The researchers found that study findings converge on a consistent relationship between antibody levels and protection from COVID-19

In a recent study published in Emerging infectious diseasesIn this study, researchers describe factors associated with protection, protection thresholds, and immunosuppression in patients with the novel coronavirus 2019 (COVID-19).

Study: Interrelationships between protection, protection thresholds, and immune immobilization among subjects with SARS-CoV-2 infection.  Image credit: ktsdesign/Shutterstock
Stady: Correlations of protection, protection thresholds, and immune immobilization among subjects with SARS-CoV-2 infection. Image credit: ktsdesign/Shutterstock


Predict the future effectiveness Vaccines to determine the link between protection and immune response against asymptomatic severe acute respiratory syndrome viral 2 (SARS-CoV-2). This relationship could facilitate immunocorrelation, which could help approve new or revised immunizations based on immunogenicity data without the need for extensive Phase III studies.

Immunostaining is being used to license seasonal influenza vaccines in the United States and the European Union, and it reduces the time and cost required to manufacture vaccines. Furthermore, determining levels of immunity needed to protect against emerging SARS-CoV-2 variants will be useful for predicting infection immunity at the population level, guiding public health vaccines, and advancing policies.

Comparing studies on the limits of protection

There are six published estimates of the geometric mean caliber (GMT) for recipients of ribonucleic acid (mRNA)-1273 immunization, ranged from 247 IU/mL to 1404 IU/mL. Similarly, GMT estimates for ChAdOx1-vaccinated recipients ranged from 23 to 144 IU/mL. It is evident from the discrepancies observed in the studies that titer expression in international units was not sufficient to standardize between the different tests and to compare the protection thresholds reported in these investigations, likely due to differences in the assays themselves.

An alternative method for standardizing parity titers across studies was to assume that similar groups of vaccinated individuals should have similar titres. This normalization method allowed comparison of protection curves across several immunocorrelation investigations. The team matched the data based on the assumption that the average titer of ChAdOx1- or mRNA-1273-vaccinated individuals was the same between the Phase 1/2 and Phase 3 trials of each vaccine.

Using the mRNA-1273 penetration infection model as an example, the team observed that immunization with mRNA-1273 resulted in increased levels of neutralization but poor agreement was observed at low levels of neutralization. Also, the ChAdOx1 protection curve showed strong consistency with previous investigations in the superinfection study area for which equivalent data were available.

Despite the fundamentally diverse data, assays, and methodologies used to estimate the protection curves in each investigation, findings from the superinfection studies showed high agreement with the vaccine comparison model.

In addition, after alignment with each GMT immunization cohort, the baseline distribution of neutralizing antibody titres along with the protection curves associated with each trial can be used to predict the overall vaccine efficacy of existing vaccines. This strategy indicated good agreement between all models and the observed data.

using a protection curve

Predicting vaccine efficacy with immunostimulation

Regulators have stressed the need for immunosuppression research, which compares the development of new vaccines to the immunogenicity of older vaccines. In other words, vaccine makers must note the current vaccine that is suitable for comparison and assess the margins of superiority or non-inferiority in a randomized controlled trial.

Using a vaccine comparison model built from previous research, the team can assess the margins of superiority or non-inferiority of current vaccines that would result in more than 80% efficacy against SARS-CoV-2. If BNR162b2 or mRNA-1273 were used as comparator vaccines, a margin of non-inferiority of about 0.44-fold for mRNA-1273 GMT or 0.54-fold for mRNA-1273 GMT would lead to high confidence that the proposed vaccine has an efficacy of >80%.

Using ChAdOx1 as a comparison, the team determined that a margin of superiority of 2.6-fold GMT vs. ChAdOx1 vaccines would provide a relatively high confidence of more than 80% of vaccine efficacy. Notably, these margins are very consistent with the low 95% confidence intervals predicted by research on penetrating injuries. The consensus of these three papers strongly supported the use of margins of superiority or non-inferiority in future trials of immunosuppression.

Define individual protection thresholds

A second goal of investigating protective thresholds was to establish a prophylactic titer for therapeutic application, such as a blood test for a clinically meaningful antibody level that indicates whether a person has a greater chance of being well protected against COVID-19. It was evident from the protection curves that there was a gradient of risk across several equivalent titers.

In addition, the variance in between-run tests is often notable enough to determine uncertainty within the neutralization titer for a given blood sample which can lead to wide confidence ranges for an individual’s expected protection. High confidence intervals when calculating individual neutralization titers, together with inconsistencies between different serological tests, were major obstacles to the effective evaluation and prediction of neutralizing antibody titres among individual patients.


The results of the study showed that the different COVID-19 factors evaluated in the protection studies had high agreement. However, additional immune responses may play an important role in protecting against symptomatic to severe SARS-CoV-2 infection. Consistency across different investigations of an association neutralizing antibodies Effectiveness against COVID-19 could be important for planning future vaccine use, assessing population immunity, and minimizing the global consequences of the COVID-19 pandemic.

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