Madrid
Updated:18/05/2022 18:07h
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Unvaccinated individuals who have passed Covid-19 with the Ómicron strain are not effectively protected against other variants of SARS-CoV-2, such as Delta, according to a new article published in «Nature». However, Vaccinated people who were infected with Omicron are.
These results demonstrate that Omicron infection enhances pre-existing vaccine-induced immunity but, by itself, may not confer broad protection against non-Omicron variants in unvaccinated individuals.
The team of Melanie Ott from the Gladstone Institutes in San Francisco (USA) has analyzed SARS-CoV-2 infections caused by different subtypes, WA1, Delta and wild-type Omicron in a mouse model.
Thus, they have seen that infection by Ómicron was significantly milder and generated a reduced immune response compared to infection by WA1 and Delta.
The authors collected sera from mice seven days after infection and tested their neutralizing efficacy against WA1, Alpha, Beta, Delta and Omicron infections.
And the results showed that sera from Omicron-infected mice induced neutralization only against Omicron.
In contrast, sera from Delta-infected mice showed effective neutralization against WA1, Alpha, Beta, and Delta, and some neutralization against Omicron, and sera from WA1-infected mice showed effective neutralization against WA1 and Alpha, and some neutralization against Omicron. against Beta and Delta.
These results were replicated nine days after infection.
The authors confirmed that Omicron infection does not provide effective neutralization against other SARS-CoV-2 variants using sera from ten unvaccinated individuals who had recovered from Omicron infection.
As observed in mice, these sera showed effective neutralization only against the Omicron variant.
However, sera from vaccinated individuals with confirmed infection by advancement of Omicron or Delta showed effective neutralization against all variants.
These findings suggest that infections with Omicron or Delta after vaccination may boost existing immunity by causing a ‘hybrid immunity‘ against all variants and provide broad protection against infection.
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