South African health agencies report higher risk of Omicron re-infection


The latest variant of the Omicron coronavirus has a risk of re-infection three times higher than the dominant variant Delta and strain Beta, a group of South African health organizations said Thursday.

The South African Center for Epidemiological Modeling and Analysis (Sacema) and the National Institute of Communicable Diseases (NICD) said the latest findings “provide epidemiological evidence for Omicron’s ability to evade immunity against a previous infection “.

Their statement was released after a group of South African health organizations published an article on medrxiv.orgas a pre-print, meaning the work was not yet peer-certified.

Earlier today, NICD microbiologist Anne von Gottberg echoed the same views at an online press conference hosted by the World Health Organization. She said South Africa was seeing an increase in re-infections from Omicron.

South Africa has seen a sudden surge in daily infections, with the government reporting an additional 11,535 cases on Thursday, up from 312 just 10 days ago.

The NICD said on Wednesday that the Omicron variant was able to bypass some immunity and was quickly becoming the dominant strain in the country. The NICD, alongside a larger network of healthcare organizations, performs genome sequencing on samples.

Risk profile for reinfection

An analysis of routine surveillance data in South Africa from March 2020 to November 27 showed that “the risk profile for reinfection of Omicron is significantly higher than that associated with the Beta and Delta variants during the second and third waves. “, According to the NICD.

An increase in re-infections rather than new infections would be an indication that the latter variant has developed the ability to evade natural immunity from a previous infection, he said.

Juliet Pulliam, director of Sacema and author of the preprinted document, said in her article that the Omicron model is expected to be established in all provinces of South Africa by early to mid-December, noted the NICD.

The analysis is based on 2,796,982 people with positive test results at least 90 days before November 27, of whom 35,670 were suspected re-infections, he added.

South Africa has stepped up its vaccination campaign by giving injections at ephemeral sites in shopping malls and transport hubs to combat the rapid rise in new cases, a week after the discovery of the Omicron variant.

Scientists have said they are ready for the push to continue.

Gauteng province, home to South Africa’s largest city, Johannesburg, and the capital, Pretoria, is a hotspot for new infections, accounting for more than 70% of new cases.

Gauteng officials have said they are “preparing for the worst” by increasing hospital beds and reopening some field hospitals in anticipation of increased admissions of Covid-19 patients.

Tests indicate that the Omicron variant, first reported in southern Africa, is spreading rapidly and is now found in five of South Africa’s nine provinces. It is not known how many new daily cases Omicron involve, as scientists can only perform complete genetic sequencing on a small number of positive tests.

But it appears that Omicron is “quickly becoming the dominant variant” in South Africa, according to a statement released by the NICD. The institute said that 74% of the 249 samples sequenced in November were identified as Omicron.

Is it more contagious?

In October, before Omicron’s discovery, the Delta variant was the dominant form of coronavirus in South Africa.

Scientists in South Africa and around the world are genetically sequencing samples of Omicron to learn more about the variant.

Much remains unknown about the strain, including whether it is more contagious, as some health officials suspect, whether it makes people more seriously ill, or whether existing vaccines are effective against it.

In a separate development, scientists believe they may have found the “trigger” behind the rare blood clot complications resulting from the AstraZeneca vaccine.

According to an international team of researchers from Cardiff and the United States, the reaction can be attributed to how the adenovirus used in the vaccine to carry coronavirus genetic material into cells binds to a specific protein in the blood, known as platelet factor 4 (PF4).

Researchers believe this may trigger a chain reaction in the immune system that can lead to the development of blood clots – a condition known as vaccine-induced immune thrombotic thrombocytopenia (VITT). – Reuters / AP