EDITORIAL |
https://doi.org/10.5005/jp-journals-10028-1679 |
COVID-19… Where are We in 2024?
1–5Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
Corresponding Author: Vikas Suri, Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India, e-mail: surivikas9479@gmail.com
How to cite this article: Suri V, Singh H, Dhibar DP, et al. COVID-19… Where are We in 2024? J Postgrad Med Edu Res 2024;58(4):153–154.
Source of support: Nil
Conflict of interest: None
A new viral infection emerged in Wuhan, Hubei province, China, on December 12, 2019. Initially known as 2019-nCoV, this single-stranded, positive-sense ribonucleic acid (RNA) virus was later named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The World Health Organization (WHO) officially named the disease COVID-19 on February 11, 2020. The virus spread rapidly throughout the world, causing severe, life-threatening complications. The WHO declared COVID-19 a public health emergency of international concern in January 2020 and a pandemic in March 2020. According to the WHO, as of July 2024, there were 775,731,698 confirmed cases and 7,054,891 deaths of COVID-19 in 223 countries or regions worldwide.
Early studies suggest a zoonotic origin for the coronavirus, with bats being a probable source. Phylogenetic analysis shows an 88% similarity between SARS-CoV-2 and two SARS-like coronaviruses from bats (bat-SL-CoVZC45 and bat-SL-CoVZXC21). Compared to previously known human coronaviruses, SARS-CoV-2 has a higher transmission rate. It belongs to the Coronaviridae family (subfamily Orthocoronavirinae) and can cause a range of diseases, including mild colds, SARS, Middle East respiratory syndrome (MERS), and COVID-19.1 The current outbreak is the third coronavirus outbreak in humans in the past two decades.2 The ability of coronavirus to infect multiple host species is due to high-frequency mutation, which is a result of the instability of the RNA-dependent RNA polymerase along with higher rates of homologous RNA recombination.3,4
SARS-CoV-2 has low pathogenicity and moderate transmissibility, with an infection fatality rate (IFR) of 0.3–0.6%. Transmission involves a combination of viral, host, and environmental factors. SARS-CoV-2 primarily targets the angiotensin-converting enzyme 2 (ACE2) receptors situated on the epithelial cells of the respiratory system, alveolar type II epithelial cells, and other respiratory tract cells.5 The widespread occurrence of these ACE2 receptors in other organ systems, such as the esophagus, ileocolonic cells, and kidney, explains the systemic manifestations of the virus.
The primary transmission route is respiratory, through contact and droplet transmission. Infected secretions, such as saliva or respiratory droplets (>5–10 µm in diameter), can transmit the virus through close contact (within 1 m) with symptomatic individuals. There is no evidence of airborne transmission outside medical settings, nor any confirmed evidence of transmission via fomites. Though SARS-CoV-2 RNA has been found in urine and feces, transmission through these routes is unconfirmed. Bloodborne transmission is unlikely due to low viral titers in blood. There is no evidence of intrauterine transmission or increased risk from breastfeeding. Humans infected with SARS-CoV-2 can infect other mammals such as dogs, cats, and farmed mink.6
Patients with SARS-CoV-2 infection may have mild to asymptomatic illness, but some rapidly progress to acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome (MODS), and death.7 Less common symptoms include nasal congestion, sore throat, headache, hemoptysis, and diarrhea. Some patients have kidney injury and acute myocardial injury. Elderly patients and those with underlying comorbid conditions such as diabetes mellitus, hypertension, cardiovascular disease, chronic lung disease, chronic kidney disease, chronic liver disease, and obesity are at a higher risk. Patients with two or more comorbidities, superimposed with frailty, form the highest risk group.
Laboratory findings are nonspecific but may include elevated C-reactive protein (CRP), decreased albumin, elevated erythrocyte sedimentation rate (ESR), eosinopenia, lymphopenia, and raised lactate dehydrogenase (LDH). Procalcitonin levels may be raised in the presence of secondary bacterial sepsis.
Nucleic acid amplification testing (NAAT), most commonly with a reverse-transcription polymerase chain reaction (RT-PCR) assay, to detect SARS-CoV-2 RNA from clinical specimens/swabs is the preferred initial diagnostic test for COVID-19. RT-PCR can be performed on various types of samples, and the sensitivity of the test depends on the type of sample used for the test. Different types of samples used for NAAT are nasopharyngeal, oropharyngeal, saliva, sputum, lower respiratory samples such as tracheal aspirate or bronchoalveolar lavage (BAL) fluid. The primary and preferred sampling method is from the upper respiratory tract (throat) with or without accompanying nasopharyngeal swabs. The specificity of RT-PCR is very high, although it may result in false-positive results. On the contrary, the sensitivity of RT-PCR is estimated to be around 66–80%.8 The antigen testing method may be used for initial screening, but as its sensitivity is lower than that of NAATs, a negative antigen test needs to be confirmed with NAAT. “Loop-mediated isothermal amplification (LAMP)” technology has shown great potential with an estimated sensitivity of 97.5% and a specificity of 99.7%. “Enhanced recombinase polymerase amplification (eRPA)” is more isothermal than other applications and helps in early diagnosis of COVID-19. The immunoglobulin M (IgM) antibody, though it appears within the first 3–5 days of infection, is more reliable as a diagnostic marker for acute COVID infection after 2 weeks of onset of symptoms. Radiological modalities, such as chest X-rays and high-resolution computed tomography (CT) scans, are better used to monitor disease progression rather than as diagnostic tools, as a normal X-ray or CT scan does not rule out infection.9
Various biomarkers have been shown to predict severe COVID-19 disease. An increased white blood cell (WBC) count, decreased lymphocyte/platelet count, high interleukin-6 (IL-6), high D-dimer, and high serum ferritin levels are suggestive of progressive and severe disease. To date, no specific biomarker has been successfully found to predict increased mortality in COVID-19.
COVID-19 management is primarily supportive, focusing on symptomatic relief and preventing respiratory failure. Nirmatrelvir–ritonavir, a combination of oral protease inhibitors, may be considered for symptomatic outpatients at risk of progression to severe disease. It substantially reduces the risk of hospitalization and mortality in some high-risk outpatients with mild to moderate COVID-19 (i.e., no hypoxia). Remdesivir, a nucleotide analog that inhibits the SARS-CoV-2 RNA polymerase, is used for severe cases but offers no mortality benefit, only reducing hospital stay duration. Recent data also advocate the use of remdesivir in symptomatic outpatients who are at risk of severe disease and cannot use nirmatrelvir–ritonavir. Dexamethasone is recommended for severe or critical cases with hypoxia. Other glucocorticoids can be used if dexamethasone is unavailable. Tocilizumab, an IL-6 receptor blocker, is used for severe or critical cases with elevated systemic inflammation markers.10
Though COVID-19 has been raging for the last few years, much more is needed to diagnose it early and predict its severity. Many gaps in management have been filled, but much more still needs to be done.
REFERENCES
1. Zhu N, Zhang D, Wang W, et al. A novel coronavirus from patients with pneumonia in China, 2019. N Engl J Med 2020;382(8):727–733. DOI: 10.1056/NEJMoa2001017
2. Munster VJ, Koopmans M, van Doremalen N, et al. A novel coronavirus emerging in China — key questions for impact assessment. N Engl J Med 2020;382(8):692–694. DOI: 10.1056/NEJMp2000929
3. Su S, Wong G, Shi W, et al. Epidemiology, genetic recombination, and pathogenesis of coronaviruses. Trends Microbiol 2016;24(6):490–502. DOI: 10.1016/j.tim.2016.03.003
4. Ng OW, Tan YJ. Understanding bat SARS-like coronaviruses for the preparation of future coronavirus outbreaks — implications for coronavirus vaccine development. Hum Vaccin Immunother 2017;13(1):186–189. DOI: 10.1080/21645515.2016.1228500
5. Meyerowitz EA, Richterman A, Gandhi RT, et al. Transmission of SARS-CoV-2: a review of viral, host, and environmental factors. Ann Intern Med 2021;174(1):69–79. DOI: 10.7326/M20-5008
6. Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations [Internet]. World Health Organization; 2021. Available from https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions. [Last accessed August, 2024].
7. Parasher A. COVID-19: current understanding of its pathophysiology, clinical presentation and treatment. Postgrad Med J 2021;97(1147):312–320. DOI: 10.1136/postgradmedj-2020-138577
8. Pascarella G, Strumia A, Piliego C, et al. COVID-19 diagnosis and management: a comprehensive review. J Intern Med 2020;288(2):192–206. DOI: 10.1111/joim.13091
9. Arora N, Kumar HM. ‘The photographic negative of pulmonary oedema’ in COVID-19 pneumonia. Postgrad Med J 2021;97(1148):401. DOI: 10.1136/postgradmedj-2020-139265
10. Bhimraj A, Morgan RL, Shumaker AH, et al. IDSA guidelines on the treatment and management of patients with COVID-19. Infectious Diseases Society of America; 2023. Version 11.0.0. Available from https://www.idsociety.org/practice-guideline/covid-19-guideline-treatment-and-management/. [Last accessed August,2024].
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