‘It’s the math, stupid’: Why we may be reading the Covid-19 numbers all wrong – Pakistan

Over the past three months, the world has watched in disbelief as health authorities have announced a number of new patients affected by the new coronavirus.

One day, the special assistant to the Prime Minister of Health, Dr. Zafar Mirza, warns the nation that the death rate could increase if preventive measures are not taken.

Then there is the Prime Minister of Sindh, who fears that an increase in locally transmitted cases is a bad omen.

So what do these numbers mean?

Here, we break down for you what each of these numbers entails and why you should worry about any or all of them.

Confirmed cases

The number of people affected by the new coronavirus, which causes a disease called Covid-19, has increased more than 1.8 million worldwide, as of April 12.

But as with all data, this number should also be read with a pinch of salt. As far as we know, this could be only a fraction of people infected with the virus.

There are multiple reasons for this:

• In Pakistan, for example, patients are less willing to come forward due to stigma or fear of being quarantined.
• Not enough tests
• Deliberate under-reporting by governments
• Efficacy and precision of tests that are carried out leading to false negatives.
• False positives (rare but certainly a possibility)

Suspicious cases

One of the biggest obstacles in the global response to the Covid-19 pandemic is that very little is known about the virus that causes it. In the past three months, scientists from around the world have gathered their ideas to solve the puzzle.

And yet, almost every day a new notice is issued based on new evidence from groundbreaking research.

While the scientific community struggles to find an anecdote, governments have been struggling to gather the necessary resources to control the spread of the virus.

What we do know is that the virus causes specific symptoms when it affects the human body. What we also know is that it affects the elderly and the immunosuppressed more than others. This is how authorities can monitor suspected cases.

In Pakistan, for example, you will only be tested if you have a fever and can prove that you have traveled or met someone who tested positive for the virus.

However, a significant percentage of the population does not show any symptoms of the virus. This is what skews the data.

What's more dangerous is that these asymptomatic patients are indeed carriers and can infect others who may be more vulnerable.

Number of tests

For Nate Silver from Five-Three-Eight, an online publication based in the US. USA Who has a habit of incorporating big data into intelligible stories, this is the most important number to look at.

In his recent report, titled "Coronavirus Case Counting Doesn't Make Sense," Silver argues that if the amount of evidence is not taken into account when analyzing the Covid-19 data, its analysis could be the complete opposite of what which really is true.

And that's where governments need to be careful. In Silver's words: "A country where the number of cases is increasing because you are doing more testing, for example, might actually be controlling your epidemic. Alternatively, in a country where the reported number of new cases is decreasing, the situation could get worse, either because your system is too overwhelmed to perform adequate tests or because the speed of the tests is slowing down for public relations reasons. "

Case fatality rate (CFR)

For many epidemiologists (experts in the medical field dealing with the incidence, distribution, and possible control of disease), this is the number that holds the key to understanding the prevalence and severity of a pandemic.

The fatality rate, according to the Dictionary of Epidemiology, is "the proportion of cases of a specific condition that are fatal within a specified time." In other words, how many of the positive patients eventually die within a specified time.

This is the metric used by epidemiologists to measure the severity of pandemics such as Ebola or even various strains of influenza and to guide responses.

However, in the case of Covid-19, instead of depending on the number of infections or the CFR, researchers are looking at the daily deaths attributed to Covid-19, according to this report in Nature magazine.

Some experts believe that total deaths from the virus over time is a better statistic Compare how much the outbreak has devastated countries instead of looking at total cases. This is because they argue that the total positive cases are strongly correlated with the number of tests performed, which itself varies from place to place depending on the resources and strategies used in the country and because a significant number of infected people are asymptomatic. .

Reproduction ratio or R

In epidemiological models, the "breeding ratio" or R represents the number of people that each infected person infects.

Silver explains it this way: “If a disease has an R of 3, that means that each infected person transmits it to three other people. So an initial case becomes three newly infected people, who become nine people, who become 27 people, who become 81 people, and so on: the very nature of exponential growth is that you get out of control quickly!

The R for Covid-19, established by the WHO from data obtained from the Chinese authorities, was 2.6. That meant that each infected person would infect at least two other people.

That is why social distancing is so important to stop the spread of the coronavirus. In doing so, authorities around the world, including Pakistan, have been trying to keep the R below 1.

Locally transmitted cases

The first case of Covid-19 reported on Pakistani soil was that of a person who had just returned from Iran. Over the next few weeks, as the number of patients increased, almost all had a history of travel.

The government responded by temporarily blocking airports and banning entry for both Pakistani citizens and foreigners.

On April 12, Dr. SAPM Zafar Mirza announced that half of the Covid-19 cases in the country are now transmitted locally.

This is truly concerning, as it denotes that the virus has now taken hold in our communities and is spreading among the local population.

So what number?

The Covid-19 epidemic is likely to be studied by epidemiologists and other researchers in the coming years. Much will be said about the global response and much more about the lack of it.

At this time, however, when we look at these numbers, it is important to remember that they may not be telling the whole picture. In some cases, it may be necessary to look at a combination of these statistics to develop a better picture of the situation on the ground.

That said, context is key when analyzing the Covid-19 data, and if health experts can read these numbers with a holistic approach, it should give you a fair idea of ​​the virus's trajectory in the region and guide your response.