Omicron
Omicron cases today are at 2919 across 66 countries according to BlueDot (yesterday the tally was 2563 cases across 60 countries).
According to BlueDot today, Omicron is estimated to have an R-value between 3 and 3.5, similar to SARS-CoV-2 prior to vaccines in 2020. UK and Europe (ECDC) estimates are that in the next 2-4 weeks, the proportion of new cases which are Omicron will reach 50%.
Some observations from South Africa (source - Airfinity): An analysis of 166 hospitalised patients in the Tshwane District likely infected with Omicron, revealed a different age profile than what has been seen in previous waves, with 80% of hospitalised patients below the age of 50. This difference in age can possibly be explained by vaccine coverage, with 34% of the younger cohort being vaccinated in the province compared to 57% of those over 50. However, it may take 2-3 weeks longer to get a better understanding on the full impact across age groups as there is a 1-3 week lag between infection and hospitalisations.
The majority of those in non-ICU and High-Care wards in the Tshwane District are not receiving oxygen supplementation; this was determined to be a total of 21% of those hospitalised receiving oxygen for COVID-191. Previously, in January 2021, 63% of hospitalised patients under 65 years old in Wuhan were receiving oxygen; this may suggest the severity of disease in South Africa may be less than in previous waves.
No increase in deaths has been observed in South Africa at this point, but there is typically a 5 week lag in death rates behind case rates.
Even if Omicron is less severe, a large increase in cases, due to possible increased transmissibility, can still lead to an overall increase in hospitalisations, which could overwhelm health care systems.
Data released from the UK Health Security Agency provide an early estimate of the impact of Omicron on vaccine effectiveness. Estimated effectiveness of 2 doses against Omicron is reduced approx. 36% (AstraZeneca) and 29% (Pfizer) in comparison to Delta. However with a Pfizer booster, effectiveness is then improved by an estimated 66% (original AZ course) and 41% (original Pfizer course).
A private event (party) in Somerset England in which Omicron COVID-19 spread widely, had 78% of the samples analysed (14 of 18 attendees) test positive for Omicron – similarly, a bigger event in Norway (over 100 people) had all of those tested so far return results positive for Omicron (https://www.fhi.no/en/news/2021/preliminary-findings-from-outbreak-investigation-after-christmas-party-in-o/ ). At both events, attendees were required to be fully vaccinated and to have had a negative lateral flow test. Two very large events in UK and US have similar high rates of positivity for Omicron, and are still undergoing testing. (Source: Airfinity).
Other
On treatments, there is a real-world UK study being launched of molnupiravir given to high risk people upon diagnosis with COVID-19. Novartis is working on an antiviral active against all human coronaviruses. And also in the US the FDA has granted EUA for the AstraZeneca long-acting monoclonal antibody drug Evusheld as prophylaxis for immunosuppressed who don’t mount an adequate vaccine response.
On waning with CoronaVac, and improvement with boosters – Zeng et al: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00681-2/fulltext
The Airports Council International added its voice to calls for evidence-based travel measures: https://aci.aero/2021/12/09/governments-must-coordinate-and-implement-evidence-based-travel-measures/
Best wishes,
David Powell
IATA Medical Advisor