Patient One: Investigation During the Pandemic

April 27, 2020
Laboratories around the world are uniting forces in order to find vaccines and medications against the coronavirus. Meanwhile, an essential investigative task is identifying patient one in order to prevent future outbreaks.

The coronavirus (COVID-19) has expanded non-stop all over the globe and has been monopolizing means of communication and the attention of our governments. Just the same, amidst all the commotion, there’s a factor that we tend to overlooks: the importance of finding patient zero in a pandemic.

There’s something we’ve all been hearing, though distantly, from the beginning of this global pandemic. The focus has been on the seafood market in the city of Hubei, China. After that, the lines of investigation blur.

Was it the bat of the pangolin that first passed the virus onto humans? Who exactly was the first person to become infected?

All is this may seem like a redundant point. Why spend so many resources looking into something that already happened?

The answer is simple but straight forward: Knowledge of how the pandemic started will prevent situations like this one from repeating.

Keep reading if you want to know more about patient zero when it comes to coronavirus.

Index cases

Patient zero, or the index case, refers to the first case that triggers the attention of the investigator and sets of a series of actions, visits, and steps that are necessary to discover the cause of infection.

In the first stage of this process, there are three types of index cases:

  • The primary case: The first case to occur in chronological order.
  • The co-primary case: This is the following case after the primary and included within a maximum period of incubation coming from a common source.
  • The secondary case: This refers to the case that comes after the primary that, given the incubation period, can be attributed to transmission from the primary case.  In other words, it’s a person who gets a disease from exposure to a primary case.

This terminology may sound a bit strange and difficult to understand, but one thing should remain clear: The index case can be any of the three. What’s important with patient zero isn’t so much whether it was the first or second case of infection. Rather, the importance lies in warning health authorities and initiating research mechanisms.

We’ll never know for sure who the first person was to be infected by an illness like COVID-19. In many cases, s/he may have been asymptomatic. This is because attention was placed on the case or cases that first set off alarms.

Finding patient zero of the coronavirus pandemic.

We’ll never know for sure who the first person was to contract an illness like COVID-19. But researchers do need to find out as much as they can. 

Discover more: Coronavirus Detection: What’s a PCR Test?

Patient zero: The index case in China

This news is surprising: The first reported case of coronavirus seems to have taken place on November 17, 2019, according to Chinese authorities. Experts believe it was a 55-year old resident of the city of Hubei.

Clearly, experts arrive at these conclusions by performing tests of the illness a posteriori. This is because when a patient displays a clinical picture but the illness has yet to be identified, doctors attribute the symptoms to other causes.

  • Near the end of March of this year, experts believed that the pangolin was the possible focus of infection. What’s more, recent studies provide further substantiation for this theory.

In the scientific journal Nature, a research team published the results of the analysis of different remains of frozen pangolin. The data is revealing since researchers found two strains of coronavirus with 90% similarity with the virus currently affecting humans in 5 of the 18 samples. This implies that it’s more than likely that a mutation of the virus from the pangolin may have adapted to invade humans.

So, if we have the more than likely vector of the illness and the first patient to display a clinical picture, then what’s missing?

The index case of COVID-19.
Although various investigations are still underway, findings suggest that there may have been a mutation of the pangolin coronavirus that allowed is to adapt in order to invade the human body.

Don’t miss out: “Flattening the Curve”: Epidemiological Implications

Knowledge allows for action

There isn’t just one patient zero. In fact, it depends on the geographical region. It’s vitally important to discover the origin of the main source, but also the rest of the world as well. 

In Europe, a 33-year old German may have been the first European patient to contract the virus, according to a publication in the New England Journal of Medicine (NEJM). This leads us to several questions:

  • How did the patient contract the illness?
  • What means of transportation did the patient use to move about during the contagion period?
  • How many people did the patient interact with during the incubation period?

The questions, and an intimate number more, are what experts want to answer by looking for the index case. If we know the dynamics of the global pandemic, then the next won’t be such a surprise to government entities.

For example, if researchers discover that 90% of the index patients from each country contracted the illness a result of a plane ride, then the next outbreaks will be easier to control.

Basic knowledge about an event is the key to prevention. Therefore, despite studying the measures for preventing the propagation of the pandemic, knowing how it began is also vital.

  • Yuen KS, Ye ZW, Fung SY, Chan CP, Jin DY. SARS-CoV-2 and COVID-19: The most important research questions. Cell Biosci. 2020;10:40. Published 2020 Mar 16. doi:10.1186/s13578-020-00404-4
  • Carinci, F. (2020, February 28). Covid-19: Preparedness, decentralisation, and the hunt for patient zero. The BMJ. BMJ Publishing Group. https://doi.org/10.1136/bmj.m799
  • Lam, T. T.-Y., Shum, M. H.-H., Zhu, H.-C., Tong, Y.-G., Ni, X.-B., Liao, Y.-S., … Guan, Y. (2020). Identifying SARS-CoV-2 related coronaviruses in Malayan pangolins. Nature. https://doi.org/10.1038/s41586-020-2169-0
  • Xiao, K., Zhai, J., Feng, Y., Zhou, N., Zhang, X., Zou, J.-J., … Shen, Y. (2020). Isolation and Characterization of 2019-nCoV-like Coronavirus from Malayan Pangolins. BioRxiv, 2020.02.17.951335. https://doi.org/10.1101/2020.02.17.951335
  • Rothe, C., Schunk, M., Sothmann, P., Bretzel, G., Froeschl, G., Wallrauch, C., … Hoelscher, M. (2020, March 5). Transmission of 2019-NCOV infection from an asymptomatic contact in Germany. New England Journal of Medicine. Massachussetts Medical Society. https://doi.org/10.1056/NEJMc2001468