Current knowledge about Omicron
Researchers in South Africa and around the world are conducting studies to
better understand many aspects of Omicron and will continue to share the
findings of these studies as they become available.
Transmissibility: It is not yet clear whether Omicron is more transmissible (e.g.,
more easily spread from person to person) compared to other variants, including
Delta. The number of people testing positive has risen in areas of South Africa
affected by this variant, but epidemiologic studies are underway to understand if
it is because of Omicron or other factors.
Severity of disease: It is not yet clear whether infection with Omicron causes
more severe disease compared to infections with other variants, including
Delta. Preliminary data suggests that there are increasing rates of hospitalization
in South Africa, but this may be due to increasing overall numbers of people
becoming infected, rather than a result of specific infection with Omicron. There
is currently no information to suggest that symptoms associated with Omicron
are different from those from other variants. Initial reported infections were
among university students—younger individuals who tend to have more mild
disease—but understanding the level of severity of the Omicron variant will take
days to several weeks. All variants of COVID-19, including the Delta variant that
is dominant worldwide, can cause severe disease or death, in particular for the
most vulnerable people, and thus prevention is always key.
Effectiveness of prior SARS-CoV-2 infection
Preliminary evidence suggests there may be an increased risk of reinfection with
Omicron (ie, people who have previously had COVID-19 could become
reinfected more easily with Omicron), as compared to other variants of concern,
but information is limited. More information on this will become available in the
coming days and weeks.
Effectiveness of vaccines: WHO is working with technical partners to
understand the potential impact of this variant on our existing countermeasures,
Researchers in South Africa and around the world are conducting studies to
better understand many aspects of Omicron and will continue to share the
findings of these studies as they become available.
Transmissibility: It is not yet clear whether Omicron is more transmissible (e.g.,
more easily spread from person to person) compared to other variants, including
Delta. The number of people testing positive has risen in areas of South Africa
affected by this variant, but epidemiologic studies are underway to understand if
it is because of Omicron or other factors.
Severity of disease: It is not yet clear whether infection with Omicron causes
more severe disease compared to infections with other variants, including
Delta. Preliminary data suggests that there are increasing rates of hospitalization
in South Africa, but this may be due to increasing overall numbers of people
becoming infected, rather than a result of specific infection with Omicron. There
is currently no information to suggest that symptoms associated with Omicron
are different from those from other variants. Initial reported infections were
among university students—younger individuals who tend to have more mild
disease—but understanding the level of severity of the Omicron variant will take
days to several weeks. All variants of COVID-19, including the Delta variant that
is dominant worldwide, can cause severe disease or death, in particular for the
most vulnerable people, and thus prevention is always key.
Effectiveness of prior SARS-CoV-2 infection
Preliminary evidence suggests there may be an increased risk of reinfection with
Omicron (ie, people who have previously had COVID-19 could become
reinfected more easily with Omicron), as compared to other variants of concern,
but information is limited. More information on this will become available in the
coming days and weeks.
Effectiveness of vaccines: WHO is working with technical partners to
understand the potential impact of this variant on our existing countermeasures,
