When a virus replicates, it can change very slightly every time. These changes (or mutations) are usually so small that they have almost no effect on how ill you become and how the virus spreads. Sometimes changes do cause a virus to behave differently, for example allowing it to spread more easily. RIVM monitors changes in the coronavirus SARS-CoV-2 in the Netherlands and the consequences of those changes.

There are already many different variants of the coronavirus SARS-CoV-2. RIVM is conducting laboratory research to see which variants are present in the Netherlands and whether they are increasing in prevalence. This is known as pathogen surveillance. This research is important to know whether new variants that pose additional risks are increasing rapidly in the Netherlands. Some changes (mutations) can cause a variant to spread more quickly or make people more severely ill. Other mutations change the external appearance of the virus, making it harder for the immune system to detect it after a previous infection or vaccination.

Current situation: Omicron BQ.1 (and BQ.1.1) variants are decreasing

Since early 2022, most of the variants of SARS-CoV-2 circulating in the Netherlands are in the Omicron lineage: sub-variants BA.1 through BA.5. But mutations are also emerging within these sub-variants, developing from Omicron. The same pattern is occurring in other countries as well.

Multiple sub-variants of BA.2, BA.4 and BA.5 are currently circulating in the Netherlands. From BA.2, we are seeing sub-variants BA.2.75. From BA.4, we are seeing sub-variant BA.4.6. Sub-variants of BA.5 include BF.7 and BQ.1 (as well as BQ.1.1). Recombinant strains of variants, such as XBB, combine characteristics of other variants.

Omicron BA.1 and BA.2 were initially dominant in the Netherlands, followed by BA.5; since week 48, BQ.1 (including BQ.1.1) had been responsible for the highest number of infections. BQ.1 and BQ.1.1 are now showing a downward trend. We are seeing an increase in BA.2.75 (including sub-variant CH.1.1, which is on the rise in many European countries) and recombinant XBB (including XBB.1.5). The sub-variant that has been rising sharply in the USA, known as XBB.1.5, is also increasing in the Netherlands. The same applies to XBF, a recombinant variant which is rising in Australia, although infections are still limited for now. At this time, there are no indications that these sub-variants would be more likely to cause severe illness compared to previous Omicron sub-variants. 

If a specific SARS-CoV-2 variant or sub-variant is found often enough in pathogen surveillance, RIVM can estimate how the percentage of that variant may develop in the near future. RIVM arrives at these estimates (trend forecasts) based on modelling. The figure below shows the latest trend forecasts. These estimates always have some margin of uncertainty. The latest calculations suggest that XBB (including XBB.1.5) may become dominant in the Netherlands within the near future. However, BA.2.75 (including CH.1.1) and XBF are also increasing, so it is possible that multiple sub-variants may continue circulating simultaneously for some time. New variants or sub-variants may also emerge.
 

The graph shows the Alpha, Delta and Omicron variants (and Omicron sub-variants) of SARS-CoV-2. Sub-variants BA.2.75, BA.4.6, BF7, BQ.1 and XBB are shown separately on the graph.

Many Omicron sub-variants appear to have the same minor changes (mutations) that developed separately. Most of these changes seem to occur in the ‘spike protein’, the lines bristling out from the coronavirus. The minor changes give the virus a slightly better chance to evade immunity resulting from previous infection or vaccination. Sometimes they also make it easier for a variant to attach to host cell receptors. At this time, there are no indications that these variants would be more likely to cause severe illness compared to previous Omicron sub-variants.

Latest SARS-CoV-2 pathogen surveillance results

RIVM is monitoring all variants of SARS-CoV-2 that are observed in the National Pathogen Surveillance. The table below shows the pathogen surveillance results for the Variants of Concern and Variants of Interest identified by the World Health Organization (WHO) and the European Centre for Disease Prevention and Control (ECDC). The ECDC also tracks a category designated as ‘Variants under Monitoring’. These variants are only listed separately in the table if there is a reason to do so, for example in response to significant international indicators or a sudden and rapid increase in a specific variant. The underlying data is public. The relevant sequences are shared in an international database by GISAID.

Week number Total 2023/3 2023/2 2023/1 2022/52 2022/51 2022/50 2022/49 2022/48§ 2020/49 to 2022/47
designation 152044 379 787 1028 1079 1038 1213 1106 1076 144338
Beta (B.1.351)  446 0 0 0 0 0 0 0 0 446
Gamma (P.1)  382 0 0 0 0 0 0 0 0 382
Delta (B.1.617.2) 44450 0 0 0 0 0 0 0 0 44450
Omicron (B.1.1.529) 74419 308 684 944 999 976 1158 1054 1016 67280
Omikron recombinants* 787 71 103 84 80 62 55 52 60 220
BA.1* 15278 0 0 0 0 0 1 0 0 15277
BA.2* 22551 80 167 191 175 158 138 137 110 21395
BA.2.12.1* 765 0 0 0 0 0 0 0 0 765
BA.2.75* 1723 80 164 189 172 153 133 133 103 596
BA.3* 3 0 0 0 0 0 0 0 0 3
BA.4 2464 3 2 11 15 13 16 20 22 2362
BA.4.6*  866 3 1 9 13 10 15 15 18 782
BA.5 34121 225 515 742 809 805 1003 897 884 28241
BF.7* 3670 10 21 40 56 55 97 83 111 3197
BQ.1* 7020 184 428 594 637 623 733 619 553 2649
BQ.1.1* 4804 139 340 449 452 445 522 434 366 1657
XBB 594 54 87 71 60 50 45 46 50 131
XBB.1.5 202 38 49 43 30 18 14 5 4 1

Download the table of virus variants

Pathogen surveillance data is updated weekly. The figures for the last few weeks may sometimes still change slightly. This is because new reports may be added from data provided by the (current and new) laboratories participating in pathogen surveillance. The figures displayed per week may also differ from previous weekly updates, for example if the sample collection date has been updated. Information about last week is not yet complete.

As of 26 November 2021, B.1.1.529 was designated as a VOC by ECDC and WHO and is therefore included in the table. AY.4.2, B.1.616, B.1.620, B.1.427/429 (Epsilon), P.3 (Theta), B.1.525 (Eta), B.1.526 (Iota), B.1.617.1 (Kappa) and P.2 (Zeta) are no longer VOC or VOI and therefore no longer included in the table. As of 29 March 2022, the same applies to B1.1.7 (Alpha), B.1.621 (Lambda) and C.37 (Mu).

* The figures for BA.1, BA.2, BA.3, BA.4, BA.5 have also been included in the total figures for the Omicron variant (B.1.1.529).

* The figures for BA.2.12.1, BA.2.75, BA.4.6 and the respective sub-variants BF.7, BQ.1, BQ.1.1 and XBB.1.5 have also been included in the total figures for the Omicron variant (B.1.1.529). Figures for BQ.1.1. have also been included in BQ.1.

# Variants BA.4.6, BF.7 and XBB have not yet been classified as VOC or VOI (by WHO and ECDC). However, these variants are classified as VUM and have been included in the table due to the recent increase and for the purpose of early detection.

When assessing the risks of a virus variant, it is important to know how contagious the variant is and how easily it spreads. Once there are more cases involving a specific virus variant, RIVM can calculate the reproduction number for that variant. The R number represents the number of people infected by someone who has the virus. It shows how quickly a specific variant can spread. 

​​​​​​From 4 January 2023 on, the Saltro data is no longer available due to decreases in the number of tests and changes in public contracts.

Alpha variant, B.1.1.7

The Alpha variant of the coronavirus, first found in the UK, was also detected in the Netherlands in December 2020. The Alpha variant then became the dominant strain in the Netherlands, supplanting the former variant of the virus. In summer 2021, the Alpha variant was ‘pushed out’ by the more contagious Delta variant.

Beta variant, B.1.351

The Beta variant of the coronavirus, first found in South Africa, was detected in the Netherlands in early January 2021. This variant of the virus, like the Alpha variant, also appears to be more contagious than the variant that had been dominant in the Netherlands until that point. The Beta variant is no longer detected in pathogen surveillance.

Gamma variant, P.1

The P.1 Gamma variant of the coronavirus was found mainly in outbreaks in and around Manaus, the capital of the Brazilian state of Amazonas. It is not yet clear whether the course of illness is different for this variant. Among other mutations, the variant has three changes in the spike protein, the lines bristling out from the coronavirus, that are considered cause for concern. These three changes are almost identical to the changes in the Beta variant. The immune response due to vaccination or due to previous infection with the virus may possibly be less effective against this variant.  The P.1 Gamma variant is currently no longer detected in pathogen surveillance.

Delta variant, B.1.617.2

The B.1.617.2 variant of the coronavirus was first found in October 2020 in India. In summer 2021, the Delta variant (B.1.617.2) replaced the Alpha variant as the dominant strain in the Netherlands. The Delta variant is much more contagious than the Alpha variant. The COVID-19 vaccines are effective in preventing hospital and ICU admissions, even against the Delta variant. At the end of 2021, the Delta variant was in turn replaced by the Omicron variant B.1.1.529. The same trend is occurring all over the world.

Emergence of Omicron variant B.1.1.529

The first cases involving the Omicron variant (B.1.1.529) of the coronavirus SARS-CoV-2 were reported in South Africa at the end of November 2021. The percentage of cases involving the Omicron variant rose rapidly around the world. Similar to other variants, the small changes (mutations) in this new variant were seen mainly in the lines bristling out from the coronavirus: the spike protein. A striking feature of this variant was that it proved to have an unusually large number of mutations in the spike protein. Never before had a new variant of the coronavirus spread as quickly as the Omicron variant. It became apparent that vaccine effectiveness against Omicron infection without booster vaccination was considerably lower compared to the Delta variant.
 

Frequently asked questions

How can you tell which variant of the coronavirus someone has?

If you test positive for COVID-19, the test results do not tell you which coronavirus variant you have. When analysing a COVID-19 test, a laboratory technician cannot see which variant of the coronavirus SARS-CoV-2 caused the infection. This requires further research, known as sequencing. This means further investigation of the virus sample that was taken with a cotton swab in the nose and throat. Sequencing looks at the building blocks of the virus. By looking at how the virus is constructed, it is possible to recognise characteristic ‘building blocks’ of a variant. Sequencing is performed on random samples in the context of pathogen surveillance

Can the PCR tests accurately identify the Omicron variant?

Yes. Various laboratories, including the WHO Reference Laboratories at RIVM and Erasmus University Medical Center, have investigated this and confirmed that they do. The PCR tests detect the presence of small fragments of genetic material from the coronavirus SARS-CoV-2 in nasal and throat mucus. PCR tests are used to determine if you have the virus right now. If you test positive for COVID-19, the test results do not tell you which coronavirus variant you have. This requires further research, known as sequencing. This means further investigation of the virus sample that was taken with a cotton swab in the nose and throat. By looking at how the virus is constructed, it is possible to recognise characteristic ‘building blocks’ of a variant.

Do the self-tests also detect the Omicron variant?

Yes, antigen tests are also effective in detecting the Omicron variant. This also applies to the self-tests. Various laboratories have investigated this and confirmed that they are effective. RIVM has confirmed this for 6 self-tests; see also technical evaluation of SARS-CoV-2 self-test with Omicron variant and previous technical evaluation of the same self-tests with the wild-type virus.

A self-test is an antigen test which is suitable for home use. Antigen tests, like PCR tests, only check if you are carrying the virus at that moment. The test does not check which coronavirus variant you have. This requires further research. For that purpose, a new PCR test sample must be taken, which is then used for sequencing. This means further investigation of the virus sample that was taken with a cotton swab in the nose and throat. Sequencing looks at the building blocks of the virus. By looking at how the virus is constructed, it is possible to recognise characteristic ‘building blocks’ of a variant.

Are the virus variants also being found in coronavirus monitoring in sewage?

Yes. Sewage samples are also analysed to check for the presence of different variants of the coronavirus SARS-CoV-2.