap and rapid point-of-care tests. It is after this point, when people would have positive results on both tests, that they would be expected to become infectious.
“We believe that surveillance testing regimens that can sever enough transmission chains to reduce community spread should complement, not replace, our current clinical diagnostic tests. Imaginative strategies can take advantage of both kinds of tests, using frequent, cheap, and rapid tests at scale to mitigate outbreaks, with positive results confirmed using a second rapid test targeting a different protein, or using a benchmark PCR test.”
The approach outlined in the NEJM article is similar to the containment strategy being deployed by the Pac-12:
Six tests per week, most of them being rapid-response tests but at least one “using a benchmark PCR test.”
How does the Pac-12’s weekly testing plan compare to those of other conferences?
ACC: three tests per week (two PCR)
Big Ten: daily antigen tests
Big 12: three tests per week (two PCR)
Pac-12: every day of competition (one PCR)
SEC: three per week (all PCR)
(Note: Some schools are testing more frequently than the baseline standards established by the respective conferences.)
The difference in sensitivity between PCR and antigen tests is relevant to the broader strategy.
According to Rutherford, PCR tests can detect the virus at minute levels — 500 parts per milliliter.
An infected person, on average, is carrying viral loads at 10-to-the-7th parts per ml.
In other words, PCR tests are more sensitive than what’s needed for containment, in addition to requiring longer turnaround time.
Antigen tests detect particles at a higher concentration than PCR tests but, according to Rutherford, still identify the virus at levels “well short of what’s need for infectiousness.”
The conference is trading more sensitive, slower tests for less sensitive, speedier tests — the latter being more effective at driving down spread.
The following chart, used by the Pac-12 medical advisors to craft the testing strategy, is based on computer modeling by Larremore and Mina:
Because of the 24-hour turnaround time required of PCR tests, positive cases can slip through, especially if testing is every other day.
The viral load could grow exponentially after one test is conducted but before the results of the subsequent test are known.
But the results of antigen tests are available within an hour — just before players take the field for practice or competition.
If the viral load isn’t high enough to register a positive result, the player won’t be contagious for the two- or three-hour period when he’s on the field.
Does this mean the Pac-12 testing plan is better than those deployed by other leagues?
The modeling suggests it is, especially when a second PCR test is added to the required regimen.
However, our analysis would be remiss if we didn’t mention that antigen tests are not as accurate as PCR tests.
There have been numerous reports of false positives with the Quidel tests. But those should be corrected by the confirmatory PCR test (per Pac-12 protocol).
And if the goal is containment, then a false positive is the least of the conference’s concerns.
But what about the potential for false negatives in asymptomatic or pre-symptomatic players?
The likelihood of spread would be mitigated by the second weekly PCR test most teams are expected to administer and the antigen test conducted the following day.
“These testing regimens are designed to work by repeated testing, so that those who don’t get identified during one test get picked up the next day,” Larremore explained.
“They stack up, like the layers of a filter, to provide the effect of breaking transmission chains before they get out of control.
“Concerns about false negatives are reasonable. However, the advantage of the rapid tests is that you can test everyone right before the game, instead of the day or night before.
“This means that you’re balancing testing people as close as possible to game time with that false negative possibility.”
The Pac-12’s plan, it seems, is sound — as sound as any in major-college football.
“It’s more than adequate,” Rutherford said. “The test is the diagnostic piece. There is also the behavioral piece.
“It’s not going to propagate through the team, unless they all go to the same frat party.”