**Abstract**

In this chapter, we discuss general information about the post-COVID-19 condition, also known as long COVID. Since it is still under research, many questions remain unanswered. Nevertheless, post-acute complications due to infections have been previously reported for other viruses. Among those complications that remain are anosmia, fatigue, cardiovascular, and pulmonary. The evidence so far suggests that these complications decrease with time. The most worrying persistent symptoms due to COVID-19 are related to neurological damage. Most post-COVID-19 complications can be treated in a standard way, but their impact on life quality is unknown. Finally, we present a rough landscape of long COVID-19 in Mexico and Latin America. More studies are needed to study this condition and its impact on public health.

**Keywords:** long COVID-19, post-acute COVID-19, persistent symptoms, fatigue, brain fog

## **1. Introduction**

In December 2019, an outbreak of pneumonia of unknown origin occurred in the City of Wuhan, China [1]. On January 9th, 2020, the virus behind the infections was identified as a new strain of β-coronavirus [2]. Subsequently, on February 11th, it was named by the World Health Organization (WHO) as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the associated disease was coronavirus disease 2019 (COVID-19) [2].

According to an interim WHO guidance for the management of patients with suspected COVID-19 [3], early reports from the China Center Disease Control (CCDC) suggested that most people who developed a confirmed case of COVID-19 infection manifested mild symptoms, 14% developed a severe disease that required hospitalization, of which 5% required admission to the intensive care unit; with a higher risk of death those with advanced age and presence of comorbidities [3].

Severe disease and death have been observed in patients older than 75 years. The comorbidities associated with a higher risk of death are hypertension, cardiovascular diseases, diabetes, chronic respiratory diseases, and cancer [4].

The COVID-19 symptoms related to neurological disease reported so far are anosmia, dysgeusia, muscle pain, and headache during the early stage of the infection [5]. These symptoms suggest many hypotheses about how the virus reaches the nervous system. Some of them are its potential entry via the olfactory groove or bloodstream [6–9].

In Mexico, the first official case was reported on February 28th, 2020 [10], and by March 11th, 2020, the WHO declared COVID-19 a global pandemic [11]. Up to May 5th, 2020, 3,525,116 confirmed cases were reported globally, having a case fatality rate of 3.4% [2].

In Mexico, up to January 26th, 2022, the national cumulative incidence rate was 36.00 cases per 1000 inhabitants. Meanwhile, the number of cases was 13,682,501. The mortality rate per 1000 inhabitants in age groups older than 60 was 12.04 [12].

According to Wang et al. [13], the estimated excess mortality in 2020–2021 was 18.2 million people. Mexico has not been the exception since, according to the same study, it is among the countries with the highest excess mortality induced by COVID-19, accounting for 798,000. According to Halabe-Cherem et al. [14], the impact of COVID-19 on health extends beyond disease and mortality rates, affecting the management of chronic conditions, preventive care, and vaccination programs. Moreover, many patients experience physical and mental sequelae that persist for months after recovery from the virus. This persistence of symptoms is known as "prolonged COVID" or "post-COVID syndrome" [14].
