Omicron subvariant BA.2 dominant in the Netherlands

As of this week, the most common variant of the coronavirus SARS-CoV-2 in the Netherlands is BA.2, a sub-variant of the Omicron variant. This means that the majority of people who test positive for COVID-19 have this variant of the coronavirus. The BA.2 variant differs from the BA.1 variant in several ways, including the spike protein. BA.2 appears to be more contagious than BA.1. Data from the UK and Denmark suggests that BA.2 spreads much more easily within households than BA.1. There is currently no evidence that BA.2 causes more serious illness than BA.1. Vaccine-induced protection against infection with the BA.2 subvariant, like protection against infection with the BA.1 subvariant, is lower in people who only received the basic series of COVID-19 vaccinations some time ago. A booster vaccination increases protection against infection with both Omicron subvariants BA.1 and BA.2. 

Since its emergence, the BA.2 subvariant has been increasing in pathogen surveillance in the Netherlands in recent weeks. Pathogen surveillance is a national check of about 2,000 test samples randomly selected every week. Based on data from pathogen surveillance and from laboratories that use PCR tests which offer an indication of the presence of the BA.2 subvariant, BA.2 is expected to become the dominant subvariant of the Omicron variant this week, replacing the BA.1 subvariant that is currently causing the highest number of infections.

Positive COVID-19 tests

In the past week, the number of people who tested positive for COVID-19 decreased by 22% compared to the week before that. A total of 482,695 positive tests were reported to RIVM in the past week. 833,178 people came to the test lanes of the Municipal Public Health Services (GGDs) to get tested for SARS-CoV-2. That is 15% fewer tests than the week before. The number of positive tests decreased in all age groups, with the exception of people over 70 years. In the age groups of 70-79 years and 80+ years, the number of reported positive tests per 100,000 inhabitants is lower than in younger age groups, but still increased by 27% and 35% respectively. The biggest decrease was seen in the age group of 13-17 years, but that age group still had the highest number of reported positive tests per 100,000 inhabitants (Figure 1).

Figure 1: Number of reported positive tests per 100,000 inhabitants, by age group (3 January 2022 to 13 February 2022).

Hospital admissions and reason for admission

In the week of 7 February to 13 February 2022, 1,149 new patients with a SARS-CoV-2 infection were admitted to hospital (last week: 1,393, -18%), and 88 of those patients were admitted to ICU (last week: 122, -28%).

Since 25 January 2022, the NICE records have been expanded to record the reason for hospital admission** of new patients with a confirmed SARS-CoV-2 infection who are admitted to nursing wards and to the ICU. In the past three weeks, there has been hardly any change in the distribution of patients with COVID-19 based on admission reason. In ICU and in nursing wards, COVID-19 is the main reason or one of the reasons for admission in 8 out of 10 patients with SARS-CoV-2. The following provides a more detailed update on the data on nursing wards and ICU since 25 January 2022.

Between 25 January and 14 February, 3,575 patients with a SARS-CoV-2 infection were admitted to hospital in the Netherlands. For 39% of these patients, the reason for hospital admission was not (yet) known; for 2,191 of the patients with a SARS-CoV-2 infection, the reason for hospital admission was known. For 52%, COVID-19 was the main reason for hospital admission. In 30% of admitted patients with a known admission reason, the SARS-CoV-2 infection had exacerbated a pre-existing health condition. Without a SARS-CoV-2 infection, these vulnerable patients would not have been admitted to hospital. COVID-19 was the main reason or one of the relevant reasons for hospital admission in 81% of the patients with known admission reasons between 25 January and 14 February 2022 (see Figure 2). 

Between 25 January and 14 February, 282 patients with a SARS-CoV-2 infection were admitted to ICU in the Netherlands. For 20% of these patients, the reason for admission was not (yet) known; for 226 of the patients with a SARS-CoV-2 infection, the reason for admission was known. For 62%, COVID-19 was the main reason for ICU admission. In 17% of patients admitted to ICU with a known admission reason, the SARS-CoV-2 infection had exacerbated a pre-existing health condition. Without COVID-19, these vulnerable patients would not have been admitted to ICU. COVID-19 was the main reason for ICU admission in 79% of the patients with known admission reasons (see Figure 3). In all age groups, COVID-19 was the most common reason or trigger for ICU admission. 

Figure 2: Admission reason** for 2,191 of the 3,575 patients with SARS-CoV-2 admitted to nursing wards between 25 January and 14 February 2022, as recorded by 15 February 2022 at 00:00. 

Figure 3: Admission reason** for 226 of the 282 patients with SARS-CoV-2 admitted to intensive care units between 25 January and 14 February 2022, as recorded by 15 February 2022 at 00:00.

Reproduction number R

The most recent reproduction number for SARS-CoV-2 (31 January 2022) was 0.98 (0.97 – 0.98). The reproduction number decreased compared to the week before that (1.11 on 24 January 2022). That means that 100 people who had COVID-19 on 31 January 2022 will collectively infect another 98 new people. 

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 between 8 February 2022 at 10:01 and 15 February 2022 at 10:00.
The number of GGD tests, hospital admissions and ICU admissions are shown by calendar week.

** The admission reason for patients with SARS-CoV-2 has been divided into 4 categories. 

1. Due to COVID-19: COVID-19 is the reason for the patient’s admission and the patient is treated for that disease.
2. Combination with COVID-19: COVID-19 is one of the reasons for admission: the patient is admitted because COVID-19 has exacerbated a pre-existing health condition, such as diabetes or heart failure. The patient would not have needed to be admitted without COVID-19.
3. Other reason for admission: The reason for admission is not related to COVID-19: The patient is admitted for a different and does not need treatment for the SARS-CoV-2 infection. 
4. Unknown: It is not (yet) known whether the reason for admission is related to the SARS-CoV-2 infection.