The Mexican Health Ministry said that it started the research on the incident, saying that Perez had been diagnosed with encephalomyelitis (inflammation of the brain and spinal cord). Before the inoculation, Perez experienced an allergic reaction to antibiotics called trimethoprim and sulfamethoxazole that can cause similar severe adverse reactions.
"We are not insisting that it was caused by the vaccine. However, it is necessary to clarify whether it is connected to the inoculation with the vaccine. We are not arguing that it was the reason. There should be a research to confirm it", Palestino said.
Perez's brother-in-law stressed that the doctor's relatives had decided to draw the attention of the media to the incident not to discourage people from vaccination, but to make sure that Perez would be cured adequately and this case would be studied to prevent further incidents.
"The main goal is to care for the health of my sister-in-law, to make sure that she will have no complications. Since it is a new case, no one is able to determine its nature. That is why it is necessary to disseminate [information]", Palestino said, adding that Perez's relatives did not support "the anti-vaccination movement" and did not have "any political or economic interest" in boosting publicity around the case.
On 30 December Perez was paralysed several hours after being inoculated with the COVID-19 vaccine developed by US-based Pfizer and German BioNTech pharmaceutical companies.
Earlier that month, the US Centres for Disease Control and Prevention reported on four cases of partial facial paralysis experienced by the recipients of the Pfizer vaccine.