Household transmission of SARS-CoV-2 Omicron variant of concern subvariants BA.1 and BA.2 in Denmark

Lyngse, Frederik Plesner; Kirkeby, Carsten; Denwood, Matthew; Christiansen, Lasse Engbo; Mølbak, Kåre; Møller, Camilla Holten; Skov, Robert; Krause, Tyra Grove; Rasmussen, Morten; Sieber, Raphael N.; Johannesen, Thor Bech; Lillebæk, Troels; Fonager, Jannik; Fomsgaard, Anders; Møller, Frederik Trier; Stegger, Marc; Overvad, Maria; Spieß, Katja; Mortensen, Laust Hvas

doi:10.1038/s41467-022-33498-0

Cited by 117 publications

(75 citation statements)

References 18 publications

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“…Nonetheless, the Omicron VOC has replaced the Delta VOC in the human population, and our study was not designed to address this question. Omicron is antigenically the most distant VOC (18), and recent studies suggest that Omicron variants can readily overcome immunity acquired from previous infection with earlier variants and vaccination (19)(20)(21)(22)(23). The rise in Omicron cases could be a combination of immune evasion, waning immunity, relaxation of coronavirus disease-related restrictions, and other factors that may affect transmission, such as reduced symptoms caused by Omicron, resulting in prolonged contact with other humans.…”

Section: Discussionmentioning

confidence: 99%

SARS-CoV-2 Omicron BA.1 and BA.2 are attenuated in rhesus macaques as compared to Delta

et al. 2022

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Since the emergence of SARS-CoV-2, five different variants of concern (VOCs) have been identified: Alpha, Beta, Gamma, Delta, and Omicron. Because of confounding factors in the human population, such as preexisting immunity, comparing severity of disease caused by different VOCs is challenging. Here, we investigate disease progression in the rhesus macaque model upon inoculation with the Delta, Omicron BA.1, and Omicron BA.2 VOCs. Disease severity in rhesus macaques inoculated with Omicron BA.1 or BA.2 was lower than those inoculated with Delta and resulted in significantly lower viral loads in nasal swabs, bronchial cytology brush samples, and lung tissue in rhesus macaques. Cytokines and chemokines were up-regulated in nasosorption samples of Delta animals compared to Omicron BA.1 and BA.2 animals. Overall, these data suggest that, in rhesus macaques, Omicron replicates to lower levels than the Delta VOC, resulting in reduced clinical disease.

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Section: Discussionmentioning

confidence: 99%

SARS-CoV-2 Omicron BA.1 and BA.2 are attenuated in rhesus macaques as compared to Delta

et al. 2022

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“…In the only available human challenge trial that was conducted with ancestral SARS-CoV-2, an initial infectious dose of 10 TCID 50 did not lead to an infection in 16 of 36 participants 29 . Other factors, such as symptoms, type of contact, protective measures, vaccination status and other host factors may have an additionally strong effect on transmission [128][129][130][131][132][133] .…”

Section: Influence Of Viral Load On Transmissionmentioning

confidence: 99%

SARS-CoV-2 viral load and shedding kinetics

2022

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SARS-CoV-2 viral load and detection of infectious virus in the respiratory tract are the two key parameters for estimating infectiousness. As shedding of infectious virus is required for onward transmission, understanding shedding characteristics is relevant for public health interventions. Viral shedding is influenced by biological characteristics of the virus, host factors and pre-existing immunity (previous infection or vaccination) of the infected individual. Although the process of human-to-human transmission is multifactorial, viral load substantially contributed to human-to-human transmission, with higher viral load posing a greater risk for onward transmission. Emerging SARS-CoV-2 variants of concern have further complicated the picture of virus shedding. As underlying immunity in the population through previous infection, vaccination or a combination of both has rapidly increased on a global scale after almost 3 years of the pandemic, viral shedding patterns have become more distinct from those of ancestral SARS-CoV-2. Understanding the factors and mechanisms that influence infectious virus shedding and the period during which individuals infected with SARS-CoV-2 are contagious is crucial to guide public health measures and limit transmission. Furthermore, diagnostic tools to demonstrate the presence of infectious virus from routine diagnostic specimens are needed.

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“…Together, these data may explain the difference in infectivity among Omicron subvariants [25]. Furthermore, its immune-evasive actions may influence vaccine effects, but this does not enhance its potency of transmission among vaccinated patients [59].…”

Section: Omicron Ba 2 Transmissibility Pathogenicity and Severitymentioning

confidence: 98%

The emergence of SARS-CoV-2 Omicron subvariants: current situation and future trends

et al. 2022

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The SARS-CoV-2 Omicron variant (B.1.1.529) has been the most recent variant of concern (VOC) established by the World Health Organization (WHO). Because of its greater infectivity and immune evasion, this variant quickly became the dominant type of circulating SARS-CoV-2 worldwide. Our literature review thoroughly explains the current state of Omicron emergence, particularly by comparing different omicron subvariants, including BA.2, BA.1, and BA.3. Such elaboration would be based on structural variations, mutations, clinical manifestation, transmissibility, pathogenicity, and vaccination effectiveness. The most notable difference between the three subvariants is the insufficiency of deletion (Δ69-70) in the spike protein, which results in a lower detection rate of the spike (S) gene target known as (S) gene target failure (SGTF). Furthermore, BA.2 had a stronger affinity to the human Angiotensin-converting Enzyme (hACE2) receptor than other Omicron sub-lineages. Regarding the number of mutations, BA.1.1 has the most (40), followed by BA.1, BA.3, and BA.3 with 39, 34, and 31 mutations, respectively. In addition, BA.2 and BA.3 have greater transmissibility than other sub-lineages (BA.1 and BA.1.1). These characteristics are primarily responsible for Omicron's vast geographical spread and high contagiousness rates, particularly BA.2 sub-lineages.

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Household transmission of SARS-CoV-2 Omicron variant of concern subvariants BA.1 and BA.2 in Denmark

Cited by 117 publications

References 18 publications

SARS-CoV-2 Omicron BA.1 and BA.2 are attenuated in rhesus macaques as compared to Delta

SARS-CoV-2 Omicron BA.1 and BA.2 are attenuated in rhesus macaques as compared to Delta

SARS-CoV-2 viral load and shedding kinetics

The emergence of SARS-CoV-2 Omicron subvariants: current situation and future trends

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