The present study showed that food-insecure people with COVID-19 had a longer recovery time. Also, our findings showed that food insecurity significantly increases the likelihood of hospitalization, and after adjusting for all confounding variables, people with food insecurity are 3.9 times more likely to be hospitalized than those in the food secure group. The present study is one of the few studies to examine food security in patients with COVID-19. Other studies have addressed food security in the general population.
In the present study, food-insecure individuals were significantly more likely to be hospitalized than the food secure group, and this finding remained significant after adjusting for variables. Other studies show that people in food-insecure households (especially children) are significantly more likely to be hospitalized for infectious diseases . Besides, studies cite reasons such as poor diet quality, medication non-adherence or not having enough money to buy medication, lack of control over some chronic diseases such as diabetes, as factors for more possibility to be hospitalized in food-insecure people .
Food choices based on the level of food security can make a significant contribution to the prevention or progression of respiratory diseases. Research shows that the quality of food intake in patients with malnutrition or food insecurity is reduced due to the greater tendency of these people to consume western diets to supply their calories . In the western diet, a large portion of foods are related to sugar, refined grains, and saturated fats, and on the other hand, this group consumes a small amount of fiber and unsaturated oils, which are very good for health . Therefore, it can be said that this issue may be one of the reasons for the hospitalization of more people with food insecurity than the food secure group in the present study.
Our findings show that lack of food security significantly increases the recovery time after getting COVID-19. In fact, food insecurity is associated with poor diet quality on the one hand  and on the other hand, people with food insecurity are more likely to develop chronic diseases such as diabetes  and obesity . These factors may be one of the reasons why food-insecure adults recover longer than food-secure ones. Also, food-insecure people may avoid medication because they do not have enough money for food , which itself in the COVID-19 pandemic may worsen or prolong the symptoms of the disease.
Changes in the level and extent of food insecurity during the COVID-19 pandemic can have a significant impact on the consequences of this pandemic so that increasing levels of food insecurity are associated with mortality, morbidity, and disease burden in many non-communicable diseases  and lack of food security can exacerbate and prolong the effects of COVID-19 . In addition, the total amount of energy received can be directly related to the duration of recovery, so that the WHO considers the amount of energy consumed between 2500 to 3400 kcal per person per day as a measure of healthy living  but it seems that most people with food insecurity receive far fewer calories.
According to our findings, food insecurity was associated with low income or poor economic status, illiteracy, and rural living. Food insecurity and low incomes make people more vulnerable to coronavirus. Because on the one hand, these people cannot buy all the food they need in one place and this causes more travel and on the other hand, these people are more exposed to severe hunger crises because they do not have enough financial resources to buy sufficient food . Also, in Iran, people with lower incomes usually live in rural areas.
The COVID-19 pandemic has limited all stages of the food supply chain, including processing, production, procurement, and distribution . In addition, in the recent pandemic, business closures, social distancing policies, fear of shopping, and fear of going out to shop because of the risk of exposure to the virus have led to increased food insecurity [9, 27]. Besides, food availability, which is one of the categories of food security, is disrupted due to the loss of all or part of the income and the fear of depletion of food stocks . It is very clear that food insecurity and changes in eating habits and behaviors in the short-term can have a significant impact on the health of society, especially children [27, 28]. The COVID-19 pandemic complicated the strategies used by low-income families further to combat food insecurity, and in some cases, families were unable to maintain their food security . The negative impact may last for years, especially in food insecure and low-income households .
Studies in other countries have shown that the COVID-19 pandemic reduced working hours and income in many households. For example, 43% of American households reported losing their jobs or their salaries due to the pandemic. This percentage was even higher than 50% in lower-income households . Moreover, this seems to be even worse in countries that had a higher percentage of food insecurity before the COVID-19 outbreak .
Research has shown that income plays an important role in food choices, so that in middle- and low-income countries, poor people spend more than a quarter of their income on basic foods such as wheat, rice, and corn, while this figure was only 14% in non-poor families . Besides, research shows that poor families spend about 50 percent of their income on non-essential foods such as fruits, vegetables, and animal proteins, and reduction of the revenue causes poor families to even give up consuming these food groups . This reduces the dietary diversity in low-income families, as a result, the intake of micronutrients and antioxidants decreases, and eventually endangers their health status [11, 30]. Therefore, choosing cheap foods and having an imbalanced diet in families with food insecurity, considering the fact that these foods are high in fat and sugar, is itself a risk factor in the development of respiratory diseases .
Having a balanced diet is an integral part of controlling risk management strategies in pandemics, and the recent pandemic is no exception . One of the most frequent recommendations to prevent COVID-19 disease is the high intakes of fruits and vegetables, because this food group is high in antioxidants, they are very effective in boosting the immune system . In addition, the consumption of animal proteins during the recovery period of the disease is highly recommended, because it promotes faster recovery . It is evident that a decrease in income level makes food insecure people unable to consume fruits, vegetables, and proteins, and their food basket tends to consume cheap, high-calorie foods [33, 34]. This has a significant effect on lowering the level of the immune system and thus worsening the disease and the duration of it in case of having COVID-19.
There is ample evidence that a balanced diet has a significant effect on the immune system and disease susceptibility. Meanwhile, studies have shown that certain nutrients are very effectual on the effective activity of the immune system, this mechanism may be caused by the activation of some cells, changes in the production of signaling molecules, and the effect on gene expression . Therefore, deficiency of some macronutrients such as protein and some micronutrients such as iron, zinc, vitamins A, E, B6, B12, which mainly play an important role in maintaining the function of the immune system, in addition to low energy intake can reduce immune system activity and increases the likelihood of susceptibility to infection .
On the other hand, having an unbalanced diet, in the long run, activates the innate immune system and inhibits the adaptive response of the immune system to increased oxidative stress, as a result, it causes a delayed response in the adaptive response of the immune system, which is considered as one of the most important strategies of the immune system against pathogens . Therefore, it is recommended to improve food habits and security by having a balanced diet and avoid western diets it may be one of the most important ways to boost the immune system and control infectious respiratory diseases .
Evidence suggests that food insecurity can lead to poor health outcomes by activating inflammatory pathways [38, 39]. Food insecurity can independently increase the level of inflammatory factors such as C-reactive protein (CRP) , IL-6, and tumor necrosis factor (TNF) receptor 1 . On the other hand, food insecurity itself is considered a powerful stress factor, as studies show, stress also causes an increase in inflammatory factors in the individual . An increase in these factors may lead to an increase in the level of inflammation in the body, resulting in a late recovery of food insecure people with COVID-19 .
The present study had some limitations. First, due to the nature of the study (cross-sectional), the cause-and-effect relationship cannot be extracted. Second, in the present study, factors related to mental states such as stress and anxiety were not examined, which is suggested that since food insecurity plays an important role in people’s mental health, these factors be examined in future studies. Third, in this study, the interview was conducted by telephone, which in this type of interview, there was a possibility of reporting an error. Fourth, food insecurity was assessed using the USDA retrospective questionnaire, since this questionnaire examines the level of food security in the past year, there is a possibility of non-recall error.
One of the strengths of the present study is that according to the research, this study is one of the first studies to investigate the relationship between food security with the probability of hospitalization and the length of the recovery period in patients with COVID-19. Also, the use of an 18-item USDA validated questionnaire (not a short-form version) to assess food security adds credibility to our study. The sample size examined in the present study also adds to the strength of the present study because the total sample size was definitively positive for COVID-19. It is suggested that prospective studies be conducted in the future to better understand the impact of coronavirus pandemic on food security.