People are more easily reinfected with omicron, study finds

How does omicron compare to other variants?

What You Should Know 3:43

(CNN) -

Researchers in South Africa reported Thursday that they found some evidence that people who had been infected once with the coronavirus were more likely to be re-infected with the omicron variant than with the beta or delta variants.

They said it's too early to know for sure, but a recent spike in second infections tells them that omicron is more likely to reinfect people.

• This is how omicron was discovered in South Africa, the variant of coronavirus that set off a chain reaction

"Contrary to our expectations and experience with previous variants, we are now experiencing an increased risk of reinfection that exceeds our previous experience," Juliet Pulliam, director of the South African Center for Epidemiological Analysis and Modeling at Stellenbosch University, said in a statement. (SACEMA) and who helped lead the study team.

Ómicron was identified in November, but it has concerned the World Health Organization and other global health officials, who have designated it as a variant of concern due to its many mutations affecting areas associated with transmissibility and the ability to evade the immune system.

Pulliam and his colleagues looked at reports of infections of 2.7 million people in South Africa since the pandemic, including more than 35,000 people who had COVID-19 more than once.

advertising

"We identified 35,670 people with at least two suspected infections (as of November 27, 2021), 332 people with a third suspected infection, and one person with four suspected infections," they wrote in their report published online in a preprint, which means that it has not been peer-reviewed or published in a medical journal.

"Among people who had more than one reinfection, 47 (14.2%) experienced their third infection in November 2021, suggesting that many third infections are associated with transmission of the omicron variant."

Will omicron make us restart our fight against the pandemic?

3:24

They are assuming the recent increase in cases in South Africa and the spread of omicron and not some other factor such as declining immunity.

The people whose cases they describe have not had the virus sequenced, so it is not certain that they were infected with the omicron variant.

However, officials say the omicron variant is now the dominant coronavirus variant in South Africa, accounting for 74% of the samples that were gene-sequenced in November.

More sequences are underway to determine the true prevalence of the variant.

• Mexico confirms the first case of the omicron variant of coronavirus

"The timing of these changes strongly suggests that they are driven by the appearance of the omicron variant," the researchers wrote.

Before omicron, the delta variant had been the most prevalent variant in South Africa and remains the dominant variant globally.

More data should make it clear if omicron is, in fact, driving reinfections in South Africa.

Public health officials should know by mid-December, they said.

"Population-level evidence suggests that the omicron variant is associated with a substantial ability to evade immunity from a previous infection. In contrast, there is no epidemiological evidence in the entire population of immune escape associated with beta or delta variants." they wrote.

This finding has important implications for public health, especially in countries like South Africa, where there are high rates of immunity to previous infections.

This study did not take into account vaccination nor could it explain the possible decline in immunity over time.

"Our most urgent priority now is to quantify the extent of omicron's immune escape for natural and vaccine-derived immunity, as well as its relative transmissibility to other variants and its impact on disease severity," Harry Moultrie said in a statement. , a senior medical epidemiologist with the Tuberculosis Center of the National Institute of Communicable Diseases of South Africa and a co-author of the article.

South African doctor explains how are the cases of the omicron variant 0:45

Immunity from infection vs.

immunity by vaccination

Michael Head, senior researcher on global health at the University of Southampton, said the situation may be different when it comes to immunity to vaccines.

• Even with the new omicron variant, vaccines are still the best solution and these are the reasons

"The immune response to vaccination is much stronger compared to immunity acquired by infection. While there is likely to be some impact, it is likely that it will still provide some level of protection," Head said in a statement to the Science Media Center at the United Kingdom.

"The booster dose may be key here to maintain a high level of protection."

"While we wait for more data to emerge in the coming days and weeks, the message to the general public should be: go get all the doses you are eligible for. Keep protection as high as possible."

The findings may mean that natural infection won't help build herd immunity, some experts said.

"Omicron has blown a big hole in the controversial argument that we should simply allow the infection to spread in an attempt to build immunity," microbiologist Simon Clarke of the UK's University of Reading said in a statement.

"We await a new indication as to whether omicron has any ability to evade vaccine-induced immunity."

Ómicron could cause 50% of coronavirus cases in Europe 2:31

coronavirusCovid-19micron