Real world analysis of Omicron outbreak in South Africa including vaccine effectiveness

Yesterday, our team at Discovery Health shared the first at-scale, real-world analysis of the Omicron outbreak in South Africa - including a look at the Pfizer-BioNtech vaccine’s effectiveness against this new variant.

Considering that South Africa is at the centre of an Omicron outbreak, we recognised the urgency and importance of sharing early insights with colleagues around the world.

I had the privilege of presenting our findings alongside Professor Glenda Gray, President of the South African Medical Research Council and Shirley Collie, Chief Health Analytics Actuary at Discovery Health (who leads the capable Health Informatics team comprising actuaries, data scientists and clinicians who carried out this analysis).

There were two components to our research:

• We partnered with world-leading researchers from the South African Medical Research Council to provide insights into the Pfizer-BioNTech vaccine effectiveness against (a) infection and (b) severe disease linked to Omicron infection.

This analysis included over 211,000 COVID-19 test results, 41% from adult members who had received two-doses of the Pfizer-BioNTech vaccine. Approximately 78,000 of these COVID-19 test results were attributed to Omicron infections, over the period 15 November to 7 December 2021.

• Second, we explored Omicron’s rate of spread; severity of illness; clinical manifestations; and the Omicron reinfection risk of people who have recovered from a prior COVID-19 infection.

Here’ a summary of our findings:

1. Vaccine effectiveness:

• Two-dose Pfizer-BioNTech vaccination provides 70% protection against severe COVID-19 complications requiring hospitalisation, and 33% protection against COVID-19 infection, during an Omicron driven wave of COVID-19.
• A test negative design methodology, our sample size and completion of three separate sensitivity analyses assures high statistical relevance for this analysis.

2. Reinfection risk:?The risk of reinfection with Omicron is significantly higher for people who have had COVID-19 in the past, relative to the risk of reinfection with the Beta and Delta variants.

3. Severity: On a fully risk-adjusted basis, the risk of hospital admission among adults diagnosed with COVID-19 is 29% lower for infection during this Omicron-driven fourth wave, relative to the D614G-led (first) wave, which took place in mid-2020.

4. Children: Despite very low absolute incidence, preliminary data suggests that children have a 20% higher risk of hospital admission in the Omicron-led fourth wave in South Africa, relative to the D614G-led first wave.

Please refer to our press release and full presentation to explore the greater detail and the fascinating and detailed charts shared in relation to our research.

Whilst these are incredibly important insights, they remain preliminary as they relate to very early Omicron data - from the first three weeks of the Omicron-driven wave - and may potentially change as the wave progresses. This data is also confounded by various factors, including the high sero-prevalence of COVID-19 antibodies (high percentage of individuals who have antibodies to COVID-19) within the South African population at large, following our country’s severe Delta wave earlier this year.

Vigilance and vaccination remain key to overcoming the pandemic

I truly hope that the mild Omicron COVID-19 illness currently evident in both the clinical settings and in our data will remain the defining narrative in weeks to come. That said, we cannot become complacent. Considering that Omicron is driving the most rapid community spread we’ve seen in any wave to date, there is a risk that this fourth wave may yet overwhelm our healthcare system by virtue of the sheer number of people likely to be concomitantly infected.

With this in mind, it is extremely encouraging and reassuring to know that full vaccination with the Pfizer-BioNTech vaccine still offers strong protection against serious illness linked to Omicron infection. Our findings reinforce calls for all eligible individuals to choose to be vaccinated, and to play a part in flattening the Omicron curve on a global basis. The slightly lower vaccine effectiveness we see against admission in the case of Omicron also emphasizes the importance of the third booster dose of the Pfizer-BioNTech vaccine - which will soon be available to older age groups, six months after their second dose, through the National Department of Health’s mass vaccination campaign.?

As we head into the Festive Season, I’d like to take the opportunity to urge adherence to the important non-pharmaceutical measures of mask wearing, social distancing, avoiding public gatherings - particularly indoor gatherings - and hygiene precautions. Notwithstanding, it is also important to be festive, de-stress if possible, and support local enterprise here in South Africa.

?Our teams will continue to monitor the progression of the fourth wave closely, and I will certainly share further insights with you in due course.