The Omicron variant is three times more likely to cause reinfection in humans, compared to earlier variants of the coronavirus, new data from South Africa suggests.
The study, released Thursday, is the first strong indication of why Omicron has grown so rapidly in countries like South Africa, where a large percentage of the population has reportedly developed immunity to COVID-19 as a result. from a previous infection.
This has huge implications for countries such as India and many African countries with low vaccination rates, where immunity has been achieved largely through infection. Even though the new variant is not more transmissible than other variants, such as Delta, it could still spread faster because people are more vulnerable to it, scientists say.
“It’s the susceptibility of the population that is greater now,” said Anne von Gottberg of the National Institute of Communicable Diseases (NICD) in South Africa, one of the authors of the preprint study.
“The previous infection protected against Delta, and now with Omicron that doesn’t appear to be the case,” she said during a briefing at the World Health Organization’s African office.
Vaccines will be the best weapon against the new variant, scientists say. Vaccines have the potential to protect people against serious illness, hospitalizations and death from the Omicron variant, Professor von Gottberg said during the briefing.
It is too early to know the severity of Omicron’s cases, although so far there is no indication that it is causing more serious illness.
South Africa, the first country to detect and report it to the WHO last week, is emerging as the world’s hotspot for the variant, with more confirmed cases than any other country.
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Omicron is behind a dramatic increase in infections in South Africa, and around three-quarters of new cases are believed to involve the new variant, based on laboratory sequencing of the samples.
Health authorities on Thursday reported more than 11,500 new cases in South Africa. The number has nearly tripled in the past two days and has quintupled since Monday.
The daily positivity rate doubled to 22% in the same four-day period, meaning more than a fifth of tests detect cases of the virus. The positivity rate was less than 2% in mid-November.
The vast majority of cases are found in the economic heart of South Africa, the province of Gauteng, where Johannesburg and Pretoria are located. The surge in Gauteng is steeper and faster than any previous wave, forcing scientists to recalibrate their projection models. Hospitalizations there have also increased, but not as sharply as the increase in cases.
Many countries around the world have praised South Africa for detecting and identifying the new variant as quickly and transparently as it has, but have also imposed strict bans on travelers from Africa. South, inflicting considerable damage on the country’s tourism industry.
The preprint study is based on the test results of 2.8 million South Africans who had confirmed cases of the virus in the past three months. Data shows the risk of re-infection has tripled since early October as the new variant took hold. The study is considered a pre-publication because it has not been peer reviewed.
“Population-level evidence suggests that the Omicron variant is associated with a substantial ability to evade immunity against previous infection,” the study concluded.
He said the data suggests that the “selection advantage” of the new variant “is at least partially driven by an increased ability to infect previously infected individuals.”
With the emergence of Omicron, South African leaders have stepped up their efforts to persuade people to get vaccinated. The message seems to be working. This week, an average of 165,000 people per day were vaccinated, an increase of about 30% from last week. The authorities are trying to speed up the campaign by setting up new vaccination sites in shopping malls, high schools and transport poles.
More than 36% of South African adults have been fully immunized so far. The rate is high compared to most other African countries but lower than in richer countries, mainly due to long lead times for vaccine supply.
President Cyril Ramaphosa has announced that the government will consider making vaccines a mandatory rule for access to certain places and activities, although no details have been decided so far. A growing number of businesses and unions have expressed support for the immunization mandates.
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