In a recent study published in the Frontiers Public Health, researchers studied the characteristics and markers associated with coronavirus disease 2019 (COVID-19) disease progression in hospitalized adults.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain (RBD) that comes in contact with the angiotensin converting enzyme-2 (ACE-2) protein is expressed on a variety of host cells and appears to be uniquely affected by multiple genetic abnormalities in the SARS-CoV-2 Omicron spike (S) protein, especially in the S1 and S2 regions. The Omicron variant includes important subvariants, such as B.1.1.529, BA.1, BA.1.1, BA.2, BA.3, BA.4, BA.5, and BA.7. Notably, BA.1 is one of the few dominant mutants that has supposedly managed to avoid the neutralizing antibodies elicited by COVID-19 vaccination.
The rise in Omicron BA.2 infections shows that the variant has a selection advantage over BA.1 in terms of infection rates. Despite claims that BA.1 and BA.2 have a number of shared mutations, each variant has different mutations. Although virus variants can change how an illness presents and its pathogenesis manifests, more research is required to establish whether the viral load (VL) of SARS-CoV-2 in the respiratory tract can predict disease manifestations.
About the study
In the present study, researchers conducted a case-control study to determine which clinical, demographic, clinical history and virological variables may accurately predict COVID-19 disease progression in hospitalized individuals.
From December 2021 to January 2022, 287 persons with COVID-19-related illnesses were hospitalized at the Government Corona Hospital in Chennai, India, and were recruited for the case-control study. The participants had to meet the age requirement of 18 years or older to be included. Participants' nasopharyngeal swabs were obtained for a standard COVID-19 diagnostic. The demographic data included information like age, sex, vaccination status, history of SARS-CoV-2 infection, COVID-19 symptoms and signs, type of vaccine received, comorbidities, and treatment outcomes.
Clinical Guidance for Management of Adult COVID-19 Patients from the Ministry of Health and Family Welfare, Government of India, served as the basis for the clinical classification of the study participants. According to the same, if a person experienced upper respiratory symptoms and/or fever but not shortness of breath or hypoxia, they were considered to have mild COVID-19.
Patients with moderate disease reported either one of the following symptoms, which required hospitalization: a respiratory rate of 24 or less per minute, breathlessness, or saturation of peripheral oxygen (SpO2) between 90% and 93% on room air. If a participant displayed one or more of these COVID-19 manifestations, they were considered to have a severe or critical illness: breathlessness or an SPO2 of less than 90% in room air, which needed admission to an intensive care units (ICU) or high dependency units (HDU). Fresh ribonucleic acid (RNA) was isolated from the primary sample source for all samples chosen for sequencing.
The current study enrolled 287 SARS-CoV-2-infected individuals who were being treated in a hospital for COVID-19. The range of ages was 64 to 80 years, with 73 being the median age and 68.6% of the population being male. Almost 63% of the patients in this cohort received AZD1222, while 37.2% received BBV152. These vaccine recipients showed a wide variety of symptoms, with 6.3%, 30.3%, 47.4%, and 16% experiencing asymptomatic, mild, moderate, and severe COVID-19. Omicron BA.1, Omicron BA.1.1, Omicron BA.2, and Delta B.1.617.2 variants accounted for 17.4%, 57.5%, 21.9%, and 3% of the identified variants.
The alterations in the spike areas of the BA.1, BA.1.1, BA.2, and B.1.617.2 variants were found using sequence analysis. The team noted that BA.1 and BA.1.1 had 33 and 30 mutation sites, respectively. Furthermore, BA.2 reported 29 mutation sites, while B.1.617.2 had eight. The BA.2 and the Delta variant B.1.617.2 did not have the significant mutation del69/70 frequently reported in BA.1.1 and BA.1.1.529. Mutations such as T19I, L24S, P25del, P26del, A27S, V213G, T376A, D405N, and R408S were specific to BA.2.
The findings revealed a significant relationship between the SARS-CoV-2 viral load and an elevated risk of developing severe illness, admission to an HDU or ICU, need for mechanical ventilation, and mortality. Every 1 log increase in viral load was linked to an increased risk of death, HDU/ICU admission, ventilator use, and severe illness. An increased likelihood of being asymptomatic, mild/moderately sick, and recovering was considerably related to vaccination.
Overall, the study findings showed that the low SARS-CoV-2 viral load noted among COVID-19-vaccinated individuals infected with the Delta B.1.617.2 and the Omicron BA.1 variant but not with the BA.1.1 and A.2 variants may be an indication that the more recent variants are likely to evade the host's immune responses induced by the vaccine.