Highly effective defenses towards Omicron reinfection

So far, the continuing coronavirus illness 2019 (COVID-19) pandemic, brought on by the extreme acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has claimed greater than 6.94 million lives worldwide.

Examine: Humoral immune response to omicron an infection in long-term Wuhan-Hu-1-imprinted inhabitants. Picture Credit score: visualstock / Shutterstock.com

*Vital discover: Analysis Sq. publishes preliminary scientific experiences that aren’t peer-reviewed and, due to this fact, shouldn’t be considered conclusive, information medical observe/health-related habits, or handled as established data.


In distinction to prior suggestions, the current World Well being Group (WHO) steering indicated no want for annual booster COVID-19 vaccination for low-risk populations. This up to date WHO steering has triggered a debate on the effectiveness of normal booster vaccination, notably due to the shortage of spectacular serum neutralization towards SARS-CoV-2 Omicron sub-variants.

The abrupt withdrawal of COVID-19 booster suggestions may be on account of incomplete proof relating to the persistence and effectiveness of pure infection-elicited immune safety towards re-infection brought on by rising variants with totally different antigenic traits.

Nearly all of research have indicated that prior an infection of Wuhan-Hu-1(WH1), which is the ancestral SARS-CoV-2 pressure, and WH1-based vaccination have weakened humoral immune responses to Oubsequent omicron an infection. These findings are per immune imprinting in influenza virus an infection.

Antigenic cartography research have demonstrated that antigenic distances between SARS-CoV-2 variants and Omicron sub-variants had been solely of 103-fold change in neutralization titer ranges. Thus, as in comparison with influenza an infection, SARS-CoV-2 an infection manifests smaller imprinting results.

Many of the world inhabitants was uncovered to SARS-CoV-2 antigens by WH1-based vaccines. In consequence, a brand new research underneath evaluate at Nature Portfolio and at present posted to the Analysis Sq. preprint server evaluates the results of long-term WH1 imprinting on the humoral immune response to an antigenically distant SARS-CoV-2 variant to find out the maximal imprinting results within the present SARS-CoV-2 variant panorama. 

In regards to the research

The Hubei province of China, which was the principle epicenter of the primary COVID-19 outbreak on the planet, efficiently prevented all pre-Omicron variants because of the implementation of strict public well being measures. Most individuals in Hubei had been vaccinated with a number of rounds of WH1-based COVID-19 vaccines; due to this fact, the vast majority of this inhabitants was completely WH1 imprinted.

Hubei skilled a population-wide Omicron outbreak in December 2022, with about 90% of the inhabitants contaminated by the BF.7 sub-variant and its derivates. Scientists took the chance of this sweeping outbreak to review immune imprinting in re-infected individuals.

The research cohort comprised WH1-infected individuals from Xiangyang Metropolis of Hubei province. Examine individuals reinfected with the Omicron variant supplied serum samples two months following the an infection. Among the individuals had been vaccinated with three doses of whole-inactivated virus (WIV) vaccines.

Serum samples collected from WH1-infected and triple-vaccinated individuals at three to 4 months earlier than Omicron an infection had been used as pre-infection controls.

Different cohorts from the identical area had been studied. One cohort included vaccinated individuals, whereas one other cohort contained unvaccinated individuals.

Pre- and post-Omicron an infection serum samples from the vaccinated and unvaccinated cohorts had been obtained. Importantly, all individuals didn’t have any historical past of immunological problems or had been underneath any medicine that might have an effect on the immune system.

Humoral immune responses had been measured utilizing pseudovirus neutralization assays, which had been based mostly on non-replicative vesicular stomatitis viruses (VSV) pseudotyped with spike proteins of WH1, Omicron BF.7, BQ.1.1, or XBB.1.5.

Examine findings

The present research used pre-and post-Omicron an infection sera from an completely WH1-imprinted inhabitants to find out long-term and lengthy antigenic distance immune imprinting on the humoral immune system. Primarily based on the pseudovirus neutralization assays, a rise in WH1 and Omicron sub-variants neutralization was noticed in WH1 imprinting as in comparison with naïve sera. 

Mechanistically, antibody suggestions restricted the magnitude of WH1 back-boost by antibody range enhancement. As well as, antigenic seniority triggered a fast upregulation of Omicron neutralization titers by recalling cross-reactive B-cells upon Omicron an infection.

Solely hybrid WH1 imprinting marginally diminished ahead neutralization breadth with out affecting the general neutralization titers after Omicron an infection.

Importantly, the imprinting results collectively elevated the safety ranges towards reinfection. Subsequently, it might be helpful to assist immune imprinting for humoral immunity.


The present research helps the WHO advice towards the COVID-19 booster vaccination in low-risk populations. In actual fact, the research findings strongly point out that Omicron an infection will confer immune safety in imprinted populations.

Nonetheless, SARS-CoV-2 variants with extra antigenic drift will induce immune safety much less successfully, regardless of the imprinting standing. The impact of immune imprinting will depend on the standard and amount of cross-reactive antibodies.

Taken collectively, long-term WH1 immune imprinting enhances the humoral immune response towards Omicron an infection with negligible adversarial results, thereby defending towards reinfection. In distinction to the findings of earlier research, the present research concluded that immune imprinting is a helpful mechanism.

*Vital discover: Analysis Sq. publishes preliminary scientific experiences that aren’t peer-reviewed and, due to this fact, shouldn’t be considered conclusive, information medical observe/health-related habits, or handled as established data.

Journal reference:

  • Preliminary scientific report.
    Liu, Y., Zhu, Y., Tang, L., et al. (2023) Humoral immune response to omicron an infection in long-term Wuhan-Hu-1-imprinted inhabitants. Analysis Sq.. doi:10.21203/rs.3.rs-3024491/v

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