IO – Since SARS – CoV-2 (Covid-19) first emerged in Wuhan, China, around the end of 2019, many variants have cropped up in various parts of the world, from Alpha in the UK, Beta in South Africa, Delta in India, Gamma in Brazil and now Omicron, which was first detected in South Africa and is responsible for the fourth wave in the country with more than 23,000 cases a day by mid-December 2021.
Since May 2021, the World Health Organization (WHO) has decided to use letters of the Greek alphabet instead of complicated numbers to name the constantly mutating Covid variants to make it simpler and easier for non-scientific public to say and remember. Thus, the first widely known variant of concern (VOC) — B.1.1.7 — is named Alpha, followed by B.1.351 (Beta), P1 (Gamma), B.1.617.2 (Delta) and B.1.1.529 (Omicron). Omicron is the fifteenth letter of the Greek alphabet, meaning that there have been many variants after Delta, but we may have never heard of them because they were only designated by the WHO as either variants under monitoring (VUM) or variants of interest (VOI). VOC is the highest alert level.
The WHO immediately classified Omicron under VOC because of it has high number of genomic mutations (more than 30 changes to its spike protein, which it uses to latch onto a human cell receptor), meaning that it is up to 500% more infectious than previous VOCs and is more capable of evading vaccine protection. Thus, it poses new, serious danger to the world still reeling from the protracted pandemic and threatens to undone the vaccination progress.
Currently, WHO is coordinating with many researchers around the world to better understand the characteristics of Omicron. The UN’s public health body encourages countries to share data of Omicron-fueled transmission, severity level (including symptoms), vaccines effectiveness against it, diagnostic tests, as well as results of treatment as it quickly rips through the global population and threaten to derail a fragile recovery. (FIGURE-1)
Omicron vs. Delta
Covid-19, a type of RNA virus which has ribonucleic acid as its genetic material, is known to have high mutation rates. These mutations will lead to different characteristics and symptoms than its predecessors. Research has shown that Omicron is the most transmissible variant yet. While a person infected with Alpha will pass the virus on to three people and Delta believed to be 10 times more virulent than Alpha, Omicron is at least 70 times more contagious than Delta, according to a study by the University of Hong Kong. No wonder it is dubbed “super mutant”.
Another key difference is, while Omicron is more virulent than Delta, it is less likely to cause more severe symptoms and hospitalization especially on the fully vaccinated, according to a joint study in South Africa. However, Omicron is said to be 10 times more capable of reinfecting Covid-19 survivors than Delta.
In many cases, Omicron is also observed to be milder, especially among the young, fully vaccinated, or patients without comorbidities. However, preliminary data regarding the severity level is still limited, pending further research. Given the higher transmission rate, the world needs to be extra vigilant as Omicron can quickly swamp the public health system.
Common symptoms among Omicron patients are muscle pain, night sweats, low-grade fever, severe fatigue, itchy throat, headache, persistent dry cough, and in more severe cases, shortness of breath and chest pain. These symptoms are quite different compared to Delta.
Omicron-induced fever is relatively mild, and the throat is usually just itchy, not sore. This is because Omicron is more often found in the respiratory tract while Alpha, Beta, and Delta attack the lungs, thus cause more severe symptoms like more intense coughing and shortness of breath, and often high fever, chills, loss of smell or anosmia, stuffy nose, sore throat, desensitized tongue, sore throat, fatigue, muscle pain, headache, nausea, vomiting and diarrhea. (FIGURE-2), (FIGURE-3).