The Delta and Omicron strains of coronavirus are the most widespread strains of concern around the globe.
Although the Delta strain is more likely to cause severe lung disease, the Omicron strain causes less severe disease and mainly upper respiratory symptoms.
A key question is whether the rapid spread of the Omicron strain[/B] can lead to mass immunization of the population against SARS-CoV-2 and the achievement of collective immunity can lead to the end of the pandemic.
Physicians from the Therapeutic Clinic of the Medical School of the National and Kapodistrian University of Athens Theodora Psaltopoulou, Yannis Danasis, Panos Malandrakis and Thanos Dimopoulos (Dean of the University of Athens) summarize the latest data from the pre-publication of R. K. Suryawanshi et al. on immunity after infection with the Omicron strain of SARS-CoV-2 in COVID-19 models.
What is true for the development of broad immunity against multiple strains
The researchers showed that Delta strain infection rather than Omicron strain infection leads to the development of broad immunity against multiple strains of SARS-CoV-2 in mice.
Although serum from mice healed after infection with the Omicron strain shows neutralizing ability only against Omicron, serum from mice healed after infection with the Delta strain shows neutralizing ability against both Delta and other strains of concern, including Omicron.
This was not the case for infection with the original Wuhan WA1 strain, although both WA1 and Delta generated a potent cytokine-mediated pro-inflammatory response. Moreover, both strains replicated to the same extent in the upper respiratory tract and lungs of infected mice, as well as in human airway organelles.
In contrast, the degree of viral replication in the lungs, the expression of pro-inflammatory cytokines and overall disease severity was significantly reduced with the Omicron strain.
In addition, the researchers observed that the serum of people who were vaccinated and subsequently became ill with either the Delta or Omicron strain showed cross-contamination with other strains of SARS-CoV-2.
In conclusion, the results of this study suggest that infection with the Omicron strain enhances preexisting immunity against multiple SARS-CoV-2 strains from COVID-19 vaccines, while by itself probably does not lead to cross-humoral immunity in unvaccinated individuals.
Source: in.gr
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