The SARS-CoV-2 virus that causes COVID-19 has undergone genetic mutations over time leading to the development of new variants of the virus.
Last updated: 8 July 2022
On this page:
- About COVID-19 variants
- Variant updates
- Detecting variants
- Delta variant
- Omicron variant
- COVID-19 Variants of Concern framework
All viruses, including SARS-CoV-2, the virus that causes COVID-19, change over time. Most changes have little to no impact on the virus’ properties. However, some changes may affect how easily the virus spreads, the disease severity, the ability of vaccines to prevent disease or the effectiveness of treatments, diagnostic tools, or other public health and social measures.
There are many different variants and those that have had changes to the virus’s properties are called “Variants of Interest” (VOI) and are monitored more closely. VOIs that change the way the virus behaves are called “Variants of Concern” (VOCs).
During late 2020, the emergence of variants that posed an increased risk to global public health prompted the characterisation of specific VOIs and VOCs, in order to prioritise global monitoring and research, and ultimately to inform the ongoing response to the COVID-19 pandemic.
The five main VOCs include Alpha (B.1.1.7), Beta (B.1.31), Gamma (P.1), Delta (B.1.617.2) and Omicron (B.1.1.529).
The World Health Organization (WHO) and its international networks of experts monitor changes to the virus so that if significant changes to the virus structure are identified that would necessitate an updated public health response, countries and the public can respond to the variant and try to prevent its spread.
The Ministry of Health regularly reviews recent international developments with respect to the identification of new COVID-19 variants or further details about the properties of already identified variants, and monitors characteristics of current circulating variants.
Regular updates on COVID-19 variants are published on the Science News page.
Whole-genome sequencing (WGS) is required to identify which variant a person is infected with. This is possible through PCR testing but not through rapid antigen testing (RAT). In New Zealand individuals arriving from overseas who have a positive RAT test are asked to have a follow-up PCR test so that WGS can be performed. This helps identify which new variants are arriving in the country.
Ongoing wastewater surveillance is also used to monitor the variants circulating in the community.
The Delta variant was first detected in late 2020 and was named a Variant of Concern by the WHO on 31 May 2021. As it was more transmissible than previous variants, Delta spread rapidly worldwide and became the main variant in most countries.
In August 2021, the Delta variant arrived in New Zealand. Delta posed very different challenges to earlier strains of COVID-19, with its rapid transmission, infectiousness and higher risk of needing hospital care. People who were not vaccinated were most at risk.
The nature of Delta created a significant challenge in New Zealand and required a whole of system response in a way that had not been encountered previously. In October 2021, the Director-General of Health commissioned an independent review into the Ministry’s response to the August 2021 Delta outbreak.
Read the about the Delta Response Rapid Review.
Once the Omicron variant arrived in New Zealand it replaced Delta as the predominant variant. The Delta variant has not been detected in Aotearoa New Zealand since 2 March 2022.
The proportion of Delta cases has significantly reduced over time and evidence suggests that Delta does not currently pose a significant risk to public health. The World Health Organization (WHO) considers Delta as a previously circulating Variant of Concern. Clusters of Delta infection are still occasionally reported in countries where WGS is routinely performed.
Omicron was first identified in mid-November 2021. The World Health Organization rapidly classified Omicron as a Variant of Concern due to the large number of mutations it contains.
Omicron is much more transmissible than previous variants of the COVID-19 virus, and like other variants, it continues to evolve. The Omicron variant has spread rapidly worldwide and is now the major variant in many countries.
Whilst still causing illness, a person is less likely to be severely ill if they contract Omicron rather than Delta. However, Omicron has resulted in many more people being hospitalised than at any other time in the pandemic. This is not because Omicron is very severe but because Omicron is more transmissible and so can cause many infections over a short period of time.
Omicron can still cause severe illness and even death, especially in unvaccinated people and people who are at risk of severe outcomes, such as elderly and those with severe underlying health conditions. However, a smaller proportion of people who are infected with Omicron end up hospitalised compared to people infected with Delta.
Omicron in New Zealand
Omicron was first detected in New Zealand in an international traveller who arrived in the country on 10 December 2021. Managed isolation was still being used at that time, so community spread of Omicron was not detected until mid-January.
Two Omicron sub-variants BA.1 and BA.2 were introduced into New Zealand around the same time. BA.2 became dominant during the first three months of 2022. In response to Omicron, the Ministry established a three phased approach in early March 2022.
New Omicron sub-variants BA.2.12.1, BA.4 and BA.5 were identified in travellers to New Zealand in late April 2022. These sub-variants are common overseas and their occurrence in New Zealand was expected. They are likely to gradually replace BA.2.
The Omicron subvariant BA.2.75 was detected in New Zealand for the first time on 1 July 2022 in two people who arrived in New Zealand.
BA.2.75 is a recently identified second generation subvariant of BA.2, the dominant variant circulating in New Zealand at this stage. Evidence on BA 2.75 transmissibility, immune evasiveness and severity is still preliminary and emerging.
BA.2.75 has some characteristics that looks like they may enhance its ability to evade immunity, similar to the BA.4 and BA.5 Omicron subvariants, and there is some early evidence overseas that it may be slightly more transmissible that BA.2. There is no current evidence that it leads to more severe disease, although assessing the evidence is at a very early stage.
Although the new variants of Omicron continue to emerge, there does not appear to have been a change in the severity of disease due to these variants. Therefore, the public health settings already in place to manage current Omicron variants are appropriate for managing the subvariants present in our community.
Vaccination and Omicron
The Omicron variant has a large number of changes to the spike protein which is the key the virus uses to gain access to cells. The spike protein is also the part of the protein, which is targeted by many vaccinations, including the Pfizer vaccination. Because of the changes to the virus, the Omicron variant is more resistant to the protection provided by the original Pfizer vaccine, which was developed against the original SARS-CoV-2 virus.
However, the Pfizer vaccine still provides good protection from infection from the Omicron variant. Vaccination also provides very good protection against developing severe disease if a person does become infected. Newer vaccines are being produced specifically for the Omicron variant, but these newer vaccines have not yet been approved and are not in commercial production at this stage.
Read more about COVID-19 vaccination.
Other protection measures
Using public health precautions remains important to continue to protect our communities against Omicron. As well as vaccination, early detection of cases and isolation, staying home if you’re sick, wearing a mask, hand hygiene, improving ventilation and physical distancing remain important.
Read more about protecting yourself and others from COVID-19.
New COVID-19 variants will continue to emerge and some of these will be classified as Variants of Concern (VOCs). The general pattern of evolution of the SARS-CoV-2 virus, is for more infectious variants to develop from those already circulating. Only variants with an advantage over the existing dominant variant will be able to out-compete it, which is why certain variants have become progressively more infectious. All of the variants of SARS-CoV-2 have had a similar severity, but it is possible that a more severe variant could appear.
To support Government preparedness and response efforts, the Ministry of Health has developed Aotearoa New Zealand’s Strategic Framework for COVID-19 Variants of Concern. The Strategic Framework considers five plausible peer-reviewed scenarios that reflect the likely characteristics of new variants, and carefully considers the approaches for each scenario.
Read more about the Strategic Framework for COVID-19 Variants of Concern.