Discovery Health publish its first Omicron data - here are 4 important findings.
By Lehlohonolo Lehana.
Discovery Health, South Africa’s largest private health insurance administrator, has published its first data on the Omicron variant and its early impact on the country.
In a presentation on Tuesday (14 December), the group noted that its data was taken from the first three weeks of the Omicron-driven wave in South Africa. Therefore, the insights should be considered preliminary, since they may change as the wave progresses.
Discovery said that various factors, such as the high rate of Covid-19 antibodies in the South African population as a whole, should also be taken into consideration.
"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," said Dr Ryan Noach, chief executive of Discovery Health.
"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."
With more than 3.7 million clients, Discovery Health has extensive data relating to claims and the utilisation of the private health system. Therefore, Discovery Health is uniquely positioned to generate at-scale, real-world insights into the impact of Covid-19, Noach said.
"There is a social responsibility to update and inform on Omicron given the urgency on this front, nationally and globally."
"We are in a unique position to do so, given the dominance of the Omicron variant in South Africa and across Discovery Health’s member base of administered medical schemes, and the richness and significance of our data, spanning clinical records, vaccination records and pathology test results drawn from our substantial database."
Here are four key findings from Discovery’s early data.
Vaccine effectiveness is reduced – but still the best line of defence
The data shows that the two-dose Pfizer-BioNTech vaccination provides significant protection against hospitalisation in individuals with an 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 was 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 real-world 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 in multiple areas of our pandemic-related research to date."
The result shows that vaccinated individuals who received two doses of the Pfizer-BioNTech vaccine had 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 had 70% protection against hospital admission in this same time period.
While protection against hospital admission reduced from the highs of 93% in South Africa’s Delta-driven wave, 70% is still regarded as very good protection.
Furthermore, the analysis shows 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.
Omicron reinfection risk is 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 the previous infection with Covid-19 – in other words, the risk of reinfection," said Collie.
"Overall, the risk of re-infection has increased over time, with Omicron resulting in significantly higher rates of reinfection compared to prior variants."
The data shows that
- People who were infected with Covid-19 in South Africa’s third (Delta) wave face a 40% relative risk of reinfection with Omicron.
- People who were infected with Covid-19 in South Africa’s second (Beta) wave face a 60% relative risk of reinfection 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 SARS CoV-2 virus carrying the D614G mutation, face a 73% risk of reinfection relative to those without prior documented infection, said Collie.
Risk of severe disease and hospitalisation significantly lower in Omicron infection compared to prior 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," said 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 added that 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,"he said.
Bigger impact on children
Notwithstanding the fact that children continue to show a very low incidence of severe complications following Covid-19, Discovery Health’s data indicates that children under age 18 have a 20% higher risk of admission for complications of Covid-19 when infected with Omicron, said Collie.
"This is early data and requires careful follow-up. However, this trend aligns with the warning from South Africa’s National Institute for Communicable Diseases (NICD) in recent days that during South Africa’s third wave of infection 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 years of age."
"Anecdotal reports from hospitals in South Africa indicate that most Covid-19 diagnoses in children admitted to hospital are co-incidental – many children who are admitted for non-Covid-19-related conditions, and who 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 is significantly lower than in adults, he said.
"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 said.
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 that resolves within three days," Noach added, based on anecdotal consensus sourced from the treating healthcare professionals.