Affiliation between booster breakthrough infections with the SARS-CoV-2 Omicron variant and time-since-vaccination

A current examine posted to the medRxiv* preprint server assessed the waning efficacy of the BioNTech/Pfizer BNT162b2 messenger RNA (mRNA) vaccine towards the extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant of concern (VOC).

Study: Waning Effectiveness of the Third Dose of the BNT162b2 mRNA COVID-19 Vaccine. Image Credit: bht2000/Shutterstock
Research: Waning Effectiveness of the Third Dose of the BNT162b2 mRNA COVID-19 Vaccine. Picture Credit score: bht2000/Shutterstock

Varied research have demonstrated the waning effectiveness of the short-term immunity induced by two doses of the BNT162b2 coronavirus illness 2019 (COVID-19) vaccine. Reviews of breakthrough SARS-CoV-2 infections have additional necessitated the administration of a 3rd (booster) dose of the mRNA vaccine. Nevertheless, the extent and period of vaccine-induced safety want intensive analysis.

Concerning the examine

The current examine carried out a retrospective evaluation to look at the correlation between breakthrough SARS-CoV-2 Omicron infections and the interval handed since administering a booster dose.

The examine concerned people 16 years and older who obtained a minimal of two BNT162b2 vaccine doses by 1 August 2021, excluding people with a COVID-19-positive polymerase chain response (PCR) take a look at. The group obtained demographic information together with gender, age, residential socioeconomic geographical statistical space (GSA), and comorbidities and COVID-19-related information, together with dates of administration of vaccines, associated hospitalizations, SARS-CoV-2 PCR outcomes, and associated mortality studies. The examine contributors had been labeled into totally different teams, representing various intervals post-vaccination.

Two SARS-CoV-2-related outcomes had been evaluated: 1) the variety of breakthrough infections, outlined as COVID-19-positive reverse transcription-PCR (RT-PCR) assay carried out seven days or extra after the newest vaccine dose, and a couple of) the manifestation of extreme illness, outlined as both COVID-19-related hospitalization or associated demise. 

All of the contributors had been matched 1:1 primarily based on their gender, age, GSA, week of PCR-testing, and month of receipt of second vaccine dose. The examine concerned a test-negative case-control design with COVID-19 circumstances outlined as sufferers with a PCR-positive consequence or with extreme SARS-CoV-2 manifestation. On the identical time, controls had been PCR-negative people with neither a positive-PCR take a look at nor associated hospitalization of their matched affected person nor whose PCR take a look at was not carried out because the fourth vaccine dose administration, if any.

The group additionally carried out three further analyses, together with a sensitivity evaluation that assessed the incidence of breakthrough infections attributable to booster vaccines. This second sensitivity evaluation eradicated potential selectivity bias of excluding PCR exams of early vaccinees and repeated efficiency of the principle evaluation with a unique reference group to judge the marginal effectiveness of the booster vaccine as in comparison with the second dose.    


The examine outcomes confirmed that 546,924 SARS-CoV-2 PCR exams had been collected from 389,265 contributors from 1 January to 21 January 2022. Within the follow-up interval, 101,737 booster breakthrough infections and 482 breakthrough infections inflicting hospitalizations and deaths had been noticed.

Among the many contributors who obtained the third dose in August and December 2021, the group discovered 30,870 and 1082 breakthrough infections, 208 and 4 associated hospitalizations, and   9 and nil deaths, respectively. Sufferers administered with solely two vaccine doses had 16,938 infections and 122 associated hospitalizations.

A complete of 110,918 circumstances and controls had been matched within the 1:1 ratio to research breakthrough infections, whereas 562 circumstances and controls had been matched for extreme COVID-19 evaluation. Amongst contributors vaccinated in December 2021, vaccine effectiveness (VE) was 53.4%, with a subsequent decline of 35.7% for contributors vaccinated in November 2021 and 16.5% for these vaccinated in October 2021.

The sensitivity analyses resulted in an estimated VE just like that in the principle evaluation. The third further evaluation concerned 128,854 people for the evaluation of breakthrough infections and 722 individuals for the evaluation of extreme COVID-19 occurrences. Amongst these, the marginal effectiveness of the booster dose administered in December 2021 was 59.4%, with the effectiveness lowering from 72.2% to 54.5% three and 5 months after booster vaccination, respectively.


The test-negative case-control examine discovered a major lower in VE in every subsequent month post-booster dose vaccination, whereas the marginal safety induced by the third dose in comparison with the second dose was much less important over months after receipt of the booster dose.

Furthermore, a time-dependent waning of VE with an preliminary improve in efficacy was noticed extra notably after the booster dose than the second dose. The researchers consider that the current examine is essential to immediate discussions concerning COVID-19 vaccination insurance policies to develop booster doses and their administration.

*Vital discover

medRxiv publishes preliminary scientific studies that aren’t peer-reviewed and, due to this fact, shouldn’t be thought to be conclusive, information medical apply/health-related conduct, or handled as established data.

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