scholarly journals Estimates of reduced vaccine effectiveness against hospitalization, infection, transmission and symptomatic disease of a new SARS-CoV-2 variant, Omicron (B.1.1.529), using neutralizing antibody titers

2021 ◽  
Author(s):  
Billy J Gardner ◽  
A. Marm Kilpatrick
Keyword(s):  
Neutralizing Antibodies ◽  
Immune Escape ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Vaccine Effectiveness ◽  
Vaccine Protection ◽  
Infection Transmission ◽  
Symptomatic Disease ◽  
Antibody Titers ◽  
Protection Against Infection

The emergence of the Omicron variant (B.1.1.529) of SARS-CoV-2 has raised concerns about how mutations in the spike protein might influence immune escape and vaccine protection against infection and disease, COVID-19. Initial estimates of immune escape measure neutralizing antibody titers, which have been shown to be a correlate of protection for COVID-19, but vary among studies. However, no studies have examined variation in vaccine effectiveness (VE) using estimated reductions in neutralizing antibody titers across virus variants. We quantified consistency in relative neutralizing antibody titers across studies. We then examined relationships between variant-specific reductions in neutralizing antibodies and protection against documented infection, symptomatic disease, and hospitalizations across variants and vaccines. We found considerable variation in variant-specific neutralizing antibody titers between studies, but within-study comparisons across variants were far more robust. There was insufficient data to estimate VE for a single vaccine across variants, especially for higher levels of immune evasion (>7-fold reductions in neutralizing antibody titers) observed with the Omicron variant (40-fold). Instead, we leveraged variation among both vaccines and virus variants to estimate VE - neutralizing antibody titer relationships across a 30 to 100-fold range of neutralizing antibody titers reduction. Omicron increased the risk of hospitalization four to five-fold and increased the risk of symptomatic disease seven to ten-fold for mRNA vaccinees, with similar relative effects for recently vaccinated, or individuals with waned antibody titers. Third doses restored titers and protection to levels similar to waned immunity against Delta. Overall, these analyses indicate that vaccine effectiveness against severe disease is significantly diminished for waned individuals, and protection against infection, symptomatic disease and transmission is nearly eliminated. However, third doses significantly ameliorate these reductions but only restore protection to levels equivalent to waned protection against the Delta variant. The invasion of Omicron is likely to result in widespread infection, and substantial hospitalizations unless widespread boosting of immunity occurs.

scholarly journals Third doses of COVID-19 vaccines reduce infection and transmission of SARS-CoV-2 and could prevent future surges in some populations

2021 ◽  
Author(s):  
Billy J Gardner ◽  
A. Marm Kilpatrick
Keyword(s):  
Vaccine Coverage ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Reproductive Number ◽  
Vaccine Protection ◽  
Contact Rates ◽  
Previous Infection ◽  
Antibody Titers ◽  
Protection Against Infection ◽  
The Impact

Background Vaccines have greatly reduced the impact of COVID-19 globally. Unfortunately, evidence indicates that immunity wanes following vaccination, especially with the Delta variant (B.1.617.2). Protection against severe disease and death remain high, but protection against milder disease and infection have dropped significantly. A third booster dose of two-dose vaccines has been approved in several countries to individuals at higher risk of severe disease to protect those individuals, but the benefit to boosting immunity in younger healthy individuals and the effects on transmission are less clear. Methods Here we use relationships between neutralizing antibody titers and vaccine protection against infection and transmission, combined with data on waning and boosting of neutralizing antibody titers to examine the impact of a third dose of the Pfizer vaccine on infection and transmission and its impact on the pathogen effective reproductive number Rt. Findings Eight months of waning reduced protection of the Pfizer vaccine against all infections from 80.0% (95% CI: 77% to 83%) to 60.4% (95% CI: 53% to 67%); a third dose (which increased neutralizing antibody titers 25.9- fold relative to levels after 8 months of waning) increased protection to 87.2% (95% CI: 83% to 91%). Increased protection against infection and transmission from third doses reduced Rt by 21% to 66% depending on vaccine coverage and previous infection and reduced Rt below 1 when vaccination coverage was high or contact rates were well below pre-pandemic levels. Interpretation A third dose of the Pfizer vaccine could reduce transmission of SARS-CoV-2, which would reduce infection in unvaccinated individuals and breakthrough infections in vaccinated individuals. While vaccination of unvaccinated individuals, especially in developing countries, would be more effective for reducing disease than providing a third dose to vaccinated individuals, the benefit of a third dose in reducing transmission is sizeable and increases with vaccine coverage and contact rates among individuals.

scholarly journals Titers of Neutralizing Antibodies against SARS-CoV-2 Are Independent of Symptoms of Non-Severe COVID-19 in Young Adults

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 284
Author(s):  
Hulda R. Jonsdottir ◽  
Michel Bielecki ◽  
Denise Siegrist ◽  
Thomas W. Buehrer ◽  
Roland Züst ◽  
...  
Keyword(s):  
Young Adults ◽  
Neutralizing Antibodies ◽  
Severe Disease ◽  
Humoral Response ◽  
Neutralizing Antibody ◽  
Neutralization Assay ◽  
Asymptomatic Infection ◽  
Homogeneous Population ◽  
Humoral Immune ◽  
Antibody Titers

Neutralizing antibodies are an important part of the humoral immune response to SARS-CoV-2. It is currently unclear to what extent such antibodies are produced after non-severe disease or asymptomatic infection. We studied a cluster of SARS-CoV-2 infections among a homogeneous population of 332 predominantly male Swiss soldiers and determined the neutralizing antibody response with a serum neutralization assay using a recombinant SARS-CoV-2-GFP. All patients with non-severe COVID-19 showed a swift humoral response within two weeks after the onset of symptoms, which remained stable for the duration of the study. One month after the outbreak, titers in COVID-19 convalescents did not differ from the titers of asymptomatically infected individuals. Furthermore, symptoms of COVID-19 did not correlate with neutralizing antibody titers. Therefore, we conclude that asymptomatic infection can induce the same humoral immunity as non-severe COVID-19 in young adults.

scholarly journals CoV-RBD121-NP Vaccine Candidate Protects against Symptomatic Disease Following SARS-CoV-2 Challenge in K18-hACE2 Mice and Induces Protective Responses That Prevent COVID-19-Associated Immunopathology

Vaccines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1346
Author(s):  
Jennifer K. DeMarco ◽  
Joshua M. Royal ◽  
William E. Severson ◽  
Jon D. Gabbard ◽  
Steve Hume ◽  
...  
Keyword(s):  
Antibody Response ◽  
Neutralizing Antibodies ◽  
Potential Role ◽  
Vaccine Candidate ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Antibody Responses ◽  
Receptor Binding Domain ◽  
Symptomatic Disease ◽  
Human Igg1

We developed a SARS-CoV-2 vaccine candidate (CoV-RBD121-NP) comprised of a tobacco mosaic virus-like nanoparticle conjugated to the receptor-binding domain of the spike glycoprotein of SARS-CoV-2 fused to a human IgG1 Fc domain. CoV-RBD121-NP elicits strong antibody responses in C57BL/6 mice and is stable for up to 12 months at 2–8 or 22–28 °C. Here, we showed that this vaccine induces a strong neutralizing antibody response in K18-hACE2 mice. Furthermore, we demonstrated that immunization protects mice from virus-associated mortality and symptomatic disease. Our data indicated that a sufficient pre-existing pool of neutralizing antibodies is required to restrict SARS-CoV-2 replication upon exposure and prevent induction of inflammatory mediators associated with severe disease. Finally, we identified a potential role for CXCL5 as a protective cytokine in SARS-CoV-2 infection. Our results suggested that disruption of the CXCL5 and CXCL1/2 axis may be important early components of the inflammatory dysregulation that is characteristic of severe cases of COVID-19.

scholarly journals Neutralizing antibody titers against dengue virus correlate with protection from symptomatic infection in a longitudinal cohort

2016 ◽  
Vol 113 (3) ◽  
pp. 728-733 ◽  
Author(s):  
Leah C. Katzelnick ◽  
Magelda Montoya ◽  
Lionel Gresh ◽  
Angel Balmaseda ◽  
Eva Harris
Keyword(s):  
Dengue Virus ◽  
Neutralizing Antibodies ◽  
Secondary Infection ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Denv Infection ◽  
Severe Dengue ◽  
Symptomatic Infection ◽  
Denv Serotypes ◽  
Antibody Titers

The four dengue virus serotypes (DENV1–4) are mosquito-borne flaviviruses that infect ∼390 million people annually; up to 100 million infections are symptomatic, and 500,000 cases progress to severe disease. Exposure to a heterologous DENV serotype, the specific infecting DENV strains, and the interval of time between infections, as well as age, ethnicity, genetic polymorphisms, and comorbidities of the host, are all risk factors for severe dengue. In contrast, neutralizing antibodies (NAbs) are thought to provide long-lived protection against symptomatic infection and severe dengue. The objective of dengue vaccines is to provide balanced protection against all DENV serotypes simultaneously. However, the association between homotypic and heterotypic NAb titers and protection against symptomatic infection remains poorly understood. Here, we demonstrate that the titer of preinfection cross-reactive NAbs correlates with reduced likelihood of symptomatic secondary infection in a longitudinal pediatric dengue cohort in Nicaragua. The protective effect of NAb titers on infection outcome remained significant when controlled for age, number of years between infections, and epidemic force, as well as with relaxed or more stringent criteria for defining inapparent DENV infections. Further, individuals with higher NAb titers immediately after primary infection had delayed symptomatic infections compared with those with lower titers. However, overall NAb titers increased modestly in magnitude and remained serotype cross-reactive in the years between infections, possibly due to reexposure. These findings establish that anti-DENV NAb titers correlate with reduced probability of symptomatic DENV infection and provide insights into longitudinal characteristics of antibody-mediated immunity to DENV in an endemic setting.

scholarly journals Dynamics of neutralizing antibody titers in the months after SARS-CoV-2 infection

2020 ◽  
Author(s):  
Katharine HD Crawford ◽  
Adam S Dingens ◽  
Rachel Eguia ◽  
Caitlin R Wolf ◽  
Naomi Wilcox ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Neutralizing Antibodies ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Spike Protein ◽  
Early Immune Response ◽  
Antibody Titers ◽  
Antibody Levels ◽  
Time Frames ◽  
Initial Peak

Most individuals infected with SARS-CoV-2 develop neutralizing antibodies that target the viral spike protein. Here we quantify how levels of these antibodies change in the months following SARS-CoV-2 infection by examining longitudinal samples collected between ≈30 and 152 days post-symptom onset from a prospective cohort of 34 recovered individuals with asymptomatic, mild, or moderate-severe disease. Neutralizing antibody titers declined an average of about four-fold from one to four months post-symptom onset. Importantly, our data are consistent with the expected early immune response to viral infection, where an initial peak in antibody levels is followed by a decline to a lower plateau. Additional studies of long-lived B-cells and antibody titers over longer time frames are necessary to determine the durability of immunity to SARS-CoV-2.

scholarly journals Dynamics of Neutralizing Antibody Titers in the Months After Severe Acute Respiratory Syndrome Coronavirus 2 Infection

2020 ◽  
Author(s):  
Katharine H D Crawford ◽  
Adam S Dingens ◽  
Rachel Eguia ◽  
Caitlin R Wolf ◽  
Naomi Wilcox ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Symptom Onset ◽  
Neutralizing Antibodies ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Spike Protein ◽  
Antibody Titers ◽  
Antibody Levels ◽  
Time Frames ◽  
Initial Peak

Abstract Most individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop neutralizing antibodies that target the viral spike protein. In this study, we quantified how levels of these antibodies change in the months after SARS-CoV-2 infection by examining longitudinal samples collected approximately 30–152 days after symptom onset from a prospective cohort of 32 recovered individuals with asymptomatic, mild, or moderate-severe disease. Neutralizing antibody titers declined an average of about 4-fold from 1 to 4 months after symptom onset. This decline in neutralizing antibody titers was accompanied by a decline in total antibodies capable of binding the viral spike protein or its receptor-binding domain. Importantly, our data are consistent with the expected early immune response to viral infection, where an initial peak in antibody levels is followed by a decline to a lower plateau. Additional studies of long-lived B cells and antibody titers over longer time frames are necessary to determine the durability of immunity to SARS-CoV-2.

scholarly journals Neutralization of the emerging SARS-CoV-2 variant Lambda by antibodies elicited by inactivated virus and mRNA vaccines

2021 ◽  
Author(s):  
Mónica Acevedo ◽  
Luis Alonso-Palomares ◽  
Marco Montes de Oca ◽  
Andrés Bustamante ◽  
Aldo Gaggero ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Immune Escape ◽  
Neutralizing Antibody ◽  
Neutralization Capacity ◽  
Antigenic Sites ◽  
Antibody Titers ◽  
Different Levels

Abstract Here, we used pseudotyped viruses to characterize the neutralization capacity of antibodies elicited by the CoronaVac and BNT162b2 vaccines against the emerging variant of interest Lambda. We observed that BNT162b2 elicits higher neutralizing antibody titers than CoronaVac, ranging from 5.8-fold for the ancestral spike to 9.4-fold for the Lambda variant. Neutralization against D614G, Alpha, Gamma, and Lambda variants was reduced between 1.78 to 3.05-fold for CoronaVac and 1.10 to 1.87-fold for BNT162b2. Structural analyses of the Lambda spike show significant changes in antigenic sites including the 246–252 deletion in an antigenic supersite at the NTD loop and, L452Q/F490S within the RBD that may account for immune escape. Our analysis of pseudotyped viruses also suggests increased infectivity driven by the Lambda spike. Together, our data indicate that inactivated virus and mRNA vaccines elicit different levels of neutralizing antibodies with different potency to neutralize SARS-CoV-2 variants, including the emergent variant Lambda.

scholarly journals Reduced levels of convalescent neutralizing antibodies against SARS-CoV-2 B.1+L249S+E484K lineage

2021 ◽  
Author(s):  
Diego Alejandro Alvarez Diaz ◽  
Katherine Laiton Donato ◽  
Orlando Alfredo Torres Garcia ◽  
Hector Alejandro Ruiz Moreno ◽  
Carlos E Franco Munoz ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Immune Escape ◽  
Natural Infection ◽  
Neutralizing Antibody ◽  
Epidemiological Data ◽  
Laboratory Characterization ◽  
Previous Infection ◽  
Surveillance Programs ◽  
Antibody Titers ◽  
Study Support

The E484K mutation at the SARS-CoV-2 Spike protein emerged independently in different variants around the world, probably as part of the ongoing adaptation of the virus to the human host, and has been widely associated with immune escape from neutralizing antibodies generated during previous infection or vaccination. In this work, the B.1+L249S+E484K lineage was isolated along with A.1, B.1.420 and B.1.111 SARS-CoV-2 lineages without the E484K mutation and the neutralizing titer of convalescent sera was compared using microneutralization assays. While no significant differences in the neutralizing antibody titers were found between A1 and B lineages without the E484K mutation, the neutralizing titers against B.1+L249S+E484K were 1.5, 1.9, 2.1, and 1.3-fold lower than against A.1, B.1.420, B.1.111-I, and B.1.111-II, respectively. However, molecular epidemiological data indicate that there is no increase in the transmissibility rate associated with this new lineage. Hence, although the evidence provided in this study support a Variant of Interest Status (VOI) for the B1+L249S+E484K lineage, enhanced laboratory characterization of this particular lineage and other emerging lineages with the E484K mutation should be carried out in individuals with immunity acquired by natural infection and vaccination. This study accentuated the capability of new variants with the E484K mutation to be resistant to neutralization by humoral immunity, and therefore the need to intensify surveillance programs.

scholarly journals Neutralizing Antibody Therapeutics for COVID-19

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 628
Author(s):  
Aeron C. Hurt ◽  
Adam K. Wheatley
Keyword(s):  
High Risk ◽  
Neutralizing Antibodies ◽  
Controlled Trial ◽  
Antiviral Treatment ◽  
Severe Disease ◽  
Neutralizing Antibody ◽  
Supplemental Oxygen ◽  
European Medicines Agency ◽  
Global Public Health ◽  
Public Health Burden

The emergence of SARS-CoV-2 and subsequent COVID-19 pandemic has resulted in a significant global public health burden, leading to an urgent need for effective therapeutic strategies. In this article, we review the role of SARS-CoV-2 neutralizing antibodies (nAbs) in the clinical management of COVID-19 and provide an overview of recent randomized controlled trial data evaluating nAbs in the ambulatory, hospitalized and prophylaxis settings. Two nAb cocktails (casirivimab/imdevimab and bamlanivimab/etesevimab) and one nAb monotherapy (bamlanivimab) have been granted Emergency Use Authorization by the US Food and Drug Administration for the treatment of ambulatory patients who have a high risk of progressing to severe disease, and the European Medicines Agency has similarly recommended both cocktails and bamlanivimab monotherapy for use in COVID-19 patients who do not require supplemental oxygen and who are at high risk of progressing to severe COVID-19. Efficacy of nAbs in hospitalized patients with COVID-19 has been varied, potentially highlighting the challenges of antiviral treatment in patients who have already progressed to severe disease. However, early data suggest a promising prophylactic role for nAbs in providing effective COVID-19 protection. We also review the risk of treatment-emergent antiviral resistant “escape” mutants and strategies to minimize their occurrence, discuss the susceptibility of newly emerging SARS-COV-2 variants to nAbs, as well as explore administration challenges and ways to improve patient access.

scholarly journals Durability of Response to a Third BNT162b2 Vaccine in Adults ≥60 Years

2021 ◽  
Author(s):  
Noa Eliakim Raz ◽  
Amos Stemmer ◽  
Yaara Leibovici-Weissman ◽  
Asaf Ness ◽  
Muhammad Awwad ◽  
...  
Keyword(s):  
Adverse Events ◽  
Neutralizing Antibodies ◽  
Multivariable Analysis ◽  
Vaccine Dose ◽  
Neutralizing Antibody ◽  
Clinical Frailty Scale ◽  
Younger Adults ◽  
The Third ◽  
Antibody Titers ◽  
Level 2

BACKGROUND Age and frailty are strong predictors of COVID-19 mortality. After the second BNT162b2 dose, immunity wanes faster in older (≥65 years) versus younger adults. The durability of response after the third vaccine is unclear. METHODS This prospective cohort study included healthcare workers/family members ≥60 years who received a third BNT162b2 dose. Blood samples were drawn immediately before (T0), 10-19 (T1), and 74-103 (T2) days after the third dose. Antispike IgG titers were determined using a commercial assay, seropositivity was defined as ≥50 AU/mL. Neutralizing antibody titers were determined at T2. Adverse events, COVID-19 infections, and clinical frailty scale (CFS) levels were documented. RESULTS The analysis included 97 participants (median age, 70 years [IQR, 66-74], 61% women, 58% CFS level 2). IgG titers, which increased significantly from T0 to T1 (medians, 440 AU/mL [IQR, 294-923] and 25,429 [14,203-36,114] AU/mL, respectively; P<0.001), decreased significantly by T2, but all remained seropositive (median, 8,306 AU/mL [IQR, 4595-14,701], P<0.001 vs T1). In a multivariable analysis, only time from the first vaccine was significantly associated with lower IgG levels at T2 (P=0.004). At T2, 60 patients were evaluated for neutralizing antibodies; all were seropositive (median, 1,294 antibody titer [IQR, 848-2,072]). Neutralizing antibody and antispike IgG levels were correlated (R=0.6, P<0.001). No major adverse events or COVID-19 infections were reported. CONCLUSIONS Antispike IgG and neutralizing antibodies levels remain adequate 3 months after the third BNT162b2 vaccine in healthy adults ≥60 years, although the decline in IgG is concerning. A third vaccine dose in this population should be top priority.

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