Within no time, Coronavirus disease (COVID-19) has emerged as an outbreak, then as an epidemic, and finally now as a pandemic. However, Coronavirus (CoV) is not the first-ever occurrence as it was initially discovered in the 1960s, and since then, several types of CoV were identified amongst which Severe Acute Respiratory Syndrome-CoV (SARS-CoV) and Middle East Respiratory Syndrome-CoV (MERS-CoV) are of importance. With hundreds and thousands of new cases and death tolls increasing day-by-day, COVID-19 is aiming to outreach the other pandemics, which is, in fact, raising a lot of concern among public health agencies and as well as general public across the globe. In this era of the 21st century, despite the advanced technologies, especially leading developments in the field of medicine and rapid growth in the healthcare sector, the entire world is still struggling to combat this pandemic, even after four months of its emergence. So, is COVID-19 difficult to tackle and dangerous compared to other pandemics, if so, what characteristics of this pandemic are making it more challenging? Through this opinion, authors sought to explore the potential reasons for how COVID-19 differs from the recent CoV pandemics and what makes it stand alone. The following are considerable characteristics that enumerate the divergence of the COVID-19 while comparing with the other CoV pandemics.
Incubation Period: The incubation period is the time elapsed between the exposure and the onset of the symptoms. COVID-19 is believed to have a longer incubation period of 1-14 days (median of 5-6 days), compared to SARS [2-7 days (4 days)] and MERS [1-14 days (4.8 days)], which makes it challenging to diagnose the infected individuals. Typically, diseases with longer incubation periods would need longer active monitoring and quarantine periods to control the spread. Unlike COVID-19, SARS generally transmit after individuals start showing symptoms, which was a major reason that helped in being able to contain the SARS outbreak. Besides, compared to COVID-19, contact tracing became effortless with SARS as symptoms were severe and, therefore, easier to identify and contain.
Serial Interval: The serial interval of any infectious or communicable disease is the duration between symptom onset of a primary case and of its secondary cases (i.e., the time between two successive cases of transmission). The mean serial interval for COVID-19 is estimated to be 3.9 days, while it is 8.4 days for SARS and 14.6 days for MERS, which means that COVID-19 can spread faster than SARS and MERS.
Transmission Rate: During any disease outbreak, the rate of transmission would play a decisive role, especially while making comparisons with the other outbreaks. With a trait of exponential growth, in a very short span of time, the confirmed cases attributed to the COVID-19 have crossed 3.2 million, whereas the SARS and MERS account for a total of 8,089 and 2,500 cases, throughout their entire pandemic periods.
Reproductive Number (R🞅): The reproductive number refers to the spreading capacity of a virus, which infers on average, how many individuals would get sick by each infected person. If the R🞅 is less than 1, then that disease would have a low potential for sustained community transmission. Based on the available evidence, the R🞅 for COVID-19 is 2.8-3.9, which means about two to four people will get the disease with the virus from the infected person, whereas the R🞅 for SARS was <2 and <1 for MERS.
Case-Fatality Rate: The case-fatality rate (CFR) is the ratio between the deaths and confirmed cases of that particular disease. The total number of deaths attributed to the COVID-19 as of 1 May are 233,363, while it was 744 deaths for SARS, 866 for MERS, leading to the CFR of 7.2%, 9% and 34% for COVID-19, SARS and MERS, respectively. Although CFR of SARS and MERS were higher, COVID-19 has actually led to more fatalities.
Treatment availability: So far, there is no medication nor a treatment regimen approved for the management of COVID-19, while the vaccine is likely to be available in a year from now, i.e., by 2021, in the best-case scenario. Whereas, during the SARS pandemic, certain antivirals and steroids have shown beneficial effects for some patients and also a vaccine was made available by the end of the pandemic. Similarly, certain monoclonal antibodies and antivirals have demonstrated promising effects in in-vitro and animal models during the MERS outbreak.
In a nutshell, the recent pandemic of SARS-Cov-2 has now spread at an exponential rate, leaving no clue where and how it ends. Although SARS-CoV-2 belongs to the same family of SARS and MERS, SARS-CoV-2 seems to be fatal. However, as time passes, the ultimate comparison of this global pandemic to other pandemics could be decided and well established.