In a recent study, researchers have highlighted the necessity for updated COVID-19 vaccine compositions due to the emergence of SARS-CoV-2 variants. The study also emphasizes the importance of double booster shots to counter immune imprinting induced by the ancestral strain.

The research, conducted on mouse models and human cohorts, focused on understanding the extent and dynamics of immune imprinting, particularly in relation to repeated Omicron stimulation. The findings shed light on potential strategies to address immune imprinting and enhance the antibody response.

Results from the mouse models indicated that single Omicron boosters had limited efficacy when using variants that differ antigenically from the ancestral strain, such as the XBB variant. However, the study demonstrated that a second Omicron booster could mitigate this concern and improve the antibody response.

Similarly, in humans, the research found that repeated Omicron infections could alleviate immune imprinting induced by the ancestral strain. This led to the development of broad neutralization responses in the plasma and nasal mucosa of vaccinated individuals. The study revealed that double Omicron exposure induced a significant proportion of matured Omicron-specific antibodies with distinct receptor-binding domain (RBD) epitopes compared to the antibodies produced by the ancestral strain vaccination.

Deep mutational scanning-based epitope characterization of 781 monoclonal antibodies targeting the receptor-binding domain (RBD) extracted from individuals with repeated Omicron infections provided valuable insights. Analysis of these antibodies demonstrated that double Omicron exposure restored the bias towards non-neutralizing epitopes that were observed in single Omicron exposures.

On the basis of the deep mutational scanning profiles, the researchers identified evolution hotspots of the XBB.1.5 RBD variant. These specific mutations were found to enhance the immune-evasion capability of XBB.1.5 while maintaining a high affinity for the ACE2 receptor.

Based on the study's findings, it is recommended that the ancestral strain component be abandoned when updating COVID-19 vaccines. Additionally, individuals who have not been previously exposed to the Omicron variant are advised to receive double updated vaccine boosters to enhance their immune response.

This research serves as a crucial reminder of the ongoing need to adapt COVID-19 vaccines in response to emerging variants. With the Omicron variant gaining prominence, updating vaccine compositions and implementing double booster strategies will be essential in effectively combating the virus and mitigating potential immune imprinting issues.

The study's findings provide valuable insights for public health authorities and vaccine developers as they work to combat the ongoing COVID-19 pandemic.