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. 2022 Jul 8;17(7):e0270801.
doi: 10.1371/journal.pone.0270801. eCollection 2022.

Protection provided by vaccination, booster doses and previous infection against covid-19 infection, hospitalisation or death over time in Czechia

Luděk Berec  1   2   3 , Martin Šmíd  3   4 , Lenka Přibylová  5 , Ondřej Májek  6   7 , Tomáš Pavlík  6   7 , Jiří Jarkovský  6   7 , Milan Zajíček  4 , Jakub Weiner  3   8 , Tamara Barusová  9   10 , Jan Trnka  11
Affiliations

Protection provided by vaccination, booster doses and previous infection against covid-19 infection, hospitalisation or death over time in Czechia

Luděk Berec et al. PLoS One. .

Erratum in

Abstract

Studies demonstrating the waning of post-vaccination and post-infection immunity against covid-19 generally analyzed a limited range of vaccines or subsets of populations. Using Czech national health data from the beginning of the covid-19 pandemic till November 20, 2021 we estimated the risks of reinfection, breakthrough infection, hospitalization and death by a Cox regression adjusted for sex, age, vaccine type and vaccination status. Vaccine effectiveness against infection declined from 87% at 0-2 months after the second dose to 53% at 7-8 months for BNT162b2 vaccine, from 90% at 0-2 months to 65% at 7-8 months for mRNA-1273, and from 83% at 0-2 months to 55% at 5-6 months for the ChAdOx1-S. Effectiveness against hospitalization and deaths declined by about 15% and 10%, respectively, during the first 6-8 months. Boosters (third dose) returned the protection to the levels observed shortly after dose 2. In unvaccinated, previously infected individuals the protection against infection declined from 97% after 2 months to 72% at 18 months. Our results confirm the waning of vaccination-induced immunity against infection and a smaller decline in the protection against hospitalization and death. Boosting restores the original vaccine effectiveness. Post-infection immunity also decreases over time.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Dynamics of vaccination in the Czech Republic.
Specific days in which vaccination was open to an age group or professional or other category are specified in S1 Table in S2 File.
Fig 2
Fig 2. Vaccine effectiveness against infection.
Vaccine-acquired immunity against infection with respect to the delay from the full vaccine application, including the effect of a booster vaccine dose.
Fig 3
Fig 3. Estimating potential statistical differences between the vaccines.
A Z-test has been performed to test for those differences. For each pair of covariates (each covariate is characterized by the vaccine and the time interval since completing the corresponding vaccination scheme), a color is assigned to indicate a degree of statistical significance: blue for 1% (|Z| > 2.576), red for 5% (2.576 ≥ |Z| > 1.960), and gray for |Z| ≤ 1.960. Moreover, only pairs with positive values of the test statistic Z are plotted, indicating a positive difference between a respective y-axis covariate and x-axis covariate (values symmetric around the diagonal are negative with the same absolute value). The axis labels are composed of a capital letter (P = BNT162b2 vaccine, M = mRNA-1273 vaccine, A = ChAdOx1-S vaccine, and J = Ad26.COV2-S vaccine) and a number range (months since full vaccination) or ‘boost’ (3rd vaccine dose).
Fig 4
Fig 4. Infection-acquired immunity against reinfection with respect to the delay from the prior infection.
The delay 0–2 months is not considered as a new infection which implies 100% effectiveness by definition.
See this image and copyright information in PMC

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