A rapid antigen test (RAT) or rapid antigen detection test (RADT), is a rapid diagnostic test suitable for point-of-care testing that directly detects the presence of an antigen. It is used to detect SARS-CoV-2 that cause COVID-19. This test is one of the type of lateral flow tests that detect protein, differentiate it from other medical tests such as antibody tests or nucleic acid tests, of either laboratory or point-of-care types. Generally 5 to 30 minutes only will take to get result and, require minimal training or infrastructure, and cost effective (1).
Sri Lanka was extremely vulnerable to the spread of COVID-19 because of its thriving tourism industry and large expatriate population. Sri Lanka almost managed two waves of Covid-19 pandemic well, but has been facing difficulties to control the third wave. The Sri Lankan government has executed stern actions to control the disease including island-wide travel restrictions. The government has been working with its development partners to take necessary action to mobilize resources to respond to the health and economic challenges posed by the pandemic (2) (3).
The COVID 19 outbreak is dangerous and fatal for elderly population. Since the beginning of the actual SARS-CoV-2 outbreak there were an evident that older people were at higher risk to get the infection and develop a more severe with bad prognosis. The mean age of patients that died was 80 years. The majority of those who are infected, that have a self-limiting infection and do recover are younger. On the other hand, those who suffer with more severe disease require intensive care unit admission and finally pass away are older (4).
Sandoval. M., et al mentioned that the number of patients who are affected by SARS-CoV-2 with more than 80 years of age is similar to that with 65–79 years. The mortality rate in very elderly was 37.5% and this percentage was significantly higher compared to that observed in elderly. Further their findings were suggested that the age is a fundamental risk factor for mortality (5).
Since February 2020, more than 27.7 million people in US have been diagnosed with Covid-19 (6). Rates of COVID-19 deaths have increased across the Southern US, among the Hispanic population, and among adults aged 25–44 years (7). Young adults are at increased risk of SARS-CoV-2 because of exposure in work, academic, and social settings. According to the several database of different health organizations young adult, aged 18-29, were confirmed Coid-19 (9).
Go to:Amid of coronavirus disease 2019 (Covid-19) pandemic, much emphasis was initially placed on the elderly or those who have preexisting health conditions such as obesity, hypertension, and diabetes as being at high risk of contracting and/or dying of Covid-19. But it is now becoming clear that being male is also a factor. The epidemiological findings reported across different parts of the world indicated higher morbidity and mortality in males than females. While it is still too early to determine why the gender gap is emerging, this article point to several possible factors such as higher expression of angiotensin-converting enzyme-2 (ACE 2; receptors for coronavirus) in male than female, sex-based immunological differences driven by sex hormone and X chromosome. Furthermore, a large part of this difference in number of deaths is caused by gender behavior (lifestyle), i.e., higher levels of smoking and drinking among men compared to women. Lastly, studies reported that women had more responsible attitude toward the Covid-19 pandemic than men. Irresponsible attitude among men reversibly affect their undertaking of preventive measures such as frequent handwashing, wearing of face mask, and stay at home orders.
The latest immunological study on the receptors for SARS-CoV-2 suggest that ACE2 receptors are responsible for SARS-CoV-2. According to the study by Lu and colleagues there are positive correlation of ACE2 expression and the infection of SARS-CoV (10). Based on the positive correlation between ACE 2 and coronavirus, different studies quantified the expression of ACE 2 proteins in human cells based on gender ethnicity and a study on the expression level and pattern of human ACE 2 using a single-cell RNA-sequencing analysis indicated that Asian males had higher expression of ACE 2 than female (11). Conversely, in establishing the expression of ACE 2 in the primary affected organ, a study conducted in Chinese population found that expression of ACE 2 in human lungs was extremely expressed in Asian male than female (12).
A study by Karnam and colleagues reveled that CD200-CD200R and sex are host factors that together determine the outcome of viral infection. Further a review on association between sex differences in immune responses stated that sex-based immunological differences contribute to variations in the susceptibility to infectious diseases and responses to vaccines in males and females (13). The concept of sex-based immunological differences driven by sex hormone and X chromosome has been well demonstrated via the animal study by Elgendy et al (14) (35). They were concluded the study that estrogen played big role in blocking some viral infection.
The biological differences in the immune systems between men and women may cause impact on fight for infection. Females are more resistant to infections than men and which mediated by certain factors including sex hormones. Further, women have more responsible attitude toward the Covid-19 pandemic than men such as frequent hand washing, wearing of face mask, and stay at home (15).
Most of the studies with Covid-19 patients indicate that males are mostly (more than 50%) affected than females (16) (17) (18). Although the deceased patients were significantly older than the patients who survived COVID-19, ages were comparable between males and females in both the deceased and the patients who survived (18).
A report in The Lancet and Global Health 5050 summary showed that sex-disaggregated data are essential to understanding the distribution of risk, infection and disease in the population, and the extent to which sex and gender affect clinical outcomes (19). The degree of outbreaks which affect men and women in different ways is an important to design the effective equitable policies and interventions (20). A systematic review and meta-analysis conducted to assess the sex difference in acquiring COVID-19 with 57 studies that revealed that the pooled prevalence of COVID-19 confirmed cases among men and women was 55% and 45% respectively (21). A study in Ontario, Canada showed that men were more likely to test positive (22) (23). In Pakistan 72% of COVID-19 cases were male (24). Moreover, the Global Health 5050 data showed that the number of COVID-19 confirmed cases and the death rate due to the disease are high among men in different countries. This might be because behavioral factors and roles which increase the risk of acquiring COVID-19 for men than women. (25) (26) (27).
Men mostly involved in several activities such as alcohol consumption, being involved in key activities during burial rites, and working in basic sectors and occupations that require them to continue being active, to work outside their homes and to interact with other people even during the containment phase. Therefore, men have increased level of exposure and high risk of getting COVID-19 (28) (29) (30).
Men tended to develop more symptomatic and serious disease than women, according to the clinical classification of severity (31). The same incidence also noticed during the previous coronavirus epidemics. Biological sex variation is said to be one of the reasons for the sex discrepancy in COVID-19 cases, severity and mortality (32) (33). Women are in general able to stand a strong immune response to infections and vaccinations (34).
The X chromosome is known to contain the largest number of immune-related genes in the whole genome. With their XX chromosome, women have a double copy of key immune genes compared with a single copy in XY in men. This showed that the reaction against infection would be contain both innate and adaptive immune response. Therefore the immune systems of females are generally more responsive than females and it indirectly reflects that women are able to challenge the coronavirus more effectively but this has not been proven (32).
Sex differences in the prevalence and outcomes of infectious diseases occur at all ages, with an overall higher burden of bacterial, viral, fungal and parasitic infections in human males (36) (37) (38) (39). The Hong Kong SARS-CoV-1 epidemic showed an age-adjusted relative mortality risk ratio of 1.62 (95% CI = 1.21, 2.16) for males (40). During the same outbreak in Singapore, male sex was associated with an odds ratio of 3.10 (95% CI = 1.64, 5.87; p ≤ 0.001) for ITU admission or death (41). The Saudi Arabian MERS outbreak in 2013 - 2014 exhibited a case fatality rate of 52% in men and 23% in women (42). Sex differences in both the innate and adaptive immune system have been previously reported and may account for the female advantage in COVID-19. Within the adaptive immune system, females have higher numbers of CD4+ T (43) (44) (45) (46) (47) (48) cells, more robust CD8+ T cell cytotoxic activity (49), and increased B cell production of immunoglobulin compared to males (43) (50). Female B cells also produce more antigen-specific IgG in response to TIV (51).
Age-related changes in the immune system are also different between sexes and there is a marked association between morbidity/mortality and advanced age in COVID-19 (52). For example, males show an age-related decline in B cells and a trend towards accelerated immune ageing. This may further contribute to the sex bias seen in COVID-19 (53).
Hence, this single center, retrospective, data oriented study performed to identify the gender age influences the RAT results and the rate of positive cases before and after the lockdown.
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