Vaccine effectiveness against infection and onwards transmission of COVID-19: Analysis of Belgian contact tracing data, January-June 2021

Braeye, Toon; Cornelissen, Laura; Catteau, Lucy; Haarhuis, Freek; Proesmans, Kristiaan; Ridder, Karin De; Djiena, Achille; Mahieu, Romain; Leeuw, Frances De; Dreuw, Alex; Hammami, Naïma; Quoilin, Sophie; Oyen, Herman Van; Wyndham-Thomas, Chloé; Cauteren, Dieter Van

doi:10.1016/j.vaccine.2021.08.060

Cited by 44 publications

(55 citation statements)

References 14 publications

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“…Around the world, massive vaccination campaigns started in early 2021 and data about the immunological response emerged in the literature to document the evolution of humoral response in subjects vaccinated against SARS-CoV-2 [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. In most seronegative subjects, antibody response was positive two weeks after the first dose and the peak response was observed around 28 days [ 13 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Waning of IgG, Total and Neutralizing Antibodies 6 Months Post-Vaccination with BNT162b2 in Healthcare Workers

et al. 2021

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Data about the long-term duration of antibodies after SARS-CoV-2 vaccination are still scarce and are important to design vaccination strategies. In this study, 231 healthcare professionals received the two-dose regimen of BNT162b2. Of these, 158 were seronegative and 73 were seropositive at baseline. Samples were collected at several time points. The neutralizing antibodies (NAbs) and antibodies against the nucleocapsid and the spike protein of SARS-CoV-2 were measured. At day 180, a significant antibody decline was observed in seronegative (−55.4% with total antibody assay; −89.6% with IgG assay) and seropositive individuals (−74.8% with total antibody assay; −79.4% with IgG assay). The estimated half-life of IgG from the peak humoral response was 21 days (95% CI: 13–65) in seronegative and 53 days (95% CI: 40–79) in seropositive individuals. The estimated half-life of total antibodies was longer and ranged from 68 days (95% CI: 54–90) to 114 days (95% CI: 87–167) in seropositive and seronegative individuals, respectively. The decline of NAbs was more pronounced (−98.6%) and around 45% of the subjects tested were negative at day 180. Whether this decrease correlates with an equivalent drop in the clinical effectiveness against the virus would require appropriate clinical studies.

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Section: Introductionmentioning

confidence: 99%

Waning of IgG, Total and Neutralizing Antibodies 6 Months Post-Vaccination with BNT162b2 in Healthcare Workers

et al. 2021

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“…[3][4][5][6][7] Around the world, massive vaccination campaigns started in early 2021 and data about the immunological response emerged in the literature to document the evolution of humoral response in subjects vaccinated against SARS-CoV-2. [8][9][10][11][12][13][14][15] In the majority of seronegative subjects, antibody response was positive two weeks after the rst dose and the peak response was observed around 28 days. 13,16 The antibody titers were also higher in previously infected individuals compared to seronegative subjects and recent studies found a decline in antibody titers at 3 months.…”

Section: Introductionmentioning

confidence: 99%

Waning of IgG, total and neutralizing antibodies 6 months post-vaccination with BNT162b2 in healthcare workers

Bayart

Douxfils

Gillot

et al. 2021

Preprint

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Data about the duration of humoral response following COVID-19 vaccines are mandatory to establish appropriate population vaccination strategy. This study reports on the antibody decline observed in a population of COVID-19 naïve and COVID-19 positive individuals having received the two dose regimen of the BNT162b2 vaccine. Six months after vaccination, a significant antibody decline was observed in both COVID-19 naïve and positive individuals. The estimated half-life of total and IgG antibodies differs and ranges from several months for total antibodies to only several weeks for IgG antibodies, explaining the significant proportions of participants with non-detectable levels of neutralizing antibodies at 6 months. Whether this decrease correlates with an equivalent drop in the clinical effectiveness against the virus will require appropriate clinical studies. Nevertheless, these data are already important to support the decision-making on the potential use of a booster dose.

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“…A study from Belgium, based on a similar contact tracing system, also described significant protection against infection after a close contact; however, the study only examined fully vaccinated IPs. Moreover, additional protection against transmission was demonstrated when the CP was also fully vaccinated [20]. A retrospective analysis from England confirmed lower transmission to close contacts among vaccinated persons for the Alpha variant and the same effect but somewhat less pronounced for the Delta variant [21].…”

Section: Discussionmentioning

confidence: 89%

COVID-19 Breakthrough Infections and Transmission Risk: Real-World Data Analyses from Germany’s Largest Public Health Department (Cologne)

Hsu

Grüne²,

Buess³

et al. 2021

Vaccines

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Background and Methods: Vaccination is currently considered the most successful strategy for combating the SARS-CoV-2 virus. According to short-term clinical trials, protection against infection is estimated to reach up to 95% after complete vaccination (≥14 days after receipt of all recommended COVID-19 vaccine doses). Nevertheless, infections despite vaccination, so-called breakthrough infections, are documented. Even though they are more likely to have a milder or even asymptomatic course, the assessment of further transmission is highly relevant for successful containment. Therefore, we calculated the real-world transmission risk from fully vaccinated patients (vaccination group, VG) to their close contacts (CP) compared with the risk from unvaccinated reference persons matched according to age, sex, and virus type (control group = CG) utilizing data from Cologne’s health department. Results: A total of 357 breakthrough infections occurred among Cologne residents between 27 December 2020 (the date of the first vaccination in Cologne) and 6 August 2021. Of the 979 CPs in VG, 99 (10.1%) became infected. In CG, 303 of 802 CPs (37.8%) became infected. Factors promoting transmission included non-vaccinated status (β = 0.237; p < 0.001), male sex (β = 0.079; p = 0.049), the presence of symptoms (β = −0.125; p = 0.005), and lower cycle threshold value (β = −0.125; p = 0.032). This model explained 14.0% of the variance (corr. R2). Conclusion: The number of transmissions from unvaccinated controls was three times higher than from fully vaccinated patients. These real-world data underscore the importance of vaccination in enabling the relaxation of stringent and restrictive general pandemic control measures.

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Vaccine effectiveness against infection and onwards transmission of COVID-19: Analysis of Belgian contact tracing data, January-June 2021

Cited by 44 publications

References 14 publications

Waning of IgG, Total and Neutralizing Antibodies 6 Months Post-Vaccination with BNT162b2 in Healthcare Workers

Waning of IgG, Total and Neutralizing Antibodies 6 Months Post-Vaccination with BNT162b2 in Healthcare Workers

Waning of IgG, total and neutralizing antibodies 6 months post-vaccination with BNT162b2 in healthcare workers

COVID-19 Breakthrough Infections and Transmission Risk: Real-World Data Analyses from Germany’s Largest Public Health Department (Cologne)

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