Effectiveness of booster vaccination in preventing hospital and ICU admission
The booster vaccination campaign in the Netherlands started on 18 November 2021. For the first time, RIVM can now provide an update on the effectiveness of booster vaccination in preventing hospital and ICU admission. From 19 November 2021 to 13 January 2022, vaccine effectiveness for people who had received a booster vaccination was 97% against hospital admission and 98% against ICU admission.
Most hospital admissions due to COVID-19 since the start of the booster campaign have still been caused by the Delta variant of the coronavirus SARS-CoV-2. Vaccine effectiveness between 19 November and 13 January is therefore mainly related to the Delta variant. It is not yet possible to estimate vaccine effectiveness against hospital admission due to the Omicron variant. Data from the UK indicates that the basic series of vaccinations as well as the booster offers less protection against the Omicron variant than against Delta, but that a booster vaccination still provides much more protection against Omicron than the basic series on its own.
Extra protection from booster vaccination
A booster vaccination provides 12 percentage points** more protection against hospital admission than only completing the basic series of COVID-19 vaccinations (97% compared to 85%). This means that the risk of hospital admission after a booster vaccination is 5 times lower than if you have only completed the basic series. That increase is 20 percentage points for people over 70 (96% compared to 76%), and 9 percentage points for people aged 12-69 (98% compared to 89%). The basic series gradually decreases in vaccine effectiveness over time, but effectiveness increases again after a booster.
The vaccine effectiveness of booster vaccination will be monitored in the next few months to track effectiveness in relation to the Omicron variant and how it develops over time, based on how long it has been since a person received the booster vaccination.
The analysis is based on NICE data on hospital admissions of patients with COVID-19 admitted until 13 January 2022. The data was enriched on 14 January 2022 with vaccination data from the central COVID-19 vaccination register (CIMS). The method used to calculate vaccine effectiveness is explained in the report: Study: Effectiveness of COVID-19 vaccination against hospital and ICU admission in the Netherlands
Please note: raw data cannot be published due to its privacy-sensitive nature.
* These probabilities can be derived directly from vaccine effectiveness: reduced probability=100/(100-vaccine effectiveness).
** One percentage point represents the absolute difference between two percentages.