The crisis of unreported COVID-19 cases

There are few places in the world where the Omicron COVID-19 variant has not permeated headlines with surges in case numbers. Something that caught my eye, in particular, was a phrase that tends to repeat itself, regardless of geography, time period or significance of case numbers:

COVID-19 cases are 12 times higher than reported (MIT, 2020)

The Kirby Institute has said the number of COVID-19 cases could be up to five times higher as many are going unreported. (9 News, 2022)

US COVID cases likely more than double official count, experts say (CIDRAP, 2020)

For the outbreak of March-July 2020 in Rio de Janeiro, we estimate about 90% of unreported cases (medRxiv, 2020)

Up to 60% of U.S. Covid-19 Cases Unreported, Disease Model Says (Bloomberg, 2020)

1 in 4.0 COVID–19 infections were reported (CDC, 2021)

Naturally, a few important questions are raised by unreported COVID cases:

1. What is even the importance of estimating the correct number of COVID cases in the first place?
   This one is fairly simple (but you can scroll to the bottom of this link to find out more) — today’s infection numbers impact not only public policy responses and community behaviour, but are also used for predictions of future cases (which, of course, predict the same type of behaviour).
2. What are the main causes of the under-reporting of COVID cases?
3. Why is any of this a problem?

This article will aim to provide a fresh perspective on the last two questions, focusing mainly on the data-collection issues that underscore our COVID-case reporting protocols, but also on how policy decisions might impact this for the better or worse.

Source: Bianca de Marchi/AAP

Causes of under-reported COVID infection numbers

As could be clearly seen from the quotes at the beginning of this piece, much well-thought out research has been conducted into whether under-reporting exists — in fact, statistical models seem to unequivocally suggest the presence of this phenomena. The more intriguing and under-researched questions seems to be — why are numbers under-reported?

While certain reasons are suggested by the CDC in the link above, I would suggest that the main ones, especially considering the context in Australia, are:

• A patient receives one (or more) positive Rapid Antigen Tests and does not feel the need to confirm this result with a PCR test (see the difference here), meaning this is not added to the official count
• A patient, despite admitting that they have a high likelihood of having COVID-19 (eg. due to severe symptoms and having a close contact), chooses not to take a test and instead self-isolates for 7 days
• A patient does not have the means to travel to or attend a test (eg. cannot travel to a testing location, is not provided sufficient information, personal reasons)
• Unreliability of national data figures (I suspect this would not be much of an issue in Australia, but this has been discussed extensively between US/China — see here)
• Several other minor reasons, such as false positives and testing centres exceeding their capacity.

Why is any of this a problem?

The most obvious issue brings us back to our first question — why is getting the number right in the first place important? If the correct reporting of cases leads to strong decision-making from policy-makers and astute judgement on the part of laypersons, then under-reporting of cases will naturally imply clouded policy-making and complacence from the public, something the Australian people are no strangers to.

But perhaps more importantly, the failure to report cases can also pose an immediate threat to the person who is not reporting the case themselves. As this might sound very confusing, I’ll provide two clear examples from the dot points above.

Patients receiving Rapid Antigen Tests who don’t confirm their result with a PCR test

Leading up to the 6th of January (in Victoria at least), the government would only be informed of a positive COVID-19 case through an official PCR test. As RATs were so popular across the country, and PCR tests would often take hours at a time to complete, many would simply take a positive RAT as given, and not confirm this case with a PCR test, thus not leading to their case being counted as official, but more importantly, not allowing their case to be reported to official contact tracing sources (thus, potentially not preventing an outbreak). For example, consider the poll below:

Source: @thedailyaus (Instagram)

This means that in a fairly significant sample, almost 42% of individuals did not have their cases officially reported — many of whom would have never spoken to the authorities about their condition.

But, since the law has since changed to since allow individuals to report their positive RATs digitally, this problem would largely be solved… Right?

Perhaps; but the same question lingers — what incentive does someone have to report their case? My view is, unless if there exists or emerges an obvious benefit to individuals to notify the authorities of their illness, there will continue to be a significant proportion of rapid-antigen positive individuals who the authorities have no idea of; thus not warping the number of new infections we see every day, but drastically undermining the efficacy of the government’s rigid contact tracing protocols. Remember — in a bar of 100 people, if even 1 person does not follow proper contact tracing rules and ends up being COVID-positive, they could place in jeopardy the moral actions of the other 99.

Patients who do not have the means to get tested

Much research has been conducted into the varying impacts of this pandemic on communities of different levels of affluence. I decided to bring this a little closer to home by looking at how many infections each LGA (Local Government Area) had as a proportion of their population, compared with the LGA’s median income.

Source: Analysis performed on data from ABS (median income, 2018–19) & DHHS (cases by LGA, 3/1/2022)

While there are outliers to the trend, there is at least some relationship between the median income and percentage of infectious individuals in an LGA. The regression coefficient exhibits a p-value of approximately 0.02, making this relationship statistically significant at a 5% level. The regression equation indicates that for a $1000 increase in median income in an LGA, on average, we expect a 0.11% increase in the percentage of infectious individuals in an LGA. Again, this is not anything to write home about, but it’s not nothing, either.

So, there is some relationship between the percentage of people testing positive and the median income of that area — but why? There are only two possible explanations:

1. More affluent individuals are more prone to catching the virus (eg. they go out more, or go out to more exposure sites, than those who are less affluent)
2. More affluent individuals are more likely to get tested (eg. are more medically conscious, or are located in LGAs where testing is more accessible)

While the first may be true, my mind was immediately drawn to how big of a problem the second is. When myself and my friends (who I consider to be relatively lucky in the grand scheme of things) consider that we might have COVID-19 due to some reason or another (eg. having a close contact, symptoms resembling those of the virus), I think of how my actions might compare to someone who is in a situation less well off than myself or my peers:

• If I’m out, I get someone I know well to drive me home, double-masking in the car and avoiding any physical contact. But, this may not be possible for someone who does not have close friends or family to transport them, and cannot afford private transport such as an Uber. This is not to mention those who do not have access (or the need to access) radio, televisions or the internet to keep updated with health advice (eg. the definition of close contacts, types of tests and testing locations)
• I’ll self-isolate at home and perform Rapid Antigen Tests. But this may not be possible for individuals who live in smaller spaces and cannot afford to reserve an entire space to themselves, and for those who cannot afford or access RATs
• Usually the next morning, I’ll drive out and get a PCR test. Once again, many people either cannot drive or may not be well enough to drive, and might not have anyone to take them. And while I’d possibly wait hours in the process, many people do not want to take critical time off work, or cannot afford to leave their dependents alone
• I’ll then self-isolate until I receive my test result, having the luxury of food being brought to me and any sanitary equipment that I need at my disposal. But, many cannot afford food delivery services, or do not have others to cook food for them while they are in isolation, or have no other way of receiving critical supplies without leaving their home and jeopardising others

Being through this process a few times has unveiled how incredibly blinding many of our situations of privilege can be and how this pandemic disproportionately impacts those in vulnerable situations.

A note on the recent policy response (written after the initial publishing) — reporting a positive rapid test can again only be done over the phone or on the internet. This means that someone not only needs to be able to access the test in the first place, but needs to have access to either a phone/internet (eg. 9% of Australians do not have access to home internet, according to ACMA).

Something that’s also worth talking about is that with the surge of cases that will be reported (supposedly) due to the new reporting channels in place, how will support mechanisms cope? This most obviously points to hospitals and their ICU wards, but what about GPs — and for those who don’t have GPs, what about COVID-19 hotlines which are already filled to the brim with people who are alone in isolation, with no one to reassure them of what is going on or what to do? There are significant flow-on consequences of the policy responses we have seen in recent days, and as per usual, these impacts will be felt hardest by those in marginalised communities.

Thanks so much for taking the time to read this all — please let me know of your thoughts below, and as always, please follow the most recent health advice and stay safe.

Sepehr