Coronavirus disease 2019 (COVID-19) is an infectious pathology caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). On 12 December 2019, the first case was detected in Wuhan, China, ¹ and the disease spread so rapidly globally that on 11 March 2020, the World Health Organization (WHO) declared it a pandemic. ² This pandemic has changed the lives of millions of people and has 6.3 million deaths around the world. ³

Governments applied various public policies to reduce its spread, one of them being social isolation. This measure was applied in several countries around the world, Peru being one of them and probably with the longest duration. ⁴

Trials to test the efficacy of the vaccine were reported at the end of 2020, and vaccination officially began around that time in several countries. ⁵ Vaccination in Peru began on 9 February 2021 and continues in various age groups around the country. ⁶ Currently, 72% of the population is of Metropolitan Lima immunized with two doses of the vaccine 73.92% have received the third dose and 25% have received the fourth dose. ⁷

The conditions of social confinement have had an impact on people's health, including a decrease in physical activity levels and an increase in sedentary behavior. ⁸ According to a study in Chile, the increase in physical inactivity could have important metabolic implications for the health of the population. ⁹

On the other hand, the emergence of pandemic-related psychological reactions; cases in people without a pre-existing mental health problem have increased and pre-existing cases were accentuated by confinement. ¹⁰ A study in China reported moderate to severe levels of stress in the population. The most emotionally affected age group according to this study was young people aged 18-30 years. ¹¹

The human response to a pandemic is not uniform and may vary between countries and regions. Likewise, given that lethality differs by gender and age, it is possible that coping may also differ. Subjects with co-morbidities, males and older people have had higher case fatality rates. ^{12 , 13} Peru is one of the countries with the highest case fatality and currently has COVID-19 mortality of 202, 424 people. ¹⁴

In Lima, a study by the Consortium of Universities revealed that the mental health of students has deteriorated due to the situation of confinement. Academic factors had a greater impact on mental health, which may lead to a decrease in their performance. Higher levels of anxiety, depression, and stress symptoms were also found. Other factors such as fear of contagion, hours of sleep, and demographic conditions were also assessed as influencing mental health; however, they did not present statistical results that allow further analysis. ¹⁵

It is therefore important to have instruments that allow us to assess health-related quality of life (HRQoL) in pandemic circumstances. For this purpose, there are several HRQoL questionnaires, ^{16 – 18} which have been successfully applied in different parts of the world in situations other than the COVID-19 pandemic, and which can be applied to the general population or certain pathologies. They can be used to monitor both diseases ^{19 , 20} and interventions. ²¹ It would therefore be of utmost importance to use an instrument that assesses HRQOL and to be able to compare it in subjects who have suffered from COVID-19 with those who have not.

The best known and most validated HRQoL questionnaire for the Spanish-speaking population is the “short form-36” (SF-36). The SF-36, which contains 36 questions, assesses the personal perception of each individual's health in three components: physical, mental and general health component. Its application has been optimal in different age groups. ²² This instrument, developed in the United States, has subsequently been translated and applied in Spain. ²³

In Peru, a variant of this HRQoL questionnaire called SF-20, containing 20 questions, has been validated for both sea level and high-altitude populations. ^{21 , 24} Other groups have further reduced the questionnaire and developed the SF-12. ²⁵

Based on the inclusion criteria, data from 638 study participants (256 men, and 382 women) were analyzed. ⁵⁰

The characteristics of the population are shown in Table 1. In total, 40% of participants were men and the remaining 60% were women. Of the study population 56.9% (95% CI 52-59.9%) resided in Lima downtown, 20.60% (17.4-23.8%) in eastern Lima, 14.1% (11.3-16.8%) in northern Lima, and 3.3% (1.9-4.7%) in western Lima.

In total, 85.9% (95% CI 83.2-88.6%) of respondents performed compulsory social isolation. Quarantine, for cases where COVID-19 was detected, was performed by 96.9% (95% CI 92.1-99.1%) of those diagnosed with the disease. In the case of vaccines, 77.1% (95% CI 73.9-80.4%) of the study population had completed both doses of the vaccine.

Overall, 19.5% of male respondents studied had COVID-19 while 20.4% of women had COVID-19 (p>0.05). No significant differences were found in anthropometric measurements between the groups with or without COVID-19. No significant difference was found concerning the final HRQoL score or any of its components in people with COVID-19 compared to people without COVID-19 (p>0.05).

Age correlated with BMI, waist circumference (WC), neck circumference (NC), HRQoL - mental component (MC) and time after vaccination (TAV); BMI with WC, NC, HRQoL - general health (GH), and time post-vaccination; WC correlated with NC, general health, and TAV ( Figure 1).

The results related to COVID-19 are presented in Table 2. Among subjects who had COVID-19 82.4% performed compulsory social isolation while in those who did not have COVID-19 86.3% performed compulsory social isolation (p>0.05). Of the subjects who had COVID-19, 96.9% (95% CI 92.1-99.1%) reported having quarantined themselves after diagnosis of the disease.

Of the total subjects diagnosed with COVID-19, only 87.5% (95% CI 80.5-92.7%) had disease symptomatology. Of the subjects who were not diagnosed with COVID-19, 15.9% (95% CI 12.8-19.3%) reported having COVID-19 symptoms. The initial symptoms of COVID-19 infection are fever, headache, cough tiredness, absence of smell and taste; if they aggravate the disease, shortness of breath manifests. ²⁸

Regarding weight gain, 58.6% of COVID-19 subjects and 56.3% of non-COVID-19 subjects felt that they had gained weight from COVID-19 (p>0.05 between groups). Similarly, 68.85% of subjects with COVID-19 and 67.5% of subjects without COVID-19 felt that they had decreased physical activity during compulsory social isolation (p>0.05 between groups). The presence of anxiety or depression during compulsory social isolation was observed in more than half of the subjects evaluated, with no difference between the groups with or without COVID-19 (p>0.05) ( Table 2).

Of the population studied, 3.9% of subjects with COVID-19 and 4.3% of subjects without COVID-19 reported having participated in a clinical trial of the COVID-19 vaccine (p>0.05 between groups) ( Table 2).

Table 3 presents the results of the multivariate analysis to associate the HRQoL questionnaire total score controlling for the variables BMI, sex, age in years, whether or not hospitalized for COVID-19, time in compulsory social confinement, and history of chronic disease.

In the crude model, obesity, female sex, time in compulsory social confinement, and the presence of chronic disease are associated with lower total scores on the HRQoL questionnaire. These same variables remain significantly associated in the adjusted model.

Table 4 presents the results of the multivariate analysis to associate the physical component of the HRQoL questionnaire. Obesity, female sex, older age, hospitalization in ICU, longer time in compulsory social confinement, and pre-existence of chronic disease are associated with low values for the physical component of the HRQoL questionnaire. In the adjusted model it is observed that obesity, female sex, longer time in compulsory social confinement, and the existence of chronic disease are associated with a low score on the physical component of the HRQoL questionnaire.

Table 4 also shows the analysis for the association with the mental component of the HRQoL questionnaire. In the crude model, female sex, younger age, and time in compulsory social confinement were the variables associated with lower scores on the mental component of the HRQoL questionnaire. In the adjusted model, obesity, female sex, younger age, time in compulsory social confinement, and pre-existence of chronic disease were associated with lower scores on the metal component of the HRQoL questionnaire.

The present study aimed to determine the perception of HRQoL in the population of Metropolitan Lima according to whether or not they had COVID-19. Health-related quality of life (HRQoL) is an indicator that helps us to measure people's self-perception of their health. This can be measured with the questionnaire validated in Peru, the SF-20, ^{21 , 24 , 30} used in this study. Cronbach's alpha, which is the internal consistency reliability coefficient, shows a value of 0.71, which is considered acceptable.

The HRQoL score can also be disaggregated into its physical, mental, and general health components. These can be affected by one or all of them together by different factors.

According to the results found in the present study, the main factor associated with lower HRQoL is the time of compulsory social confinement.

This variable social isolation in the crude and adjusted models showed a statistical significance where the longer the time of confinement, the lower the total HRQoL score and the lower the score in the mental and physical components of HRQoL.

Associated with this, other factors affecting HRQoL were also observed, such as obesity, female sex, and a history of chronic illness. In itself, having or not having COVID-19 did not affect the HRQoL score. This is an important finding as it is assumed that COVID-19 can lead to health impairment. ³² There are likely ethnic or idiosyncratic differences in the response to COVID-19 following an illness. A recent study in Peru shows that patients with COVID-19 do not have a higher rate of postoperative complications than patients without COVID-19. ³³ Further studies will be needed to follow patients with COVID-19 for longer-term follow-up and to have a clearer conclusion on post-COVID-19 effects.

Interestingly, the health perception of the study participants is affected more by the compulsory social confinement than by the disease itself. A recent study on psychiatric teleconsultations in Peru shows that the third leading cause of psychiatric consultation was related to compulsory social isolation (19.7%), the first two being related to control, follow-up, or worsening of mental health problems before the pandemic (41.9%) and related to the appearance or increase of intrafamily conflicts (21.4%). ³⁴

In similar situations, as in the case of Middle East respiratory syndrome (MERS) in 2015 in South Korea, mandatory social confinement for two weeks showed negative effects on mental health even 4-6 months after the end of social isolation. ³⁵ Likewise, a study of 1008 young adult (18-35 years old) residents of the USA reported that higher the level of isolation and lack of social interaction during the context of the COVID-19 pandemic, higher mental disturbances and poorer the performance. ³⁶

Several factors influence the impact that disease outbreaks can have on the mental state of the population, such as lack of knowledge of the possible means of virus transmission, uncertainty about the future, misinformation, and quarantine. These stressful events negatively affected various behaviors, such as eating habits, sleep, physical activity, and sedentary lifestyles. ³⁷ They also cause an increase in anxiety and depression. ³⁸

During the pandemic, an increase in sleep disturbance and insomnia has been reported, as stress and anxiety affect the quality of sleep during the night and even alter the state of energy during the day. ^{37 , 38} In addition, although our study has not focused on sleep disorders associated with the pandemic, this has been reported in several studies. ^{39 , 40} Social confinement times have been shorter than those observed in Peru.

During social isolation, the adoption of bad habits increased, such as higher consumption of caloric and unhealthy foods; lower consumption of fresh fruit and vegetables; and a move away from the Mediterranean diet, which is considered to be healthy. ³⁷

In the case of physical activity, the total blockade, the closure of sports facilities, social restriction, and the increase in hours in front of an electronic device, due to work and study, among others, has caused a decrease in physical activity, and in turn an increase in sedentary lifestyles. ³⁷

Thus, although COVID-19 disease has been described as a fatal disease, it was not the main cause of the damage to the quality of life of the population, but during compulsory social confinement, health risk behaviors increased.

Indeed, the percentage of subjects who underwent compulsory social confinement was similar in those subjects who presented COVID-19 than in those who did not. This is since compulsory social confinement was prolonged, but there was access to massive exposure, such as in the case of markets, banks (government bonds), and public transport, which allowed many people to become infected, who may have been asymptomatic and eventually carried the infection home, infecting other family members with varying degrees of severity.

In Metropolitan Lima, a greater number of food markets was associated with higher incidence and mortality of COVID-19 (p<0.01 for both); these associations persisted when cases (r=0.49; p<0.01) and deaths (r=0.58; p<0.01) were adjusted for population density. ⁴¹

In our study, obesity is a risk factor for lower HRQoL. This corroborates findings from other studies. ⁴² The results of our study show that 57% of the surveyed population perceived weight gain and 67% had a decrease in physical activity during social confinement. According to the Peruvian College of Nutritionists, during the pandemic Peruvians gained an average of 7.7 kg, the main causes being increased caloric food intake and a sedentary lifestyle. ⁴³

The relationship between obesity and HRQOL is negative. sedentary lifestyle and weight gain in the population, which is a risk condition that predisposes to many comorbidities such as predisposes to many comorbidities such as metabolic alterations, dyslipidemias, and even cardiovascular diseases, which affect and cardiovascular diseases, which affect and deteriorate the quality of human life. ^{44 , 45}

In other pathologies, despite having the same care, women show lower HRQoL scores. ⁴⁶ Our results show that women have lower total scores on the HRQoL questionnaire, as well as on its physical and mental components, confirming what has been observed in other pathologies.

A history of chronic illness is also associated with lower scores on the HRQoL questionnaire. ^{47 , 48} The same has been confirmed in our study.

Age has shown different results in our study. For the total score and the mental component, younger age is associated with lower HRQoL scores, while for the physical component older age is associated with lower HRQoL scores.

The young population in compulsory social confinement has been subjected to a high degree of stress and anxiety due to the suspension of the face-to-face university and non-university classes and the use of tele-education involving many hours of the day in front of the computer. In our study more than half of the population studied showed cases of anxiety and/or depression during the period of compulsory social confinement. This would be one of the probable conditions for lower scores on the HRQoL questionnaire.

Having been vaccinated shows a trend towards better HRQoL scores with the second and third doses of the vaccine. The non-significance may be since the number of subjects vaccinated with two or three doses is still insufficient to show statistical significance. Further studies will show whether or not this trend becomes significant.

For healthy people in mandatory social confinement, lifestyle changes, fear of contracting COVID-19 disease, young age, female sex, history of mental illness and lower coping capacity for stress appear to be risk factors for insomnia. ⁴⁹

In Peru, the impact of social isolation may have been greater because of the time in which it has occurred. This confinement has not only been inefficient as events with crowds of people occurred simultaneously while in other situations, such as the suspension of classes for school and university students, but it has also significantly affected our educational level. In addition, the long-standing compulsory confinement has not only failed to reduce infections and deaths, but Peru has one of the highest mortality rates in the world, with more than 200,000 Peruvians having died to date.

The strength of this study was the methodology, which shows within the context of the pandemic the use of technological tools is valuable for an understanding of society and its relationship with health. The instrument used included diverse sections of information, including a validated questionnaire (SF-20) to evaluate de HRQoL, which allowed a wider perspective to analyze causes for the results obtained. This study also shows how the application of health policies or measures should be based on the evaluation and social context.

This study presents certain limitations as well. First, our database was recollected by convenience; therefore, the results present in this paper cannot be generalized for the entire Peruvian population. However, our results show tendencies consistent with other studies. Also, due to social distancing and COVID-19 regulations, the anthropometric measurements were not able to be taken by health workers but were self-reported by the participants. This is a limitation since the margin of error increases; nevertheless, the correlation between measurements was high. Another limitation present was the research tool, the electronic questionnaire, which was more often completed by respondents with higher education and residents of high-income districts, probably also due to the better quality of Internet connection. Therefore, a follow-up is recommended according to the ethnicity and culture of each country or city.

In conclusion, although it is not a study that can be extrapolated to a large population, due to the type of design, this study allows us to have prior knowledge about health-related quality of life and how it has been affected to a large or medium extent in the context of the COVID-19 pandemic. The research team proposes longitudinal follow-ups of the population to avoid adverse outcomes in later life.