The general state of Mexico and its population
In attempting to understand the scope of COVID-19 infections in Mexico, we found that the especially susceptible population (aged >60 years) in Mexico represented approximately 12.5% of the population (approximately 15.4 million people), of which at least 69.4% had some type of disability, according to data reported by the National Institute of Statistics and Geography (INEGI) . In our study, 729 participants (approximately 18.2%) were in the susceptible age group. By August 2020, of the almost 57,000 registered deaths due to COVID-19 in Mexico, 58% of cases were adults aged >60 years . According to the Korea Centers for Disease Control and Prevention, the overall case fatality rate (CFR) in Korea was 2.37% in 11,344 patients with confirmed cases of COVID-19 infection as of May 28, 2020, but it was much higher in the elderly (10.9% in patients aged 70–79 years and 26.6% in patients aged >80 years) . For 44,672 diagnosed cases of COVID-19 as of February 11, 2020, the overall CFR was 2.3% in China. However, the CFR was 8.0% in patients aged 70–79 and 14.8% in patients aged >80 years . Thus, older adults are advised to stay home while maintaining social distancing measures to prevent COVID-19 infection.
Another factor that makes the Mexican population highly vulnerable to COVID-19 infection is the high incidence of chronic diseases and metabolic disorders, which is caused by a poor health-care culture comprising an inadequate routine of aerobic exercises, poor diet with limited nutritional content, and high caloric intake and null culture of preventive medicine. Up to 47.40% of patients with COVID-19 were reported to have at least one comorbidity, with hypertension being the most frequent comorbidity (20.12%). The comorbidities that most increased the risk of intensive care unit stay and intubation were diabetes, immunosuppression, and obesity . In this study, 1803 participants (almost 43.89%) had at least one comorbidity. The Centers for Disease Control and Prevention reported that Mexicans are more likely to have type 2 diabetes (17%) than non-Hispanic whites (8%) . In this study, 165 participants (4.12%) had diabetes. Moreover, INEGI reported that 8,600,000 people in Mexico had diabetes mellitus in 2018 . Diabetes is a factor used to assess the severity of COVID-19 cases. In a Mexican study, of approximately 373,963 adults with COVID-19, 16.1% had diabetes. The predicted probability of hospitalization was 38.4% (37.6–39.2) for patients with diabetes only and 42.9% (42.2–43.7) for those with diabetes and one or more comorbidities . Regarding arterial hypertension in Mexico, according to the National Health and Nutrition Survey of Medio Camino 2016, carried out by the National Institute of Public Health (INSP) and the Ministry of Health, one in four adults in Mexico had arterial hypertension. Approximately 40% of these patients were unaware they had this condition, which affected their health, and of the approximately 60% of patients who knew about the diagnosis, the condition was controlled in only half of the patients . In this study, 330 participants were diagnosed with arterial hypertension.
Moreover, the SARS-CoV-2 virus uses receptors on the cells in the lungs to cause infection, regulating blood pressure as direct routes to infect cells, using angiotensin-converting enzyme 2 (ACE2). Patients with hypertension can have changes in ACE2, either in its structure or expression level, which makes it easier for the virus to cause a more severe infection. ACE2 levels may be increased in patients with cardiovascular disease. The available data associate baseline comorbidities with a severe course of COVID-19 , and interrupting anti-hypertensive treatment can precipitate cardiovascular decompensation .
Regarding obesity and overweight, INEGI in 2018 reported that the age group that reports the highest prevalence of obesity is the age group of 30–59 years, and 35% of men and 46% of women have obesity. Regarding the prevalence of obesity, a high prevalence is observed for the population aged 12–19 years (17%) and >20 years (42%) in the northern region of Mexico . In this study, 1272 participants (31.76%) had a diagnosis of obesity. A previous study showed that obesity is a risk factor for hospitalization, admission to the intensive care unit, and the development of severe consequences that lead to death in cases of COVID-19 . A French study showed that severely obese patients (body mass index >35) require invasive mechanical ventilation more frequently than lean patients, regardless of age, sex, diabetes, and high blood pressure . Considering the Mexican population's health condition, it is easy to understand why the COVID-19 fatality rate reached such high levels and why the prevention policies were directed toward isolating the population at risk, representing a large percentage of the Mexican population.
Many other factors contribute to Mexico's pandemic situation, including some difficult to control, such as weather and air pollution. A Mexican study reported that in Mexico, climatic conditions played a crucial role in local infection during phase 1 of the COVID-19 pandemic making temperate regions, such as Michoacán, Jalisco, and Puebla, more vulnerable than dry regions, such as Chihuahua, Durango, and Zacatecas, or tropical regions, such as Colima, Campeche, and Morelos . Another Mexican study attempted to determine the relationship between air pollution in Mexico City and severe COVID-19 cases. It concluded that for Mexico City, there was evidence of a positive relationship between pollution and mortality, which increased significantly with age and appeared to be driven mainly by long-term exposure rather than short-term exposure to pollution . Nevertheless, probably the most critical factors to influence the COVID-19 pandemic's development in Mexico are the status of the health-care system and government strategies. Accordingly, a study published in December 2020 strongly criticized Mexico's position on the pandemic. It stated that Mexico's vast inequality, underfunded health-care system, sizeable informal economy, and belts of cramped, multigenerational housing made it particularly vulnerable to the spread of the virus. However, a lack of strategy, combined with the president's mixed messages, has exacerbated the situation in a poorly equipped country to handle a pandemic .
Regarding this lack of a sound health-care system, we asked the participants about their confidence in the Mexican health-care system; almost 40% of the participants disapproved of the system. The reasons why they thought that hospitals were not prepared for the pandemic were: "The facilities and equipment required to deal with the pandemic situation are not available" (according to 65% of participants), "Health-care personnel do not have enough supplies" (59% of participants), and "There are not enough health-care personnel to serve the entire population" (43% of participants). This finding indicated that almost half of our study participants considered the Mexican health-care system as inferior and believed that a lack of support to the institutions to enable doctors, who were already overwhelmed in every way, to perform their work was a problem. Moreover, because of these issues, Mexico is the first country to report deaths of health-care personnel due to COVID-19 . Nevertheless, it is a reality that the doctors themselves are often not in ideal health , and they are a reflection of all the problems and health conditions that we discussed earlier. Taken together, all the problems discussed in this section represent the general overview and conditions due to which Mexico has experienced high incidences of COVID-19 infection and deaths. However, this does not explain the rapid spread of the virus due to the general Mexican population's attitude toward the pandemic and its preventive measures.
The attitude of the Mexican population toward the pandemic and their preventive measures
In this social media era, knowledge and information are now easier to obtain, even more so during a global crisis, such as the COVID-19 pandemic. The Internet, scientific journals, and the news overexpose people to all kinds of information about the virus, while scientists continue to evaluate new data and make novel discoveries about the virus. The mechanism underlying social media's effects on behavioral changes is that the coverage of a pandemic on social media can magnify the public's fear and urge the public to take preventive actions . However, the participants in our study did not appear interested in information about SARS-CoV-2: e.g., only 59% stated that they were continuously looking for information regarding the progress of the pandemic, and 16% stated that they preferred to avoid information regarding COVID-19. On actively tracking COVID-19 updates, our findings are not that far off from those of a German study, in which 67.1% of participants indicated that they had been following media coverage about the COVID-19 outbreak for >1 month . However, in contrast to our findings, only 2.7% of participants in that study (almost eight times less than in our study) did not follow news about COVID-19. Leaving aside disinterest, at least the main message in the Mexican health-care campaign appears to be getting through to the population because almost 99% of our participants mentioned knowing about the symptoms of COVID-19, and almost 90% of participants stated that they were aware of where they could go in case of having current symptoms.
To understand the degree and speed of the spread of the virus in Mexico, it is essential to investigate how Mexicans relate to each other, protect themselves with preventive health-care measures, and follow government instructions. Undoubtedly, one of the factors that contain the virus in developing countries rather tricky is overcrowding in these countries. In our study, 3091 participants (almost 77.19%) lived with >3 cohabitants, of which at least 87.4% had one household member who frequently broke social isolation. Even when the participants were constantly exposed to not quarantined people, almost three out of four stated that they were maintaining adequate social distancing measures. However, almost 60% of participants stated that they knew at least six individuals who were not following proper quarantine measures. This finding indicated that it was easier for people to judge others regarding their social distancing measures. Regarding the effectiveness of being quarantined, a study conducted in China concluded that latent individuals' contact rate is between 6 and 18, representing the possible impact of isolation and quarantine measures on the disease infection rate. These findings suggest that interventions, such as isolation and quarantine, can effectively reduce the peak number of COVID‐19 infection cases and delay infection cases' peak time by reducing the contact rate . Another study showed that the infection's epidemic trend mainly depends on quarantine and suspected cases . Worldwide, it appeared easier to stay in social isolation during the early stage of COVID-19 spread. During the initial months of the quarantine, a study conducted in China reported that the public displayed significantly strong support toward quarantine measures throughout the outbreak period, except for locking people up and using imprisonment or other legal sanctions against those who failed to comply with the stringent regulations . However, over the months of 2020, maintaining strict isolation and avoiding large gatherings and events was increasingly complex, and people were more reluctant to follow social distancing measures. The reasons why people no longer wanted to comply with government instructions to maintain social distancing were the need to keep their lives afloat and the ill effects of social distancing. The quarantine has resulted in lifestyle changes such as reduced physical activity and unhealthy diets . Our study participants could not perform strict social distancing measures presented in Table 2 and include the need to keep their jobs, maintain their daily routine, and help family members. However, it again appears more straightforward for people to judge others because when asked about the reasons why they believed that others did not follow the quarantine measures, the most frequent response was related to work, but reasons such as disinterest, despair, and the desire for recreation were also common. Throughout the quarantine in Mexico, different regions have allowed the opening of bars, restaurants, and nightclubs, except for weekends, and even significant events, leaving the general population to decide whether to assist with health measures . These types of measures have been taken by almost every country in the world. One of the main challenges that governments face in a pandemic, such as the COVID-19 pandemic, is ensuring good public health while reducing the adverse economic effects of measures such as country-wide lockdowns. There is an implicit trade-off between economic wealth and COVID-19 cases and deaths . This is a key factor in the snowballing of cases, which prevents the pandemic from coming under control.
In a country where general conditions make a prolonged quarantine unrealistic, the use of preventive measures against the virus becomes a mainstay to control its spread. We asked our study participants how often they used preventive measures against COVID-19, and they responded with a high level of use. However, 70% of participants also answered that <50% of their cohabitants used such measures. Some reports on global behavior regarding the use of face masks stated that Mexico is one of the countries with the maximum use of masks [35, 36]. This fact was also announced by the Mexican government , and it is in agreement with our findings that approximately 99.5% of the studied population used face masks. However, in our study, only fifty percent used a certified mask, and the remainder used a homemade or handmade mask that did not meet quality standards and did not confer or guarantee any protection to the user or people around. This means that only one in two Mexicans uses the WHO's primary protection tool against the coronavirus . The use of face masks is supported by science because coronavirus transmission is mainly through aerosol drops exhaled from infected patients, whether symptomatic or not. A Chinese study regarding face mask use concluded that it is reasonable to suggest that face masks can mitigate the current pandemic because they may reduce coronavirus particles in aerosols and respiratory droplets . That is why using measures that protect from aerosols and droplets is also important, such as protective glasses and other equipment. However, the low degree of acceptance of eye protection in our population was alarming. The reasons why our study population did not use the different types of preventive measures against COVID-19 are presented in Tables 3 and 4, and they indicate an economic, social, and educational reality that must be fought with information and health education; otherwise, it will be impossible to stop the COVID-19 contagion.
The WHO has strongly emphasized the importance of carrying out tests to detect cases timely, predominantly asymptomatic cases, and isolate them . However, in developing countries such as Mexico, screening campaigns are limited, and thus it is decided to opt for different models. For example, a model designed at the University of Guadalajara, Mexico, has been used in Jalisco, Mexico, and it detects 100% of suspected cases with mild symptoms, unlike the Sentinel model proposed by the federal government, which randomly samples one out of 10 suspected patients and does not have a specific screening method in COVID-19 concentrated areas. . Even with these predictive epidemiology models, the lack of a massive rapid and reliable testing campaign leads to difficulty in containing the pandemic because many cases are not being treated or counted. When comparing the number of COVID-19 tests made by country between Latin American countries performed in January 2021, Mexico was ranked 7th, whereas Brazil, Peru, and Colombia were the top-ranked countries . In a world ranking evaluated in December 2020 of tests per million inhabitants, Mexico was ranked 24, in a ranking led by the United Kingdom, the United States, and Russia . A total of 3502 participants (approximately 87.46%) in our study had never undergone COVID-19 testing, but 2880 participants (71.92%) reported knowing at least one person who had been diagnosed with COVID-19. The lack of tests, together with the people's limited participation to undergo testing, makes the accurate epidemiological tracking of COVID-19 cases and obtaining an adequate count of actual cases rather difficult.
In summary, we found that most participants of our study lived with more than three cohabitants, of which at least one constantly broke social isolation, used noncertified face masks with limited effectiveness, and poorly used other preventive measures against coronavirus. We also found inadequate epidemiological monitoring with evidence in the case of our study population. Taken together, this indicates a complicated COVID-19 situation for Mexico.