An Analysis of Covid-19

CRITICAL APPRAISAL OF AN EPIDEMIOLOGY RESEARCH WORK
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Critical Appraisal of an Epidemiology Research Work
At present, the world is faltering, struggling with the period of ecological epidemiology. Many devastating infectious pathogens are emerging and reappearing. The number of evolving viral zoonotic disease epidemics is increasing. Severe Acute Respiratory Syndrome (SARS), A/H1N1 influenza pandemic, H5N1, and the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) are examples of this infection type. These infections and some other infections caused severe public health effects (Helmy et al., 2020).
(SARS-CoV-2, which causes COVID-19, is among the most significant destructive evolving infectious diseases today. COVID-19 was listed as Public Health Emergency of International Concern (PHEIC) on January 30, 2020 (Rodriguez-Morales et al., 2020). At that time, the World Health Organization classified it as a pandemic on March 11, 2020. The SARS-CoV-2 was also categorized as a "risk group 3" pathogen because its health and global economy pose a very large danger to the community (Kummitha, 2020). The Covid-19 pandemic has brought a huge destructive burden on health, life, and economy and restricted the social activities of all people in the world. It leads to worldwide health and economic crisis; countries closed borders and issue travel bans, closed businesses and schools, and implemented strict quarantine (Bong et al., 2020).
There are several factors involved in the incidence of the Covid-19 pandemic. First is the global spread of the novel SARS-CoV-2, with no immunity and no involvement of human exposure. Second, SARS-CoV-2, as an RNA virus, displays an elevated mutation rate, allowing fast variation, but at the cost of producing non-viable progenies (Schröder, 2020). Moreover, the transmission rate of the virus or its basic copy number (R0) is relatively high. In addition, to date, there is no active treatment against Covid-19.
A study showed that the rapid spread of the first outbreak from the Wuhan to the entire mainland of China might be associated with the spread of transportation. Since Wuhan is among the regions known as a hub for transportation, millions of people were allowed to move out of the city, spreading the virus during the peak travel period of the Spring Festival (Wang et al., 2020). In the second epidemic spread in parts of Asia from China and subsequently, to other continents, international transportation through aeroplanes and cruise ships played a significant role. However, human-to-human transmission is the main transmission mode because respiratory droplets carrying COVID 19 could be thrown out by an infected person while sneezing or coughing (CDC, 2020).
These droplets may go into the lungs through inhalation and infect nearby people. In addition to human-to-human transmission, environmental pollution is also another way of virus transmission. For example, it is well known that if a non-infected individual comes in contact with the objects which are contaminated by the droplets in question followed by touching their mouth, eyes, and nose, COVID-19 may spread indirectly. SARS-CoV-2 may persist stably in aerosols and spread for several hours (Van Doremalen et al., 2020). They could survive several days on plastic or stainless steel. Hence, this could be the potential reason related to in-hospital transmission and hyper-transmission events.
Critical Appraisal of the Research Work
For the critical appraisal of the selected research work, we used a formal critical appraisal tool and presented the findings of the critical appraisal.
Purpose Statement
The purpose of this paper is to critically appraise a peer-reviewed article on the epidemiology of COVID-19 from the perspective of epidemiological surveillance by duly filling the assessment form of the tool at hand.
The criticism follows a formal sequence. The initial part contains the findings of the study with a detailed analysis of the results. Initially, the findings of the study are stated as they are and synthesized with existing literature. It is followed by the critique of those findings in line with the best practices in this context. The next section deals with the limitations of the study that erode the credibility and transferability of the study. In the next section, in tabular form, there is a detailed assessment of the sources used in the given study.
Methods
Sampling: The sample size for the study was 391 patients along with their close contacts up to 1286, including co-travellers and home-mates. The sample size is considered even though not generalizable at a larger scale (Kothari, 2013). It is considered sufficient given the time and resource constraints. The infection at the time when the study was conducted was relatively newer, and it was hard for a sizeable population in a given time. Therefore, the researchers had to fast-track the study to serve as a source of managerial implications. However, for the research to be generalizable globally irrespective of cultural, ethnic, geographic, climatic, and all other disparities, the sample size needed to be at least three times greater and inclusive of a more diverse population.
Methods of Analysis: The data was analyzed using purely quantitative and, within quantitative, statistical methods. Even though the analytical tools used are reliable, it would have significantly added to the credibility of the findings if the researchers had applied cross-tabulation between quantitative data and existing literature (Kothari, 2013). Understandably, the knowledge database on COVID 19 epidemiology was not considerably established by the time when the study was conducted. Therefore, the researchers could have referred to the literature dealing with similar infections experienced in the past or best practices in that regard.
Inferences Drawn
Most of the inferences drawn, such as confirmation, isolation, and contact tracing, are precise while cross-checked with the data at hand. However, the researchers had vaguely concluded regarding the severity of symptoms for children and practices to be employed. The findings contradict other reports and research works suggesting that the children are at the same risk and may develop similar symptoms (from mild to severe) as adults (CDC, 2020; Kelly et al., 2021). Even though the researchers have justifiably concluded that the same control and monitoring interventions are to be considered for children as for adults, it would have added more credibility to the study if the researchers had labelled children's chances to develop serious symptoms as "uncertain" rather than "lower" as it was a premature inference given the inadequate sample size.
Findings of the Research Work
The analysis of the initial COVID 19 cases and their local associates in Shenzhen, China, offers an in-depth understanding of the disease's natural history, spread, and control. The estimates deliver the evidence base for envisaging the impact of the virus, assessing control measures, and regulating global response. The analysis of how the cases were found and the use of the data from exposed but uninfected individuals showed that the infection rate for young children was not less than the average population. Researchers directly evaluated the key transmission parameters and demonstrated that, in the cases that came under observation, the transmission rate was very little.
Assessment of the time distribution between the onset of symptoms and the isolation of cases based on the type of surveillance suggested that the combination of enhanced surveillance and case isolation may be the cause of these low transmission rates. These results showed a positive impact of Shenzhen's increased surveillance and isolation. Nevertheless, uncertainty about the asymptomatic cases missed by monitoring and their capability to spread SARS-CoV-2 must weaken the hope of preventing the Covid-19 pandemic through these measures. This study further backed the concept of COVID-19 as a disease with a short incubation period (four to six days on average) but a longer clinical course. It takes several weeks for patients to die or get well (Chen et al., 2020; Backer et al., 2020).
However, it is worth noting that the percentage of cases that take 14 days or above to grow symptoms is higher (5%) than the assessed in a previous study (1%) (Lauer and Grantz, 2020). Concentrating on cases identified by contact-based surveillance provides hints to the previous COVID-19 features. As RT-PCR testing of infected persons is almost universal, it can be assumed that these cases reflect the average SARS-CoV-2 infection better than those found through symptom monitoring. In contact-based surveillance groups, the slight trend of male or older cases (outside the basic population distribution) disappeared. In addition, in that group, the cases that showed no symptoms at all at the first clinical evaluation remained 20%, and almost 30% were not having fever. This surveillance agrees with the rather high asymptomatic carrier rate but below the level recommended by some model studies, 19, although the sensitivity of RT-PCR is not perfect (Fang, 2020).
In Shenzhen, the spread of SARS-CoV-2 was likely to occur among very close contacts, i.e., individuals living in the same family. But, in this group also, less than one-sixth of the acquaintances (secondary morbidity rate of 11-15%) were infected. Overall, the forward progression of each primary case was observed, even < one (0·4). As mentioned above, the low transmission level may be partly due to the effects of surveillance and isolation; however, it is equally possible that unnoticed transmission also had a role. It was also estimated that the rate of over-dispersion of the number of cases triggered through each infected individual was quite high. Even if surveillance and quarantine force R below 1, ...