Tuesday, January 18

Pfizer injection is less effective in South Africa after the rise of Omicron: study


Pfizer-BioNTech’s Covid-19 vaccine has been less effective in South Africa at keeping people infected with the virus out of hospital since the Omicron variant emerged last month, a real-world study published Tuesday showed.

Between November 15 and December 7, people who had received two doses of the injection had a 70% chance of avoiding hospitalization, up from 93% during the previous wave of Delta infections, the study showed.

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When it came to avoiding infection altogether, the study by South Africa’s largest private health insurance administrator, Discovery Health, showed that protection against the capture of Covid-19 had plummeted to 33% from the previous 80%.

The real-world analysis findings are some of the first about the protection offered by vaccines against Omicron outside of laboratory studies, which have so far shown a reduced ability to neutralize the virus.

The study results were based on an analysis by Discovery’s actuarial and clinical research teams in collaboration with the South African Medical Research Council (SAMRC).

South Africa alerted the world to Omicron in November, sparking alarm that it could cause another spike in global infections and lead to travel restrictions in southern Africa. Since then, South Africa’s daily infections have risen to more than 20,000, with 35% of tests showing positive results in the figures reported Tuesday, and another 600 hospital admissions and 24 deaths.

The South African study was based on more than 211,000 Covid-19 test results, of which 78,000 were attributed to Omicron, the variant labeled “concerning” by the World Health Organization and reported in more than 60 countries. .

The 78,000 cases were attributed to Omicron based on the relative prevalence of the variant within the country during the study period, but because they have not been confirmed as the new variant, the study cannot offer conclusive findings.

South African scientists submitted 630 positive Covid-19 tests for genome sequencing in November to see if they were Omicron and another 61 so far in December. Last month 78% were confirmed as Omicron and 61 this month was the new variant.

‘Confusion factor’

Discovery cautioned that the study’s findings should be considered preliminary.

Michael Head, senior researcher in global health at the University of Southampton, also said that, for now, there is a high degree of uncertainty about Omicron.

“It is important to avoid inferring too much right now from any national scenario. For example, the narrative in South Africa is that Omicron can be much softer, while reports from Denmark generally suggest otherwise, ”he said.

South Africa is using the Pfizer-BioNTech and Johnson & Johnson vaccines in its immunization campaign, with more than 20 million doses of Pfizer administered so far.

J&J and SAMRC are conducting a large, real-world study of the J&J vaccine and a recent analysis has shown no deaths from Omicron, SAMRC President Glenda Gray said.

“So that’s the good news, it shows once again that the vaccine is effective against serious illness and death,” he said.

Given that at least 70% of the South African population is estimated to have been exposed to Covid-19 in the past 18 months, the estimated high levels of existing antibodies could skew the data.

“This could be a confounding factor for these indicators of severity and hospital admission during this wave of Omicron,” said Ryan Noach, executive director of Discovery Health, in a briefing on the study.

The analysis showed that protection against hospital admission was maintained at all ages, from 18 to 79 years, with slightly lower levels of protection for the elderly.

Protection against admission was also consistent in a variety of chronic diseases, including diabetes, hypertension, hypercholesterolemia, and other cardiovascular diseases.

Risk of reinfection

The study concluded that there was a higher risk of reinfection during the fourth wave than during previous ones and the risk of hospitalization among adults diagnosed with Covid-19 was still 29% lower than during the first wave of the country last year.

Children appeared to have a 20% higher risk of hospital admission with complications during the fourth wave than during the first, despite a very low absolute incidence, he said.

“These are initial data and require careful monitoring,” said Shirley Collie, chief actuary for health analysis at Discovery Health.

However, this trend aligns with a warning in recent days from South Africa’s National Institute of Communicable Diseases (NICD) that during the country’s third wave, from June to September, they had seen an increase in pediatric admissions and now, in the fourth wave, they are seeing a similar increase in admissions of children under the age of five, he said.

South African scientists have said they cannot confirm a link between Omicron and high baby admissions, which could be due to other factors.

Many unknowns still surround Omicron.

The WHO has said that there were early signs that vaccinated and previously infected people would not produce enough antibodies to protect themselves from an Omicron infection, resulting in high transmission rates, but it was unclear whether Omicron was inherently more contagious than the variant. Globally dominant delta.

Pfizer and BioNTech said last week that two injections of their vaccine can still protect against serious disease, because their mutations are unlikely to bypass the T-cell response.


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