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. 2023 Aug:133:36-42.
doi: 10.1016/j.ijid.2023.04.401. Epub 2023 Apr 20.

Vaccine effectiveness of primary and booster COVID-19 vaccinations against SARS-CoV-2 infection in the Netherlands from July 12, 2021 to June 6, 2022: A prospective cohort study

Anne J Huiberts  1 , Brechje de Gier  1 , Christina E Hoeve  1 , Hester E de Melker  1 , Susan J M Hahné  1 , Gerco den Hartog  1 , Diederick E Grobbee  2 , Janneke H H M van de Wijgert  3 , Susan van den Hof  1 , Mirjam J Knol  4
Affiliations

Vaccine effectiveness of primary and booster COVID-19 vaccinations against SARS-CoV-2 infection in the Netherlands from July 12, 2021 to June 6, 2022: A prospective cohort study

Anne J Huiberts et al. Int J Infect Dis. 2023 Aug.

Abstract

Objectives: We estimated vaccine effectiveness (VE) of primary and booster vaccinations against SARS-CoV-2 infection overall and in four risk groups defined by age and medical risk condition during the Delta and Omicron BA.1/BA.2 periods.

Methods: VAccine Study COvid-19 is an ongoing prospective cohort study among Dutch adults. The primary end point was a self-reported positive SARS-CoV-2 test from July 12, 2021 to June 06, 2022. The analyses included only participants without a previous SARS-CoV-2 infection based on a positive test or serology. We used Cox proportional hazard models with vaccination status as the time-varying exposure and adjustment for age, sex, educational level, and medical risk condition.

Results: A total of 37,170 participants (mean age 57 years) were included. In the Delta period, VE <6 weeks after the primary vaccination was 80% (95% confidence interval 69-87) and decreased to 71% (65-77) after 6 months. VE increased to 96% (86-99) shortly after the first booster vaccination. In the Omicron period, these estimates were 46% (22-63), 25% (8-39), and 57% (52-62), respectively. For the Omicron period, an interaction term between vaccination status and risk group significantly improved the model (P <0.001), with generally lower VEs for those with a medical risk condition.

Conclusion: Our results show the benefit of booster vaccinations against infection, also in risk groups; although, the additional protection wanes quite rapidly.

Keywords: COVID-19; SARS-CoV-2; Vaccine effectiveness.

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Conflict of interest statement

Declarations of competing interest The authors have no competing interests to declare.

Figures

Figure 1
Figure 1
The 7-days moving average of number of infections reported per 100,000 VAccine Study COvid-19 (VASCO) participants by vaccination status from July 12, 2021 to June 06, 2022
Figure 2
Figure 2
Vaccine effectivenessa for primary vaccination series and first booster vaccination in Delta and Omicron BA.1/BA.2 period from July 12, 2021 to June 06, 2022 aAdjusted for age group, sex, educational level, medical condition.
Figure 3
Figure 3
Vaccine effectivenessa for primary vaccination series and first booster vaccination in Delta and Omicron BA.1/BA.2 period in participants with high intention to test if experiencing symptoms from July 12, 2021 to June 06, 2022. aAdjusted for age group, sex, educational level, medical condition.
Figure 4
Figure 4
Vaccine effectivenessa for primary vaccination series, booster and second booster vaccination per risk group in the Omicron BA.1/BA.2 period from January 10, 2022 to June 06, 2022. aVaccine effectiveness was not reported when number of person-weeks <500; Adjusted for age group, sex, educational level.
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References

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