The so-called serological tests are used to detect the presence of antibodies that defend you from SARS-CoV-2, and confirm that you have been exposed to the virus. The performance of these tests is based on the antigen-antibody affinity.

An antigen is a foreign substance that makes our immune system react. An antigen is a provocateur, and the human immune system is one of those guys that jump fast in the face of external provocation. It is warm-blooded, never better said. The responses of our immune system can be specific and quite effective. In the presence of an antigen, our adaptive immune system is capable of producing antibodies that specifically bind that antigen to inactivate it. These antibodies are immunoglobulins M (IgM) and G (IgG). Circulating in the blood, the IgMs appear first and then the IgGs.

One of the greatest antigens of world football history has been the Italian defender Marco Materazzi. In 2006, Marco —who was an Inter Milan player for 10 consecutive years— made a strong impression on Zlatan Ibrahimovic —then a Juventus player— that caused him an injury. Zlatan’s immunological response took four years to become effective. Playing for Milan, Zlatan waited for the moment to meet Materazzi on the pitch and then launched a taekwondo kick to send him to the hospital. The hospital thing is not hyperbole. Materazzi left San Siro by ambulance.

Materazzi’s antigenic activity did not stop there, and in the extra-time of the 2006 World Cup final, it caused an immediate immunological reaction from Zinédine Zidane, who head-butted him in the chest when Antigen Materazzi, a few minutes from the penalty shootout, took an inappropriate interest in Zidane’s sister. This headbutt has been immortalized in a five-metre bronze sculpture, which came to be exhibited at the Pompidou in Paris. After being shown at numerous places, today you can find it at the Museum of Modern Art in Doha (Qatar).

In short, Materazzi was an antigen (protein of the SARS-CoV-2 virus) that caused the appearance of two antibodies to suit it. These antibodies normally appear two to three weeks after infection and are of two types: IgM *, which last four or five weeks, and IgG * that stay with us for at least one or two years. It could be said that Zidane was an IgM antibody because he acted fast and that Ibrahimovic was an IgG because he stored the memory to attack Materazzi later.

Note: In June I heard about IgA, which is an antibody secreted in mucosa such as saliva, and which is also produced after exposure to SARS-CoV-2. IgAs appear early, like IgMs, before IgGs ⁷. So I looked for some other antigenic effect from Materazzi, and found an assault by him on Siena player Bruno Cirillo in 2004, in the San Siro locker room, which resulted in an eight-match ban for Materazzi as immunological reaction.

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