26 November 2021. WHO designated variant B.1.1.529 as a variant of concern under the name Omicron, as recommended by the WHO Technical Advisory Group on Virus Evolution (TAG-VE)? This decision was based on evidence presented to the TAG-VE that Omicron has several mutations that may affect its behavior, such as its ease of spread or the severity of the disease it causes. The following is a summary of what is currently known.
Current knowledge about Omicron
Researchers in South Africa and around the world are currently conducting studies to better understand many aspects of Omicron, and we will continue to share the results of these studies as they become available.
Infectivity: it is not yet clear whether Omicron is more infectious (i.e., more easily spread from person to person) than other variants, including Delta. The number of positive tests has increased in areas of South Africa affected by the variant, but epidemiological studies are ongoing to determine whether this is due to Omicron or other factors.
Disease severity: It is not yet clear whether Omicron infection causes more severe disease than infections caused by other variants, such as Delta virus. Preliminary data suggest an increase in hospitalizations in South Africa, but this may be due to an increase in the overall number of infected people rather than a specific Omicron virus infection. There are currently no data to suggest that the symptoms associated with Omicron are different from those associated with other variants. The first reported infections were in university students – younger people who tend to have milder disease – but understanding the severity of the Omicron variant takes days to weeks. All variants of COVID-19, including the globally distributed Delta variant, can cause serious illness or death, especially in the most vulnerable, so prevention is always important.
Efficacy of previous SARS-CoV-2 infection
Preliminary data suggest that the risk of re-infection with Omicron may be higher (i.e., people who have previously been infected with COVID-19 may be more likely to be re-infected with Omicron) than with other variants, but there is limited information on this. More information will be provided in the coming days and weeks.
Vaccine efficacy: WHO is working with technical partners to understand the potential impact of this variant on current responses, including vaccines. Vaccines remain essential to reduce serious morbidity and mortality, even against the prevailing strain in circulation, the Delta strain. Current vaccines are effective in preventing serious disease and death.
Effectiveness of current tests: commonly used PCR tests continue to detect infections, including Omicron infections, as has been the case with other variants. Whether this affects other types of tests, such as rapid antigen detection tests, is currently being investigated.
Effectiveness of current treatment Corticosteroids and IL6 receptor blockers remain effective in treating patients with severe COVID-19. Other therapies are being evaluated to determine whether they remain effective due to changes in the viral components of the Omicron variant virus.
WHO is currently working with a number of researchers around the world to better understand Omicron? Ongoing or planned studies will assess issues such as infectiousness, severity of infection (including symptoms), effectiveness of vaccines and diagnostic tests, and effectiveness of treatment.
WHO encourages countries to participate in the collection and sharing of data on hospitalized patients through the WHO COVID-19 clinical information platform to rapidly describe the clinical characteristics and treatment outcomes of patients?
More information will be available in the coming days and weeks. The WHO TAG-VE will continue to monitor and evaluate data as it becomes available and assess how Omicron mutations change viral behavior.
Recommended actions for countries
As Omicron has been identified as a variant of concern, WHO recommends that countries take a number of actions, including enhanced case surveillance and sequencing, sharing genome sequences in publicly available databases such as GISAID, reporting first cases or clusters to WHO: field studies and laboratory evaluations to better understand whether Omicron has other infectious or pathogenic properties or whether it has an impact on the effectiveness of vaccines, therapeutics, diagnostics or public health and social interventions. For more information, see the Communication of 26 November.
Countries should continue to implement effective public health measures to reduce the overall spread of COVID-19 through risk assessment and evidence-based approaches. They need to expand certain public health and medical capacities to cope with the increasing number of cases. WHO will provide support and guidance to countries on both preparedness and response?
It is also crucial that inequalities in access to COVID-19 vaccines are urgently addressed to ensure that the most vulnerable groups worldwide, such as health workers and the elderly, receive their first and second doses of the vaccine and that treatment and diagnosis are equally accessible.
Recommended actions for individuals
The most effective measures that people can take to limit the spread of COVID-19 are: keeping at least one meter away from other people, wearing a tight-fitting mask, opening windows to improve ventilation, avoiding poorly ventilated or confined spaces, keeping hands clean, coughing or sneezing into a bent elbow or handkerchief, and getting vaccinated when it is their turn.
WHO will continue to provide updates as more information becomes available, including after UNGAT meetings? In addition, information will be available on WHO digital platforms and social media.