With influenza A, it takes almost three years to know its real impact: why it is so difficult to obtain data in the middle of an epidemic

The feeling of not really knowing what is happening is something that has been flying for days (if not weeks) over the COVID-19 crisis. Yes, the official data on the coronavirus are erroneous, provisional and mediated. Much of this is held by many of the authorities around the world who refuse to be clear on how contagions, hospitalized and deceased people are computed, on how many people have actually been tested or on the exact demographics and dynamics of the outbreaks.

In part, but only in part. The harsh reality is that measuring in the middle of an emergency is complicated and, while demanding transparency, we must keep our expectations of clear, precise and verifiable information at bay. It is enough to think about the last great respiratory infectious disease that strained the world, Influenza A, and how the real data of its impact was not known until almost three years later to make a mental idea of ​​the problem we are facing.

A morass of erroneous data

Martin Sanchez

For the past few months, the debate over the pandemic numbers has been a constant. First, about the number of cases in each country. Something that led to a very intense public discussion about what was considered a 'coronavirus infected' in different countries of the world and how methodological differences could have a very radical impact on the total figures.

Added to this debate was the issue of the tests actually carried out. Something that started to emerge very quickly is that the different countries had been following very different diagnostic approaches from each other. Some countries, such as South Korea, had opted for the intensive use of all kinds of tests in the general population; other states, however, had chosen to limit the tests to hospitalized or very ill patients.

It seemed evident that the number of tests was a key variable that influenced the number of cases detected in each country. However, we quickly realized that these differences were not easily 'normalizable'. In other words, not even taking into account the protocols of each of the national health authorities were easily comparable data sets.

That is why, a few weeks ago, public opinion turned on what seemed, at that time, the most reliable figure: the number of deaths. Common sense indicated that the death rate was difficult to see altered by the particularities of each country. However, we quickly learned that this was not true. Doubts about the Chinese data or uncertainties about whether all the deaths directly related to the virus were actually being counted (or only a small part of them) made comparative discussions a high-risk exercise.

In the last days, as if that were not enough, we have discovered that not only the differences between countries are difficult to sustain. It is that even the data between regions of the same country are not comparable. Perhaps the best example of this is the number of ICU patients in Spain. After days and days in which the Ministry of Health had explained that the numbers of critically ill patients were accumulated data, María José Sierra, one of the spokespersons for the Center for Health Alerts and Emergencies of the Ministry of Health, was forced to admit that, in fact, "it reflects differences between Autonomous Communities. Some are reporting the accumulated number and others the number of patients admitted to the ICU" daily, discounted discharges and deaths.

Between strategy and saturation

Brittani Burns

Why does this happen? In a scenario like the current one, suspicions are the order of the day. There is no shortage of those who remember that the 18 flu was known as 'Spanish' because it was Spain that, oblivious to the Great War, was the only important state that began to publicly report it. There is also no lack of those who see a parallelism between that case and the current one (or between other pre-existing dynamics of international politics).

The truth is that it cannot be denied that some countries (the Chinese opacity, its movements to separate itself from the virus or the doubts about how Japan seems to have approached the crisis discreetly to protect the Olympic Games) have taken measures and positions that have not been they explain (fully) without that geostrategic element.

However, it would be unfair to blame the pandemic data problems only on this alleged geopolitical tension. We must not lose sight of the fact that we are really facing a recent unprecedented crisis. As much as international organizations have been warning for a possible pandemic like the current one for years, the truth is that (in sight it is) that our systems were not prepared.

The saturation of health systems around the world, the reduction to a minimum of the rest of the administrative structure of the states, poor political decisions and the lack of widely accepted common standards when addressing real-time quantification of this type phenomena have played a huge role behind the problems we are talking about.

Without forgetting the complexity

MoMo - April 1

Strategy and inability are two fundamental factors to explain the poor quality data, but we must not forget one more factor: the complexity of measuring such a phenomenon. As I said at the beginning of the article, the last international epidemic of an infectious respiratory disease was Influenza A. In that case, it took almost three years to refine and analyze all the data to be able to draw the real impact of the epidemic.

The reason is easily explained. Circumscribing ourselves to the Spanish case, the most updated mortality information system is the MoMo for daily mortality surveillance. These reports synthesize daily mortality from all causes, extracting it from the 3,929 computerized civil registries in the country and comparing it with estimates (based on historical mortality means according to a series dating back to 2008).

The MoMo is the most "real-time" system, but it has numerous problems from notification systems (to the point that the system keeps updating the figures every day for the next 28 days) or the fact that it only represents 92% of the Spanish population. To find reliable data we have to wait almost a year after the end of the year we want to study. During that time, the National Institute of Statistics collects all the data, normalizes it and unifies it.

That, under normal conditions. Today, the MoMo already details in its reports that the delays in the notification of deaths have lengthened and it is not unreasonable to accept that this delay profoundly distorts the usefulness of the data from the surveillance system.

To these logistical problems, we have to incorporate the methodological ones. It is important to remember that, presumably, the death data provided every day by the Ministry only collects a very small part of the real impact of the virus on the country's mortality. This is something that epidemiologists know very well. In fact, the deaths caused annually by the flu are not evaluated in this way (using the official causes of death of the Registries), but with complex models that allow us to get a precise idea of ​​the impact of the epidemic.

In the case of influenza, as the CAES has explained on several occasions, the difference between one data and another is of order of magnitude: those around 1,000 deaths per year that are registered by one method become more than 10,000 by the more precise estimation system (and commonly used). To this we must add the cases that, under normal conditions, would have been treated more successfully, but which, due to the severity of the epidemic, led to problems.

When will we know what is going on?

Mick Haupt

That is surely the question that many of us ask ourselves. It is foreseeable that the size of the crisis will lead to increased efforts to know, as soon as possible, the figures of the pandemic. However, from what we have explained, although it is expected that analyzes will emerge in the coming months, it is not reasonable to expect that these estimates are as accurate as we would like.

If we finally manage to drown the epidemic before summer, we may begin to have the precise figures (although provisional) in the first months of 2021. Of course, we are talking about the best scenario. Although no one disputes that we are dealing with a historical phenomenon, the truth is that many doubts remain in the air to be able to answer the question that gives the title to this section. What is clear is that, in view of the enormous challenges that await us, it will not be soon.

Image | Giacomo Carra

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