Studies compare delta breakthrough infections against Omicron with COVID booster-induced protection

In a recent survey published on the preprint server medRxiv *, Researchers have shown the ability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta breakthrough infection and the ability to neutralize antibodies induced by a third booster of the coronavirus disease 2019 (COVID-19) vaccine. A variant compared to SARS-CoV-2 Omicron.

Here, researchers observe that symptomatic delta breakthrough infections are as effective as a third booster vaccine dose in inducing cross.Neutralizing antibody For SARS-CoV-2 delta and Omicron variants.

study: SARS-CoV-2 breakthrough infection in delta-dominant epidemics and neutralizing antibodies against Omicron compared to a third dose of BNT162b2: consistent analysis. Image Credit: MK photograp55 / Shutterstock.com

Background

Current COVID-19 vaccines are associated with high efficacy in reducing the risk of SARS-CoV-2 infection, symptomatic COVID-19, hospitalization, and death. However, millions of breakthrough infections have been reported worldwide due to the decline in vaccine efficacy over time and the emergence of SARS-CoV-2 mutants with high antigenic escape. As a result, a third booster immunization of the COVID-19 vaccine is recommended to maintain protection against these mutants.

Previous reports indicate that the anti-SARS-CoV-2 immune response of individuals who received two COVID-19 vaccinations and experienced a delta breakthrough infection was observed in people who received three vaccinations. It has been suggested that they are similar.

About research

Current research involves healthcare professionals from the National Center for Global Health and Medical Research. All participants participated in the June 2021 baseline serological study and the December 2021 follow-up study.

A total of 836 inexperienced participants were identified at baseline with two doses of the messenger ribonucleic acid (mRNA) vaccine BNT162b2 (Pfizer / BioNTech). Of them, 11 were confirmed to have a delta breakthrough infection at follow-up.

In the current study, scientists are evaluating anti-wild SARS-CoV-2, anti-delta, and anti-omicron neutralization. Effectiveness of Antibodies in double-vaccinated individuals infected with the delta variant after vaccination. This neutralizing effect was then compared to that observed in individuals who did not have the infection, with or without booster vaccination (third dose). In each case, infection-free controls were randomly selected from participants with or without a third booster vaccination.

Important findings

All study participants had comparable SARS-CoV-2 spike-binding antibodies at baseline. The highest levels of neutralizing antibodies were observed against the wild-type SARS-CoV-2 strain, followed by delta variants. None of the participants had a detectable neutralizing titer against the Omicron mutant at baseline.

Neutralizing titer for SARS-CoV-2 strain

At follow-up, induction of 4.1-fold and 10.9-fold induction titers against wild-type SARS-CoV-2 strains was achieved among participants who experienced delta breakthrough infection or who received booster immunization, respectively. It was observed. In contrast, the neutralizing titer became undetectable in inexperienced participants who received two vaccinations.

Regarding the neutralizing titers for delta mutants at follow-up, 5.5-fold and 13.8-fold inductions were observed between participants with breakthrough infection and those with booster vaccination, respectively. In contrast, infectious participants who received two vaccinations were observed to have a 2.8-fold reduction in delta neutralizing titer.

All study participants who received the booster vaccine, and two-thirds of those with breakthrough infections, showed detectable titers for the SARS-CoV-2 omicron variant at follow-up.

Approximately one-third reduced anti-SARS-CoV-2 spike antibody in participants who experienced breakthrough infection with the SARS-CoV-2 delta variant compared to the levels observed in boosted participants. The titer was observed.

Symptomatic and asymptomatic infections

Participants who reported symptomatic breakthrough infections showed 3.8-17.7 times the neutralizing titer for wild-type, delta, and omicron strains at follow-up. In contrast, participants with asymptomatic breakthrough infections showed a 3.1-fold reduction in anti-wild-type titers at follow-up, with no induction of anti-delta and anti-Omicron titers.

Omicron vs. Delta Neutralizing Titer

Considering all participants, at baseline, 85% and 89% showed detectable neutralization titers for wild-type and delta strains, respectively. In contrast, anti-Omicron neutralizing titers could not be detected in all participants. Overall, the anti-delta neutralizing titer was 1.6 times lower than the anti-wild type titer.

Compared to anti-wild type and anti-delta neutralizing titers, anti-omnionic titers were significantly lower in participants with breakthrough delta infections and those receiving booster immune vaccines.

Neutralization and spike antibody titer changes in individuals who experienced breakthrough infections, received booster vaccines, or did not receive booster during follow-up. The NAb titer against the original Wuhan stock is shown (A), Delta variant (B), And Omicron BA.1 variant (C) 50% focus reduction neutralization test (FRNT)₅₀) Use serum at baseline and follow-up. Anti-spiky antibody titers measured with Abbott’s reagent are also shown (D) And Roche reagents (E) At baseline and follow-up. The boxplot shows the median, interquartile range, and full range. The dashed horizontal line shows the LOD in the current analysis (NT).₅₀<40 at FRNT₅₀ U / mL> 25000 in the Roche assay).

The magnification variation is an estimated ratio of the geometric mean of antibody titers based on the GEE model (ns: not significant; * P <0.05; ** P <0.01; *** P <0.001). Abbreviation: AU, arbitrary unit. B, baseline; F, follow-up; GEE, generalized estimation equation; LOD, detection limit; NT₅₀50% neutralization titerSARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2.

Neutralizing and spike antibody titers, symptomatic and asymptomatic breakthrough infections after 3 vaccinations. The NAb titer against the original Wuhan stock is shown (A), Delta variant (B), And Omicron BA.1 variant (C) 50% focus reduction neutralization test (FRNT)₅₀) Use serum during follow-up. Anti-spiky antibody titers measured with Abbott’s reagent are also shown (D) And Roche reagents (E) Use serum during follow-up.

All patients with the infection confirmed by PCR were symptomatic (n = 7), but all patients who were sero-positive with either anti-SARS-CoV-2 nucleocapsid protein assay (Abbott or Roche assay) at follow-up. It was asymptomatic (n = 4). The bar indicates the geometric mean titer and the I-shaped bar indicates its geometric standard deviation.The dashed horizontal line indicates the FRNT LOD.₅₀ (NT₅₀<40）および現在の分析におけるロシュアッセイ（U / mL> 25000). Statistical significance was determined by a multiple comparison test of Krascal Wallis and Dan (ns: not significant; * P <0.05; ** P <0.01; *** P <0.001).

Abbreviation: AU, arbitrary unit. COVID-19, Coronavirus Disease 2019; LOD, Detection Limit; NT50, 50% Neutralizing Potency; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2.

Implications

Current studies show that both symptomatic delta breakthrough infections and triple-dose COVID-19 vaccination regimens have neutralizing antibody potency against wild SARS-CoV-2 strains and both delta and omicron variants. It emphasizes that it has the same effect in inducing the value.

Given the much lower neutralizing titers for antigenic escape variants such as Omicron, scientists recommend implementing infection control measures, regardless of population-level vaccination rates.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they have not been peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.