Covid-19: Antibody levels fall after second Pfizer dose, but protection against severe disease remains, studies indicate

Mahase, Elisabeth

doi:10.1136/bmj.n2481

Cited by 5 publications

(4 citation statements)

References 2 publications

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“…Special attention should be given to the

(k, c)

pair as it plays a central role in estimating the current numbers of recovered and vaccinated cases. We have opted for

(k, c)

values of (240, 60) and (180, 30) for recovered and vaccinated cases, respectively, based on analyses [43, 44]. These specific

(k, c)

choices showcase an inverse connection with the

ψ

and

v_{2}

rates, representing immunity termination rates for previously infected or vaccinated individuals.…”

Section: Discussionmentioning

confidence: 99%

“…We should emphasize that, for the generation of

Currentl y_{V_{t}}

, we subtract from the cumulative number of vaccinated cases (

Cumulativ e_{V_{t}}

) the inner product of weights and new vaccinated cases around time step

t - k

as the immunity of these individuals attenuates significantly after

k

days. For the recovered and vaccinated cases, we select

(k, c) = (240, 60)

and

(k, c) = (180,30)

, based on the meta‐analyses [43, 44], as the immunity from infection lasts primarily 240 ± 60 days and the antibodies generated from vaccination drop significantly after 180 ± 30 days. We note that the selected

(k, c)

pairs are closely related to the

ψ

and

v_{2}

rates of System (), which represent the immunity termination rates of a previously infected or vaccinated case, correspondingly.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

A stochastic particle extended SEIRS model with repeated vaccination: Application to real data of COVID‐19 in Italy

Papageorgiou,

Tsaklidis

2024

Math Methods in App Sciences

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The prediction of the evolution of epidemics plays an important role in limiting the transmissibility and the burdensome consequences of infectious diseases, which leads to the employment of mathematical modeling. In this paper, we propose a stochastic particle filtering extended SEIRS model with repeated vaccination and time‐dependent parameters, aiming to efficiently describe the demanding dynamics of time‐varying epidemics. The validity of our model is examined using daily records of COVID‐19 in Italy for a period of 525 days, revealing a notable capacity to uncover the hidden dynamics of the pandemic. The main findings include the estimation of asymptomatic cases, which is a well‐known feature of the current pandemic. Unlike other proposed models that employ extra compartments for asymptomatic cases, which force the estimation of this proportion and significantly increase the model's complexity, our approach leads to the evaluation of the hidden dynamics of COVID‐19 without additional computational burden. Other findings that confirm the model's appropriateness and robustness are its parameter evolution and the estimation of more ICU‐admitted cases compared to the official records during the most prevalent infection wave of January 2022, attributed to the intensified increase in admissions that may have led to full occupancy in ICUs. As the vast majority of datasets contain time series of total recovered and vaccinated cases, we propose a statistical algorithm to estimate the currently recovered and protected through vaccination cases. This necessity arises from the attenuation of antibodies after vaccination/infection and is necessary for long‐time interval predictions. Finally, we not only present a novel stochastic epidemiological model and test its efficiency but also investigate its mathematical properties, such as the existence and stability of epidemic equilibria, giving new insights to the literature. The latter provides additional details concerning the system's long‐term behavior, while the conclusions drawn from the index provide perspectives on the severity and future of the COVID‐19 pandemic.

show abstract

“…Special attention should be given to the

(k, c)

pair as it plays a central role in estimating the current numbers of recovered and vaccinated cases. We have opted for

(k, c)

values of (240, 60) and (180, 30) for recovered and vaccinated cases, respectively, based on analyses [43, 44]. These specific

(k, c)

choices showcase an inverse connection with the

ψ

and

v_{2}

rates, representing immunity termination rates for previously infected or vaccinated individuals.…”

Section: Discussionmentioning

confidence: 99%

“…We should emphasize that, for the generation of

Currentl y_{V_{t}}

, we subtract from the cumulative number of vaccinated cases (

Cumulativ e_{V_{t}}

) the inner product of weights and new vaccinated cases around time step

t - k

as the immunity of these individuals attenuates significantly after

k

days. For the recovered and vaccinated cases, we select

(k, c) = (240, 60)

and

(k, c) = (180,30)

(k, c)

pairs are closely related to the

ψ

and

v_{2}

rates of System (), which represent the immunity termination rates of a previously infected or vaccinated case, correspondingly.…”

Section: Methodsmentioning

confidence: 99%

A stochastic particle extended SEIRS model with repeated vaccination: Application to real data of COVID‐19 in Italy

Papageorgiou,

Tsaklidis

2024

Math Methods in App Sciences

View full text Add to dashboard Cite

show abstract

“…It seems clear that all the current COVID-19 vaccines have a drop of effectiveness against the emerging variants. Even though, Pfizer/BioNtech fully-vaccinated individuals induced at least borderline immune responses, with the drop of titers over time, the level of induced antibodies 24 and with the emergence of the different variants, it is recommended to administer a third shot of the vaccine 25 . The situation is worse with the inactivated virus vaccines, since they induce lower and quickly declining humoral immune responses 26 .…”

Section: Discussionmentioning

confidence: 99%

Development of an in-house quantitative ELISA for the evaluation of different Covid-19 vaccines in humans

Gdoura

Ghaloum

Hamida

et al. 2022

Sci Rep

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Reliable serological assays are needed to understand the real impact of COVID-19. In order to compare the efficiency of different COVID-19 vaccines used in the National Vaccination Program in Tunisia, we have developed a quantitative in-house ELISA. The ELISA is based on the ectodomain of the SARS-CoV-2 Spike Baculovirus recombinant protein. We used a panel of 145 COVID-19 RT-PCR positive serum samples and 116 pre-pandemic serum samples as a negative panel. The validation was carried out by comparison to four commercial techniques (Vidas SARS-CoV-2 IgG anti-RBD Biomérieux, Elecsys Anti-Nucleocapsid of SARS-CoV-2 Roche, cPass GenScript and the quantitative Elecsys Anti-RBD of SARS-CoV-2, Roche). For the evaluation of the National Vaccination campaign, we have included 115 recipients who received one of the approved vaccines. The qualitative performances of the developed ELISA gave 96% sensitivity, 97.5% specificity and 0.968 accuracy. For the evaluation of the different brand of vaccines in recipients not previously infected with SARS-CoV-2, it seems that mRNA vaccine of Pfizer/BioNTech has shown a higher efficacy compared to inactivated virus vaccines. COVID-19 convalescent individuals have generated poor antibody responses. Nevertheless, when they are vaccinated with any brand of the COVID-19 vaccines, many of them mounted an exponential increase of the induced immune responses, qualified as a “hybrid vigor immunity”. Our developed in-house ELISA seems to be very efficient in evaluating the effectiveness of anti-COVID-19 vaccination. Platforms based on mRNA vaccine are better performing than those based on inactivated virus.

show abstract

“…It seems undoubtable that all the current COVID-19 vaccines have a drop of effectiveness against the emerging variants. Even though, P zer/Biontech full-vaccinated individuals induced at least borderline immune responses, but with the drop of the titers over time the level of induced antibodies [25] and with the emergence of the different variants, it is recommended to administer a third shot of the vaccine [26]. The situation is still worse with the inactivated virus vaccines, since they induce lower and quickly declining humoral immune responses [27].…”

Section: Discussionmentioning

confidence: 99%

Development of an in-house Quantitative ELISA for the Evaluation of Different Covid-19 Vaccines in Human

Gdoura

Ghaloum

Hamida

et al. 2022

Preprint

View full text Add to dashboard Cite

Purpose: Reliable serological assays are needed to understand the real impact of COVID-19. In order to compare the efficiency of different COVID-19 vaccines used in the National Vaccination Program in Tunisia, we have developed a quantitative in-house ELISA. Methods: The ELISA is based on the ectodomain of the SARS-CoV-2 Spike Baculovirus recombinant protein. We have used a panel of 145 COVID-19 RT-PCR positive serum samples and 116 pre-pandemic serum samples as a negative panel. The validation was carried out by comparison to four commercial techniques (Vidas® SARS-CoV-2 IgG anti-RBD Biomérieux®, Elecsys® Anti-Nucleocapsid of SARS-CoV-2 Roche®, cPass® GenScript® and the quantitative Elecsys® Anti-RBD of SARS-CoV-2, Roche®). For the evaluation of the National Vaccination campaign, we have included 115 recipients of one of the different used vaccines.Results: The qualitative performances of the developed ELISA gave 96% sensitivity, 97.5% specificity and 0.968 accuracy. For the evaluation of the different brand of vaccines in recipients not previously infected with SARS-CoV-2, it seems that mRNA vaccine of Pfizer/BioNTech has shown a higher efficacy compared to inactivated virus vaccines. COVID-19 convalescent individuals have generated poor antibody responses. Nevertheless, when they are vaccinated with any brand of the COVID-19 vaccines, many of them mounted an exponential increase of the induced immune responses, qualified as a “hybrid vigor immunity”.Conclusion: Our developed in-house ELISA seems to be very efficient in evaluating the effectiveness of anti-COVID-19 vaccination. Platforms based on mRNA vaccine are better performing than that based on inactivated virus.

show abstract

Covid-19: Antibody levels fall after second Pfizer dose, but protection against severe disease remains, studies indicate

Abstract: Six months after the second dose of the Pfizer-BioNTech covid-19 vaccine, antibody concentrations in healthcare workers had decreased substantially, especially among older men and immunosuppressed people, a study has found. 1

Cited by 5 publications

References 2 publications

A stochastic particle extended SEIRS model with repeated vaccination: Application to real data of COVID‐19 in Italy

A stochastic particle extended SEIRS model with repeated vaccination: Application to real data of COVID‐19 in Italy

Development of an in-house quantitative ELISA for the evaluation of different Covid-19 vaccines in humans

Development of an in-house Quantitative ELISA for the Evaluation of Different Covid-19 Vaccines in Human

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