Booster vaccination offers significantly improved protection against Omicron

Since December 2021, an increasing percentage of hospital admissions due to COVID-19 have been caused by infection with the Omicron variant. Between 26 January and 8 February 2022, an estimated 94% of hospital admissions were caused by Omicron. Vaccination provides less effective protection against the Omicron variant compared to the previous Delta variant. People who get a booster vaccination have more effective protection against hospital admission than people who have only been vaccinated with the basic series. The booster vaccination offers 92% protection against hospital admission, while the basic series of vaccinations offers 55% protection. 

Vaccination effective in preventing ICU admission

The booster vaccination is also highly effective against ICU admission, reaching 98% in the period between 26 January and 8 February 2022. Vaccination with the basic series also offers protection against ICU admission, but to a lesser extent: 74%. The risk of ICU admission after a booster vaccination was more than 50 times lower than the risk of ICU admission without vaccination. After vaccination with the basic series without a booster, the risk of ICU admission was 4 times lower than without vaccination. 

Number of prevented hospital admissions

From 26 January to 8 February 2022, 1,746 people were admitted to hospital due to COVID-19. 780 of these people had not been vaccinated, while 626 had completed the basic series and 340 had received a booster after the basic series. It is estimate that the extra protection offered by the booster vaccination prevented 1,620 hospital admissions during this period. In other words, there would have been nearly twice as many hospital admissions without the booster vaccination.

Figure 1A: Actual number* of hospital admissions divided by vaccination status in the period from 26 January to 8 February 2022. 1,746 people with SARS-CoV-2 were admitted to hospital in that period. 

 

Figure 1B: Actual number* of hospital admissions in the period from 26 January to 8 February 2022 and estimated hospital admissions prevented by the booster campaign in this period. 

*each square represents 10 admissions

Sources

The analysis is based on NICE data on hospital admissions of patients with COVID-19 admitted until 8 February 2022. The data was enriched on 9 February 2021 with vaccination data from the COVID-19 Information and Monitoring System (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. Since 25 January, new entries in the NICE records include a question regarding the reason for the patient’s admission. Patients who indicated that they were admitted for a reason other than COVID-19 were not included in this analysis.

Please note: raw data and data at hospital level cannot be published due to its privacy-sensitive nature.