Three Longs & Three Shorts

Omicron SARS-CoV-2 variant: a new chapter in the COVID-19 pandemic

Author: Salim S Abdool Karim, Quarraisha Abdool Karim
Source: The Lancet ( )

Whilst it is early days for us to have a definitive view on the new Covid variant – Omicron, we are all eager to know what the pandemic has in store for us. True to the social media driven information age we live, there’s plenty of hyperbole and propaganda from both sides of the debate. The Lancet produced an objective take on what we know about it so far – particularly about the three key questions about Omicron – is it more infectious, is it more deadly and will vaccines be of any use? The article acknowledges that it will be weeks before more data emerges from studies across the world for us to form a definitive view on the variant. But here’s what we know so far:
On transmissibility:
“The impact of omicron on transmissibility is a concern. If the overlapping omicron mutations maintain their known effects, then higher transmissibility is expected, particularly because of the mutations near the furin cleavage site. Early epidemiological evidence suggests that cases are rising in South Africa and that PCR tests with S-gene target failure are also rising. Although omicron is likely to be highly transmissible, it is not yet clear whether it has greater transmissibility than delta, although preliminary indications suggest that it is spreading rapidly against a backdrop of ongoing delta-variant transmission and high levels of natural immunity to the delta variant. If this trend continues, omicron is anticipated to displace delta as the dominant variant in South Africa.”
On severity:
“We await knowledge of how this new VoC will impact clinical presentation. At this stage, the available anecdotal data from clinicians at the front lines in South Africa suggest that patients with omicron are younger people with a clinical presentation similar to that of past variants.13 Although no alarming clinical concerns have been raised thus far, this anecdotal information should be treated with caution given that severe COVID-19 cases typically present several weeks after the initial symptoms associated with mild disease.”
On effectiveness of vaccines:
“Immune escape is another concern. In the absence of data on observational vaccine effectiveness and antibody-neutralisation studies on vaccinee sera, preliminary data from the national PCR testing programme could provide some clues. Data on positive PCR tests in people with previous positive tests suggest an increase in cases of reinfection in South Africa. However, the increased use of rapid antigen tests and incomplete capturing of negative results have complicated the interpretation of test positivity rates, which have risen to about four times the previous rate in the past week. Notwithstanding this limitation, the increase in cases of reinfection is in keeping with the immune-escape mutations present in omicron.”