Questioning the justification for a fourth SARS-CoV-2 vaccine

Calderon‐Margalit, Ronit; Strahilevitz, Jacob; Paltiel, Ora

doi:10.1016/j.cmi.2022.03.023

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…In an effort to address the challenges presented by this variant and to reduce the load on the healthcare system, on 2 January 2022, Israeli authorities were the first in the world to approve the administration of a fourth vaccine dose (second booster) for individuals aged 60 and over, high-risk populations, and HCWs who had received a first booster at least 4 months earlier. The major argument for this decision was that the expected benefit of reduced transmission and disease from a booster dose would outweigh the potential risks [ 6 ]. This decision was highly controversial due to the lack of evidence available at the time [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Attitudes of Healthcare Workers in Israel towards the Fourth Dose of COVID-19 Vaccine

Ramot

Tal

2023

Vaccines

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Attitudes of healthcare workers (HCWs) toward vaccines are extremely important for increasing vaccination coverage. We conducted a cross-sectional study at the beginning of the fourth COVID-19 vaccination dose campaign among 124 HCWs to evaluate attitudes towards the fourth dose and willingness to get vaccinated. At that time, Israel was the first country to approve the fourth vaccine dose. Most women were unwilling to get the fourth vaccine dose compared to men; 53.9% of physicians were unwilling to get vaccinated compared to 83.3% of nurses and 69% of other HCWs professions. The most frequent concerns regarding the vaccine were its efficacy, benefit, and necessity. The perceived risk and perceived severity of the health risk involved with getting vaccinated with the fourth dose were higher among HCWs who stated that they would not get vaccinated compared to those who were vaccinated or intended to get vaccinated. In contrast, HCWs who were vaccinated with the fourth dose, or those who were planning to get vaccinated, gave higher scores to the perceived benefit of the booster, its advantages, its perceived safety, its ability to protect from severe illness, and the perceived extent of scientific information about the risk associated with the booster. A logistic regression model revealed that perception of the fourth dose’s benefits and risk significantly predict the willingness of HCWs to get vaccinated. Willingness to vaccinate their own children, acceptance of a hypothetical annual booster vaccine, and having less severe adverse effects after prior vaccination were also associated with willingness to get the fourth dose. These findings could help policy makers in developing strategies to expand the acceptance and coverage of the COVID-19 booster doses.

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Section: Introductionmentioning

confidence: 99%

Attitudes of Healthcare Workers in Israel towards the Fourth Dose of COVID-19 Vaccine

Ramot

Tal

2023

Vaccines

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“…Even though the extent of vaccination-induced protection is still uncertain, health authorities in Western countries have approved the application of booster doses to ensure that high immunity levels against the VOCs are maintained in the population (Levine-Tiefenbrun et al 2021 ; Joshi et al 2021 ). Despite the serious ethical concerns raised by this decision when one-third of the world’s population still lacks access to any vaccine, third and even fourth vaccine doses have been administered in several countries (Barry et al 2021 ; Calderon-Margalit et al 2021 ). There is still limited information about which vaccines can be combined in a booster schedule to improve immunity (Lopez Bernal et al 2021b ).…”

Section: Discussionmentioning

confidence: 99%

Caveats of chimpanzee ChAdOx1 adenovirus-vectored vaccines to boost anti-SARS-CoV-2 protective immunity in mice

Cervantes-Torres,

Cabello-Gutiérrez,

Ayón-Núñez

et al. 2024

Appl Microbiol Biotechnol

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Several COVID-19 vaccines use adenovirus vectors to deliver the SARS-CoV-2 spike (S) protein. Immunization with these vaccines promotes immunity against the S protein, but against also the adenovirus itself. This could interfere with the entry of the vaccine into the cell, reducing its efficacy. Herein, we evaluate the efficiency of an adenovirus-vectored vaccine (chimpanzee ChAdOx1 adenovirus, AZD1222) in boosting the specific immunity compared to that induced by a recombinant receptor-binding domain (RBD)-based vaccine without viral vector. Mice immunized with the AZD1222 human vaccine were given a booster 6 months later, with either the homologous vaccine or a recombinant vaccine based on RBD of the delta variant, which was prevalent at the start of this study. A significant increase in anti-RBD antibody levels was observed in rRBD-boosted mice (31–61%) compared to those receiving two doses of AZD1222 (0%). Significantly higher rates of PepMix™- or RBD-elicited proliferation were also observed in IFNγ-producing CD4 and CD8 cells from mice boosted with one or two doses of RBD, respectively. The lower efficiency of the ChAdOx1-S vaccine in boosting specific immunity could be the result of a pre-existing anti-vector immunity, induced by increased levels of anti-adenovirus antibodies found both in mice and humans. Taken together, these results point to the importance of avoiding the recurrent use of the same adenovirus vector in individuals with immunity and memory against them. It also illustrates the disadvantages of ChAdOx1 adenovirus-vectored vaccine with respect to recombinant protein vaccines, which can be used without restriction in vaccine-booster programs. Key points • ChAdOx1 adenovirus vaccine (AZD1222) may not be effective in boosting anti-SARS-CoV-2 immunity • A recombinant RBD protein vaccine is effective in boosting anti-SARS-CoV-2 immunity in mice • Antibodies elicited by the rRBD-delta vaccine persisted for up to 3 months in mice

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“…The administration of a fourth dose is currently under discussion 56 and some interim recommendations have been formulated. 57 , 58 Considering the waning of VE over time and the considerable immune escape of new emerging variants, the fourth dose seems unavoidable to restore a sufficient level of neutralizing antibodies.…”

Section: Discussionmentioning

confidence: 99%

Vaccine‐induced binding and neutralizing antibodies against Omicron 6 months after a homologous BNT162b2 booster

Favresse

Gillot

Bayart

et al. 2022

Journal of Medical Virology

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Evidence about the long‐term persistence of the booster‐mediated immunity against Omicron is mandatory for pandemic management and deployment of vaccination strategies. A total of 155 healthcare professionals (104 COVID‐19 naive and 51 with a history of SARS‐CoV‐2 infection) received a homologous BNT162b2 booster. Binding antibodies against the spike protein and neutralizing antibodies against Omicron were measured at several time points before and up to 6 months after the booster. Geometric mean titers of measured antibodies were correlated to vaccine efficacy (VE) against symptomatic disease. Compared to the highest response, a significant 10.2‐ and 11.5‐fold decrease in neutralizing titers was observed after 6 months in participants with and without history of SARS‐CoV‐2 infection. A corresponding 2.5‐ and 2.9‐fold decrease in binding antibodies was observed. The estimated T 1/2 of neutralizing antibodies in participants with and without history of SARS‐CoV‐2 infection was 42 (95% confidence interval [CI]: 25–137) and 36 days (95% CI: 25–65). Estimated T 1/2 were longer for binding antibodies: 168 (95% CI: 116–303) and 139 days (95% CI: 113–180), respectively. Both binding and neutralizing antibodies were strongly correlated to VE ( r = 0.83 and 0.89). However, binding and neutralizing antibodies were modestly correlated, and a high proportion of subjects (36.7%) with high binding antibody titers (i.e., >8434 BAU/ml) did not have neutralizing activity. A considerable decay of the humoral response was observed 6 months after the booster, and was strongly correlated with VE. Our study also shows that commercial assays available in clinical laboratories might require adaptation to better predict neutralization in the Omicron era.

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Questioning the justification for a fourth SARS-CoV-2 vaccine

Cited by 4 publications

References 8 publications

Attitudes of Healthcare Workers in Israel towards the Fourth Dose of COVID-19 Vaccine

Attitudes of Healthcare Workers in Israel towards the Fourth Dose of COVID-19 Vaccine

Caveats of chimpanzee ChAdOx1 adenovirus-vectored vaccines to boost anti-SARS-CoV-2 protective immunity in mice

Vaccine‐induced binding and neutralizing antibodies against Omicron 6 months after a homologous BNT162b2 booster

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