201,536 positive COVID-19 tests were reported to RIVM National Institute for Public Health and the Environment last week*. That is an increase of 77% compared to the previous week. Such high numbers of reported infections within just one week have never been seen before in the Netherlands.

The virus spreads through contact between people. The Omicron variant is known to spread faster than the previous variants of the coronavirus SARS-CoV-2. As a result, the number of reported positive COVID-19 tests last week rose to 201,356. Reported figures are rising in all regions of the Netherlands.

The highest number of reported positive tests per 100,000 inhabitants last week were in the age group of 18-29 years. The highest absolute number of infections and the highest number of infections per 100,000 inhabitants was in the age group of 18-24 years. The number of reported positive tests per 100,000 inhabitants among people aged 18-24 years tripled last week compared to the previous week. Among people aged 13-17 years and people aged 25-29 years, the number of reported positive tests per 100,000 inhabitants doubled within a week. Hardly any increase has been observed in reported figures for people over 60 (Figure 1).

Figure 1: Number of reported positive tests per 100,000 inhabitants, by age group (29 November 2021 to 9 January 2022).

Nearly 590,000 people were tested by the Municipal Public Health Services (GGDs), 66% more than in the week before that. The percentage of positive tests continued to increase, rising to 34.2%. After a positive self-test, more and more people are going to the GGD for a confirmation test. Among people who went to the GGD for a confirmation test after a positive self-test, 88% received a positive test result. About 23% of COVID-19 tests by the GGD, and 53% of all positive COVID-19 tests by the GGD, have taken place after a positive self-test (based on available information). 

Reinfections

The number of reinfections – defined as people who are infected with SARS-CoV-2 again two months or more after their previous infection – is rising sharply. From early summer to mid-December 2021, about 3% of reported positive tests involved a reinfection. With the increase in cases involving the Omicron variant, the percentage of reinfections is rising sharply. In week 51 of 2021, 5% of cases involved a reinfection, rising to 8% a week later. In the first week of this year (3 to 9 January 2022), this percentage continued to increase, rising to 13%. 

Figuur 2 Aantal personen met vastegestelde herinfectie

Figure 2: Number of people with a confirmed reinfection among all reported people with a positive result on a COVID-19 test (SARS-CoV-2) from 4 January 2021 to 9 January 2022.

Hospitals

The number of patients with COVID-19 admitted to hospital and ICU is decreasing. This is in line with the fact that relatively few older people have tested positive in recent weeks; these people have a higher risk of hospitalisation. During the past week (3-9 January), 873 people were admitted to hospital nursing wards (1,046 in the previous week) and 143 people were admitted to ICU (171 in the previous week). People who are currently admitted to hospital with COVID-19 could have the Delta variant or the Omicron variant. How the increase in reported positive tests due to the Omicron variant will influence the number of new hospital admissions will become apparent in the next few weeks.

Reproduction numbers 

The most recent reproduction number for SARS-CoV-2 (27 December 2021) was 1.26 (1.24 – 1.28). That means that 100 people who had COVID-19 on 27 December 2021 will collectively infect another 126 new people. The Omicron variant is spreading much faster than the previous variants of the coronavirus SARS-CoV-2. The faster spread is clearly visible if we separate the R number for the Delta variant from the R number for the Omicron variant. The Delta variant on its own has a reproduction number of 0.78 (0.68 – 0.88). That means that 100 people who had COVID-19 on 27 December 2021 only infected 78 new people. The reproduction number for the Omicron variant is 1.63 (1.59 – 1.68). 100 people who have the Omicron variant will infect another 163 new people. Since late December 2021, the Omicron variant has caused the most SARS-CoV-2 infections in the Netherlands.
 

Figuur 3 Het reproductiegetal van de deltavariant

Figure 3: The reproduction number of the Delta variant is dropping, while the reproduction number of the Omicron variant is rising. The figure shows how many people would be infected if these reproduction numbers stayed the same for several days in a row. 

Measures

Prevent the spread of the virus and help to prevent more hospital admissions by following the current measures, even if you are vaccinated. Get vaccinated if you have not yet done so, and get the booster to refresh your protection. 

 * Positive tests reported to RIVM National Institute for Public Health and the Environment between 4 January at 10:01 and 11 January at 10:00. 
The number of GGD tests, hospital admissions and ICU admissions are shown by calendar week.

All the weekly COVID-19 figures are presented in a table and in graphs on the RIVM-website.