Omicron is less severe than delta variant and two Covid vaccine jabs give good protection, study suggests
First real-world study also finds that excess natural deaths are significantly lower than in previous waves
Omicron is likely to be 23 per cent less severe than delta with vaccines still offering good protection, the first major real-world study into the new variant has shown.
A study of more than 78,000 omicron cases in South Africa recorded between Nov 15 and Dec 7 also found that the Pfizer jab still offers 70 per cent protection against hospitalisation after two doses.
The research showed that, compared with the first Wuhan strain, the virus led to 29 per cent fewer admissions to hospital, with 23 per cent fewer hospital admissions compared with delta.
Far fewer people also needed intensive care from omicron, with just five per cent of cases admitted to ICU compared with 22 per cent of delta patients.
Experts at Discovery Health, South Africa’s largest private health insurer, who compiled the data, said that although there were high numbers of breakthrough infections in people who had been vaccinated, cases appeared to be less severe, which they said was also backed up by anecdotal evidence from doctors on the ground
Speaking at a briefing on Tuesday morning, Ryan Noach, the chief executive officer at Discovery Health, said: “You can see very clearly that in this omicron way the adult population has a 29 per cent lower risk of admission.
“If you look at the proportion of patients admitted to high care in ICU for severe illness, across the first three waves, the proportion of patients in high care and ICU collectively exceeds 30 per cent, goes up to 35 per cent, whereas you can see in this omicron period, only about 13 per cent.
“So the data is correlating with the anecdotal feedback. And so it's this early point we believe there is hope that the severity is lower.
“What is clear is that vaccinated individuals are experiencing milder infections in general. We are hearing it’s primarily the unvaccinated that are requiring admission and oxygen in hospital.
“You can see that the excess natural deaths are still significantly lower than in previous waves, despite the rapid growth in the number of infections during this omicron period.”
The study also found that children were much less likely to test positive than adults but that they were at a 20 per cent greater risk of hospitalisation. However, most cases in children were mild, with
symptoms such as a sore throat, nasal congestion and fever resolving in two to three days.
Discovery Health also teamed up with the South Africa Medical Research Council (SAMRC) to provide real-world insights into the Pfizer- BionTech vaccine effectiveness against omicron.
They found that effectiveness against infection dropped from 80 per cent to 33 per cent but offered 70 per cent protection against hospital admissions, which was maintained across age groups and chronic conditions. At the time of the study there had been no deaths.
'Heartening and encouraging results'
Prof Glenda Geray of SAMRC said: “ I think it's very heartening to see these results and release that vaccine effectiveness is still greater than 50 per cent. And so I think it's encouraging and again, the issue of boosting strategy may also mitigate the reduction in vaccine effectiveness.
“Vaccination is the single most important intervention. It is true we are seeing a linkage between the infections we are seeing and hospitilisations. The question is, is this due to a less virulent virus, or is this due to high levels of prior infection and vaccination?
“I think it’s too early for us to make that call but we can say that prior infection and vaccination are impacting on the reduction of admission and serious illness. And we’re seeing a shorter duration in hospitalisation. People who have been vaccinated are staying in hospital just 2.4 days.
“Most people who are in hospital are unvaccinated. We should be cautiously optimistic but we should continue to be vigilant.”
The study also showed that the odds of reinfection were lower than during Delta, suggesting that people who have suffered a delta infection may be better protected.
The researchers said that although excess natural deaths had increased in South Africa in recent weeks, they were still significantly lower than in previous waves.
