A new study by scientists from Kent University, Great Britain, suggests that infection with the SARS-CoV-2 version of the Omicron virus can provide some protection against seasonal influenza.
The first case of the Omicron option was discovered in Botswana on 9 November 2021; on 26 November 2021, the World Health Organization classified it as an option of concern; the mutations it bears make it more contagious and resistant to vaccine immunity, but are less likely to cause severe forms of COVID-19.
It was shown that the severity of the disease depended to a large extent on interferon virus-induced signaling. The latest results from cell lines suggested that BA.1 would induce greater interferon production than the Delta version before it. Therefore, a group of researchers had sought to study the replication of Delta, BA.1 and BA.5, compare interferon signals in each case, and monitor the impact of infection in one of its versions on the replication of another virus, H1N1.
More sustainable response to interferons
At first, scientists infected primary epithelial cells of human bronchics and primary human monocytes with Delta and BA.1. Cells treated with a simple physiological solution without the virus served as a test sample. As expected, BA.1 showed a faster kinetic replication than Delta in cell cultures. Similarly, BA.1 caused a stronger interferon response than Delta. "," researchers write in their prescient article.
Short-term reactions to type I interferon suppress the replication of respiratory virus on epithelial respiratory barriers and prevent excessive inflammation, explain the team. Therefore, the type I and III reactions observed here explain why Omicron is less pathogenic than other SARS-Cov-2 options.
An option to prevent the replication of the influenza virus
The researchers then conducted another experiment with the same cells, infecting them two days later with the H1N1 virus.
A day later, they measured the H1N1 load in all groups of cells, and they found that cells previously infected with Delta, as well as control cells, had a very high viral load, which suggests that the H1N1 virus was replicated very quickly. ", concluded by researchers.
A similar experiment with cells infected with BA.5 showed a similar interferon response, which caused the same effect: both of the Omicron subvariants were inhibiting the replication of H1N1.
These results fully reflect the level of morbidity observed during the pandemic. "", researchers note in their work, and these patterns can also be linked to the fact that people are more cautious and protect themselves from winter infections.
A better understanding of how different SARS-CoV-2 options cause different immune responses can help researchers to determine the impact of potential new options more quickly. However, as the authors of the study point out, these results do not mean that it is useful to deliberately infect COVID-19 to protect against influenza.