What Happened to COVID-19 Testing?

They are everywhere, ghosts in a shell. Many of them stained in the malaise that besets makeshift Halloween stores in November.

With vaccination rates at all-time high, testing centers are seeing fewer and fewer patients. Some retail pharmacy chains in certain parts of the country have stopped testing people altogether.

According to the COVID-19 Tracker database, COVID-19 tests fell by 10% in the second week of March 2021. But the number of positive cases also fell by 12%, which continues a now two and a half (2.5) month long trend of declining national positivity rates.

As with most things related to the pandemic, we conflate what is happening now with what will happen in the future. So when we see positivity rates dropping, and the number of vaccinations increasing, we assume testing is no longer necessary – or at least as important.

In effect weighing vaccinations against COVID-19 antigen tests – presuming that if we are getting vaccinated then we do not need to get tested.

Yet states continue to primarily use positivity rates in determining whether to lift economic restrictions and social distancing guidelines – whether to reopen businesses or to increase in-person occupancy rates for recently opened businesses.

Positivity rates are calculated a number of ways, but the Centers for Disease Control (CDC) has identified four broad methods through which states can calculate positivity rates:

1. The number of people who test positive with molecular (such as PCR) tests divided by the total number of people tested with molecular tests.

2. The number of people who test positive via molecular test divided by the number of people tested with molecular tests, with multiple tests on the same person removed, at different frequencies ( days, weeks, etc.), depending on the state.

3. The number of positive molecular test results divided by total molecular tests given.

4. The number of people who test positive is divided by either by unique people, encounters, or tests (depending on availability – each variable can help indicate the number of people tested).

While each state calculates positivity rates differently and at its own discretion, the four approaches describe the general methods used by all states. Each heavily configuring the total number of tests administered into the calculations.

Which means the total number of people tested affects the positivity rates. More importantly, which means the vaccination rates do not impact positivity rates.

While we can assume that higher vaccination rates equate to lower positivity rates – and the current trends certainly suggest as much – we cannot know with certainty what the true positivity rate is unless we continue to conduct the required number of tests per day – which varies based upon the population of each state.

Ideally, testing would increase with vaccination rates, in order to verify the lower positivity rates, but it is quite the opposite.

In the first two weeks of March 2021, the number of people tested decreased by one million each week. Previously this may not have mattered much, as multiple national databases have shown that over the course of the pandemic, declining testing rates have not correlated with decreasing positivity rates.

More specifically, although the number of people tested affects the calculation of positivity rates, the trends in testing rates have not affected the trends in positivity rates – so far.

But a recent analysis conducted by Nephron Research over the COVID-19 Tracker database suggests a newly forming relationship. One that began when we started administering vaccines, implying that increasing vaccination rates have changed the association between positivity rates and the number of people tested – from having no correlation to being directly correlated.

While this trend may prove true in the remaining months of the pandemic, it is still too early to verify, as we have begun ramping up vaccination rates only recently, starting in January 2021. States are still in the middle of the relaxing the restrictions, using positivity rates to guide the timeline for this process.

If we are to optimize this process, ensure we thread the delicate balance of opening the economy while minimizing the number of unnecessary (or excess, avoidable) deaths, then we should be keen to maintain an accurate reading on the positivity rates. The precision in these policy decisions depends upon the validity of the data.

While the metric is flawed, the positivity rate is the best measure we have to determine the spread of the virus, and to predict the likelihood of a potential outbreak. Something we are starting to see in European countries, particularly in Italy, as the continent is immersed in a fourth wave of variant-driven COVID-19 cases.

And if past trends seen during this pandemic hold true, then what happens in Europe, will happen in the United States within a few months.

The positivity rates will reveal if and when this will happen. But the positivity rates are only as accurate as the number of people being tested, which makes it imperative that we continue to encourage symptomatic people to get tested, and not allow the recent perceived successes of the vaccines to lower our guard.

Throughout the pandemic, we have misinterpreted and reinterpreted data, making faulty policy decisions one after another. If there is one thing we can improve upon in the latter weeks of the pandemic, it is our ability to extrapolate meaningful interpretations by improving the accuracy of the data we collect – improving our ability to make policy decisions.

Vaccination rates do not correlate with positivity rates. Just like positivity rates do not correlate with herd immunity. There may be times when different trends appear to move in the same direction, and it may seem that right now we can make decisions or create assumptions about positivity rates relative to vaccination rates, but short-term aberrations are distinctly different from long-term correlations.

When we change how we collect data, we change the data itself, altering the validity of the data along the way. Perhaps positivity rates are no longer the best metric to determine whether to relax economic restrictions. But we will only know this if we continue to test for COVID-19, and continue to monitor the positivity rates as we have been throughout the pandemic.

Europe is mired in its fourth wave, and we have every reason to believe that what is going on there will happen here. We need to remain vigilant and continue to trace the positivity rates. This metric has proven in the past to be the most effective measure of calculating viral outbreaks, and the most valuable in gauging the effectiveness of social distancing policies.

If we hope to predict future trends in the coming months, then we should maintain consistent standards in how we populate the data throughout the pandemic, from start to finish.

So we can get to the end of the pandemic safely, and hopefully more quickly.

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Vaccine Passports: what we need to know

The COVID-19 pandemic has killed more than half a million people in the US and has seriously impacted our daily lives. The granting of Emergency Use Authorizations for COVID-19 vaccines has been a game changer in helping to reverse the pandemic onslaught. Demand for the vaccines currently far exceeds supply nationwide. They have become the golden ticket that can transport us back to a time when routine activities, such as attending school or taking vacations, didn’t seem fraught with danger. What’s the best way to go about re-establishing these activities? One idea that’s getting discussed seriously is giving those who have been immunized a vaccination passport (VP).

What is a vaccination passport?

Let’s start by clarifying some terminology. VPs are documents that show that someone has been given a vaccine(s) and is therefore presumed to be immune from getting and sharing that disease. These are distinct from diagnostic tests to determine if a person is or is not infected with a particular virus (PCR and viral antigen tests) or has been exposed to a virus (antibody tests). VPs are the modern day equivalents of the “letters of transit” that played a key role in the film Casablanca. They’ll enable you to travel freely.

Why give vaccine passports?

Vaccinated people are unlikely to transmit the virus that causes COVID-19 with others, though this has yet to be definitely proven. So, what’s the primary rationale for giving vaccination passports? It seems the goal is to incentivize people to get vaccinated. Folks might be more likely to seek out the vaccine if it bestows upon them certain privileges, such as being able to travel freely. While the idea might sound appealing at one level, the road to vaccine passports is pockmarked with political potholes and littered with logistical land mines.

Administrative issues

There are a lot of important questions that need to be answered before VPs can become widespread; it’s unlikely there will be a “one size fits all” solution. What might VPs look like? Pieces of paper (that could easily be lost or counterfeited), or a digital key or document you store on your smartphone (that many older folks still don’t have)? If you lost one, how would you get it replaced? Would your vaccination records be tied to your other medical records, and if so, what kind of privacy and security protections would be needed to safeguard your data? How would the passport administrator verify that you got vaccinated in the first place? Who is responsible for correcting any errors that crop up? Given how much we’ve struggled as a nation to simply solve the scheduling of vaccinations, VPs might be significantly more difficult to manage.

Who’s going to run the program?

A coalition of health tech leaders (including Epic, the Mayo Clinic, Microsoft and Salesforce) has started the Vaccination Credential Initiative to create an internationally accepted digital health card. Its vision – as stated on its website – is “to empower individuals to obtain an encrypted digital copy of their immunization credentials to store in a digital wallet of their choice. Those without smartphones could receive paper printed with QR codes containing World Wide Web Consortium (W3C) verifiable credentials.” Some European countries (e.g. Denmark) are working on developing their own immunization passports, and the President of the European Union Commission has voiced support for them.

We already have a hodgepodge system designed to keep folks with COVID-19 from traveling. Many airlines are requiring proof of non-infectivity to board a plane – these are distinct from VPs. The methods adopted vary from airline to airline: United uses Travel Ready Center, American uses VeriFly while others use Common Pass. Saga cruises are the first in the UK to demand proof of vaccination, but not everyone is on board with the concept. The World Travel and Tourism Council stated its opposition to allowing travel only by those who have been vaccinated, on the grounds that it is discriminatory.

Discrimination concerns

The concept of gaining advantage from one’s immunological status is not a new one. In New Orleans in the mid 19th century, great economic value was attached to those who survived the onslaught of epidemic waves of yellow fever. A mix of structural racism and a system valuing “immunocapital” ranked men and women highly if they were yellow fever survivors. Those that had not had the disease yet found it difficult to obtain work or obtain credit and women could not marry. Slaves were similarly revalued, with larger assessments attached to survivors. This legacy of viral discrimination casts a long shadow over current discussions surrounding vaccination passports.

Also problematic is the fact that not everyone will be eligible for VPs. Some people can’t be vaccinated for medical reasons but would still like to participate in whatever activities the passports enable (such as travel opportunities). These individuals will likely file complaints if they are denied VPs, arguing that they’re discriminatory in nature. Vaccine opponents will no doubt also file lawsuits seeking to block the use of VPs, claiming they represent an attack on their freedoms and personal choice.

Others may be shut out of VP programs because they don’t have the computer skills to register online, a problem that’s turned out to be widespread with the vaccinations. Don’t have any ID? In some places this prevents the most vulnerable from getting the COVID-19 vaccine, and therefore VPs as well. Many Black and marginalized communities are already deeply suspicious of the medical establishment, and wary of receiving a COVID-19 vaccine. Restrictions that prevent these groups from participating in various societal activities because they don’t have VPs will echo the Jim Crow days of poll taxes and literacy tests that were required to vote.

Enforcement issues

VPs bring up a similar issue as mask mandates: who is going to enforce them? It is one thing for a cruise line to do so, since reservations are required and extensive paperwork needs to be filled out in advance. Who is going to keep non-vaccinated people out of restaurants or concerts that require proof of vaccination? We’ve already seen anti-maskers storm department stores, ignore requirements to wear masks on planes and even kill a security guard who confronted them.

Black market for vaccine passports

Many airlines are now requiring proof of a negative COVID-19 test before they will let their customers fly. This has led to a black market for fake negative COVID-19 test results for those who are looking to game the system. Similarly, bogus cards claiming that the cardholder was exempt– for medical reasons – from having to wear a mask, have been manufactured and distributed. It’s not hard to imagine that a similar market will emerge for VPs.

Overcoming vaccine hesitancy

Given the multitude of issues and concerns listed above, moving forward with issuing vaccination passports seems highly problematic. If the primary purpose of having VPs is to drive up immunization rates, that can be better accomplished by running public service announcements and ads illustrating how liberating it is to start doing normal activities once vaccinated. A nationwide campaign to do just that is already in the works. I personally can think of a better use for the time and money that will be spent on establishing VPs: use them to focus efforts on overcoming vaccine hesitancy in concert with combatting the high tide of online vaccine misinformation and disinformation.

Source: Technology Networks

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