SARS-COV-2 IN THE POST-PANDEMIC ERA: EMERGING VARIANTS, LONG COVID, DIAGNOSTIC ADVANCES, VACCINATION STRATEGIES AND THERAPEUTIC PERSPECTIVES
AUTHOR(S): Ms. Vedika S. Patil*, Ms. Sakshi G. Jadhav, Ms. Sanika K. Kole, Ms. Shravani P. Ghode
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Abstract:
The emergence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has resulted in a rapidly evolving global health challenge, with Coronavirus Disease 2019 (COVID-19) transitioning from an acute pandemic to a persistent public health concern. Continuous viral evolution has led to the emergence of multiple variants and sub lineages with altered transmissibility, immune evasion, and clinical characteristics. This review provides an updated overview of the evolving landscape of SARS-CoV-2 infection, encompassing epidemiology, viral pathogenesis, emerging variants, diagnostic advancements, vaccination, therapeutic strategies, and post-acute sequelae of COVID-19, commonly referred to as Long COVID. Particular emphasis is placed on the molecular mechanisms underlying SARS-CoV-2 infection, including spike protein-mediated interaction with angiotensin-converting enzyme 2 (ACE2) and host proteases such as transmembrane serine protease 2 (TMPRSS2), as well as the dysregulated immune responses associated with severe disease and organ injury. The review further discusses major SARS-CoV-2 variants, including Alpha, Beta, Gamma, Delta, and Omicron, along with subsequent Omicron sublineages and their implications for immune escape and disease transmission. Advances in molecular, antigen-based, and serological diagnostic approaches, including multiplex RT-PCR and immunoassay-based methods, are also examined. In addition, the impact of vaccination, booster strategies, breakthrough infections, and global disparities in vaccine access is discussed. Emerging evidence concerning Long COVID, including persistent multisystem manifestations and proposed mechanisms such as immune dysregulation, endothelial dysfunction, microclot formation, and mitochondrial abnormalities, is highlighted. Finally, current therapeutic and preventive approaches are reviewed, emphasizing the need for continued surveillance, improved diagnostic strategies, vaccination, evidence-based treatment, and integrated public health measures. Collectively, this review highlights the continuing evolution of SARS-CoV-2 and the importance of adaptive strategies for reducing the long-term clinical and public health burden of COVID-19.
Keywords:
SARS-CoV-2; COVID-19; Emerging Variants; Long COVID; Diagnostic and Therapeutic Strategies
INTRODUCTION
SARS-CoV-2 infectivity and related fatality rates have declined since the height of the COVID-19 pandemic(1). However, the increasing number of novel SARS-CoV-2 variants, including KP.2, KP.3, and LB.1, continues to put society at danger(2). Furthermore, even after recovering from the acute phase of the illness, a significant percentage of people are currently enduring chronic COVID-19 symptoms. Consequently, COVID-19 continues to be a public health issue(3). The advent of new SARS-CoV-2 variations may reduce the effectiveness of early detection and diagnostic testing, treatments, and vaccinations for this pandemic(4). An up-to-date summary of COVID-19's development, detection techniques, and therapeutic approaches is given in this study. Maintaining control over the current endemic condition requires constant updates on our knowledge of SARS-CoV-2(5).
EPIDEMIOLOGY:
Coronavirus : A new coronavirus (SARS-CoV-2), a positive-sense single-stranded RNA virus, is the cause of coronavirus illness 2019 (COVID-19). Alpha (α), Beta (β), Gamma (γ), and Delta (δ) are the four genres of coronavirus(6). While the Gamma and Delta subtypes mostly cause illnesses in birds, the Alpha and Beta subtypes are clinically significant because they can cause infectious disorders in people(7). Bats gave rise to the Alpha and Beta subtypes, whilst birds gave rise to the Gamma and Delta subtypes(8). In the middle of the 1960s, the first human coronavirus was discovered(9). There are now seven different kinds of coronaviruses that can infect people. Common human coronaviruses include OC43 and HKU1, which are classified as beta coronaviruses, and 229E and NL63, which are classified as alpha coronaviruses(10). These viruses have the potential to cause minor upper respiratory tract infections. In the meantime, serious respiratory tract infections can be brought on by other human coronavirus strains(11). These are beta coronaviruses, specifically MERS-CoV, SARS-CoV, and SARS-CoV-2(12).
Origin of COVID-19 : The first COVID-19 outbreak began in December 2019 when hospitals in Wuhan, Hubei Province, China, reported a number of inexplicable pneumonia cases. The Huanan Wet Seafood Wholesale Market in Wuhan was the site of the first documented outbreak, which subsequently began to spread over the globe(13). At first, the cause was thought to be viral pneumonia. Later, a new coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was found to be the culprit(14). Due to similar genetic and evolutionary histories, SARS-CoV-2 was named after SARS-CoV. SARS-CoV is the cause of the SARS outbreak that occurred in China in 2002–2003. Since the first SARS-CoV outbreak transferred from animals to people, COVID-19 was initially believed to be a zoonotic illness(15). Scientists believed that the source of SARS-CoV transmission was similar to that of SARS-CoV-2. Early in 2020, the majority of COVID-19 patients had gone to the fish and wild animal market, which offered live animals including bats and snakes(16). Thus, the transmission pathway was thought to be direct contact and ingestion of wild animals. The Chinese government's initial reaction was to close animal wet markets because of their unsanitary conditions. But the illness continued to spread quickly around the globe(17). In March 2020, the World Health Organization (WHO) treated COVID-19 as a pandemic and proclaimed it a worldwide health emergency(18). What effect does COVID-19 have on the world's health? The top ten nations with the most COVID-19 cases reported to the WHO as of April 13, 2024, are displayed in Figure 1. The three most populous nations in the world had the greatest number of COVID-19 cases reported, as the figure illustrates. India, the world's most populous nation, was third on the list with nearly 45 million COVID-19 cases. China, the nation with the second-highest population, was second on the list with nearly 99 million COVID-19 cases(19). The United States, the third most populous nation, led the list with approximately 103 million COVID-19 cases. More than 35% of all COVID-19 cases worldwide are found in these three nations. Over 700 million infections and 7 million fatalities occurred globally by the end of 2023(20).
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