Discovery Health, South Africa’s largest private health insurance administrator, releases at-scale realworld analysis of Omicron outbreak based on 211000 COVID-19 positive test results in South Africa, including collaboration with the SA Medical Research Council (SAMRC) to analyse vaccine effectiveness:
- Vaccine-effectiveness:
o Two-dose Pfizer-BioNTech vaccination provides 70% protection against severe
complications of COVID-19 requiring hospitalisation, and 33% protection against COVID19 infection, during the current Omicron wave. - Reinfection risk: For individuals who have had COVID-19 previously, the risk of reinfection
with Omicron is significantly higher, relative to prior variants. - Severity: Risk of hospital admission among adults diagnosed with COVID-19 is 29% lower for
Omicron variant infection compared to D614G infection in South Africa’s first wave in mid2020, after adjusting for vaccination status - Children: Despite very low absolute incidence, preliminary data suggest children have 20%
higher risk of hospital admission in Omicron-led fourth wave in South Africa, relative to
D614G first wave
It is important to note that these insights relate to data from the first three weeks of the Omicrondriven wave in South Africa, and consequently should be considered preliminary, and may change with extension of the wave. These data are also confounded by various factors, including high seroprevalence of COVID-19 antibodies in the South African population as a whole.
Omicron: A highly transmissible variant causing rapid community spread
The Omicron variant of SARS-CoV-2 was first identified in Southern Africa during November 2021,
brought to the attention of the world by scientists in South Africa and Botswana and declared a Variant of
Concern by the World Health Organization shortly thereafter. South Africa experienced rapid community
spread (concentrated in the Gauteng Province), dominated by the Omicron variant, fuelling South Africa’s
fourth wave of COVID-19.
“Superb genetic surveillance by the Network for Genomic Surveillance in South Africa identified that
Omicron infection accounts for over 90% of new infections in South Africa, and has displaced the
formerly dominant Delta variant,” says Dr Ryan Noach, CEO of Discovery Health, South Africa’s largest
private health insurer. “The Omicron-driven fourth wave has a significantly steeper trajectory of new
infections relative to prior waves. National data show an exponential increase in both new infections and
test positivity rates during the first three weeks of this wave, indicating a highly transmissible variant with
rapid community spread of infection.”
Real-world data relating to Omicron experience critical to guiding global response
With more than 3,7 million clients, Discovery Health has extensive claims data and private health system
utilisation data and is uniquely positioned to generate at scale real-world insights into the impact of
COVID-19. Ryan Noach explains: “There is a social responsibility to update and inform on Omicron given the urgency
nationally and globally; and we are in a unique position to do so, given the dominance of the Omicron
variant in SA and across Discovery Health’s administered medical scheme member base, and the richness
and significance of our data, spanning clinical records, vaccination records and pathology test results
drawn from our substantial database.”
Over the past month, Discovery Health’s clinical research and actuarial team have carried out the first atscale analysis of Omicron’s real-world impact.
• Discovery Health partnered with world-leading researchers from the South African Medical
Research Council (SAMRC) to provide insights into the vaccine effectiveness of the PfizerBioNTech vaccine against infections and severe disease linked to Omicron infection
• Discovery Health further explored various other components of Omicron infection including the
rate of spread; severity of illness relative to prior waves; clinical manifestations; and the relative
reduction of risk conferred by prior proven COVID-19 infection.
The detailed vaccine effectiveness analysis in collaboration with the SAMRC includes more than 211,000
positive COVID-19 test results, 41% from adult members who had received two-doses of the PfizerBioNTech vaccine. Approximately 78,000 of these positive COVID-19 test results were attributed to
Omicron infections, over the period 15 November to 7 December 2021.
“To-date laboratory analysis has provided early insights into potential reduction in the effect of
neutralising antibodies against the Omicron variant,” says Dr Noach. “However there remains urgency
around establishing real-world data on Omicron across all areas of impact. Our research into Omicron is
based on a rich and significant sample, and also relates directly to the experience of the first country in
the world to face a COVID-19 wave driven by Omicron,” says Dr Noach.
Findings:
(1) Two-dose Pfizer-BioNTech vaccination provides significant protection against hospitalisation in
individuals with Omicron variant infection Discovery Health’s research on the effectiveness of two-dose Pfizer-BioNTech vaccination in preventing severe disease and hospitalisation as a result of Omicron variant infection has been carried out by Discovery Health’s actuarial team in collaboration with leading scientists at the South African Medical
Research Council.
“We used a test-negative design methodology to establish the Pfizer-BioNTech COVID-19 vaccine’s realworld effectiveness against hospital admission from Omicron infection,” said Shirley Collie, Chief Health
Analytics Actuary at Discovery Health. “We carried out three carefully constructed sensitivity analyses
with consistent results across each analysis supporting the veracity of our findings. These findings were
reviewed by scientists at the SAMRC with whom we have collaborated on multiple areas of our
pandemic-related research to date.” The result shows that vaccinated individuals who received two-doses of the Pfizer-BioNTech vaccine have 33% protection against infection, relative to the unvaccinated, in the first weeks of South Africa’s
Omicron-driven fourth wave. This represents a significant drop from the 80% protection against infection
afforded during the earlier period, probably on the basis of lower antibody susceptibility, following the
extensive Spike Protein mutations in the Omicron variant.
Encouragingly though, the result shows that these same vaccinated individuals who received two-doses
of the Pfizer-BioNTech vaccine have 70% protection against hospital admission in this same time period.
Whilst protection against hospital admission reduced from the highs of 93% in South Africa’s Delta-driven
variant, 70% is still regarded as very good protection. President of the SAMRC, Professor Glenda Gray said, “We are extremely encouraged by the results of Discovery Health’s analysis. It is extremely important to be able to demonstrate to the public that in a real-world setting – in the presence of a highly transmissible new COVID-19 variant – the Pfizer-BioNTech vaccine provides good protection against severe disease and hospitalisation.”
Furthermore, the analysis demonstrates that protection against hospital admission is maintained across
all ages, in people from 18 to 79 years, with slightly lower levels of protection for the elderly (67% in
people aged 60 to 69 and 60% for people aged 70 to 79). Protection against admission is also consistent
across a range of chronic illnesses including diabetes, hypertension, hypercholesterolemia, and other
cardiovascular diseases.
(2) Omicron reinfection risk significantly higher compared to prior variants
“With each successive wave of COVID-19 infection in South Africa, we have investigated the durability of
immunity following previous infection with COVID-19 – i.e., the risk of reinfection,” explains Shirley Collie,
Chief Health Analytics Actuary at Discovery Health.
“Overall, the risk of re-infection following prior infection has increased over time, with Omicron resulting
in significantly higher rates of reinfection compared to prior variants.”
- People who were infected with COVID-19 in South Africa’s third (Delta) wave face a 40% relative
risk of (re)infection with Omicron. - People who were infected with COVID-19 in South Africa’s second (Beta) wave face a 60%
relative risk of (re)infection with Omicron.
“While individuals who had a documented infection in South Africa’s first wave, and therefore were likely
to have been infected with the D614G SARS CoV-2 virus, face a 73% risk of reinfection relative to those
without prior documented infection.” adds Collie.
(3) Risk of severe disease and hospitalisation significantly lower in Omicron infection compared to
prior variants
Discovery Health has investigated the Omicron variant’s clinical impact relative to other SARS-CoV-2
variants. “Epidemiological tracking shows a steep trajectory of new infections, indicating Omicron’s rapid spread,
but so far with a flatter trajectory of hospital admissions, possibly indicating lower severity,” explains Dr
Noach. “This lesser severity could however be confounded by the high seroprevalence levels of SARS
CoV-2 antibodies in the general South African population, especially following an extensive Delta wave of
infections.”
Collie adds, “Adults are experiencing a 29% lower admission risk relative to South Africa’s first wave of
infection, dominated by D614G, in early 2020. Furthermore, hospitalised adults currently have a lower
propensity to be admitted to High care and Intensive Care Units, relative to prior waves”
(4) Preliminary observations on Omicron experience in children
“Notwithstanding the fact that children continue to show a very low incidence of severe complications
following COVID-19, Discovery Health’s data indicate that children under age 18 have 20% higher risk of
admission for complications of COVID-19, when infected with Omicron,” says Collie. “This is early data
and requires careful follow up. However, this trend aligns with the South Africa’s National Institute for
Communicable Diseases (NICD) warning in recent days that during South Africa’s third wave of infection
(June to September 2021) they had seen an increase in paediatric admissions and now, in the fourth
wave, they are seeing a similar increase in admissions for children under five. Anecdotal reports from
hospitals in South Africa indicate that most COVID-19 diagnoses in children admitted to hospital are coincidental – many children that are admitted for non-COVID related conditions, and are not experiencing
COVID-19 complications, test positive for COVID-19 on routine screening tests.”
It is also important to note that Discovery Health’s analysis shows that the risk of children testing positive
for COVID-19 infections was significantly lower than in adults. “Children were 51% less likely to test
positive for COVID-19 relative to adults in the Omicron period, and overall, the risk of children being
admitted to hospital for COVID-19 complications remains low,” Collie adds.
Where children require admission for complications of COVID-19, the primary diagnoses are bronchiolitis
and pneumonia, often with severe gastrointestinal symptoms and dehydration.
“The majority of children present with mild disease with symptoms such as a sore throat, nasal
congestion, headache and fever which resolves within three days,” adds Dr Noach, based on anecdotal
consensus sourced from the treating healthcare professionals.
Vigilance and vaccination remain our primary means of overcoming the pandemic
“We are encouraged that the Pfizer-BioNTech vaccine continues to offer high levels of protection from
severe COVID-19 illness,” said Dr Noach. “We are hopeful that the current experience of COVID-19 caused by the Omicron variant – mild disease for the most part – will remain unchanged. Notwithstanding this, we remain concerned that health systems could still come under pressure considering the high rate of spread of Omicron, and consequent
high sudden infection burden. Our research teams will continue to monitor the progression of the fourth
wave in this regard, and we will depend on the continued stewardship of the National Department of
Health to ensure health systems can cope with the disease burden.”
“The importance of COVID-19 vaccination in the current context is unquestionable, as conclusively
demonstrated in the research. At the same time, we urge adherence to the important nonpharmaceutical measures of distancing, avoiding public gatherings, mask wearing and hygiene
precautions.”
“We extend our sincere thanks to all the healthcare professionals, scientists and support staff working on
the pandemic’s frontlines, delivering outstanding care and giving their all to bring our country and the
world closer to overcoming the COVID-19 pandemic.”
