Omicron seems to carry higher Covid reinfection risk, says South Africa

The Omicron variant of Covid-19 appears to be reinfecting people at three times the rate of previous strains, experts in South Africa have said, as public health officials and scientists from around the world closely monitor developments in the country where it was first identified.

As the EU’s public health agency warned that Omicron could cause more than half of all new Covid infections in Europe within the next few months, evidence was emerging, however, that vaccines still appear to offer protection against serious illness.

According to new evidence collected in South Africa by its National Institute for Communicable Diseases (NICD) the latest epidemiological evidence suggests that Omicron can evade immunity from infection with earlier variants and is causing reinfections at three times previous rates.

The South African Centre for Epidemiological Modelling and Analysis along with the NICD said the latest findings “provide epidemiological evidence for Omicron’s ability to evade immunity from prior infection”.

“We believe that previous infection does not provide protection from Omicron,” said Anne von Gottberg, an expert at the NICD.

In mid-November South Africa was reporting about 300 Covid cases a day. On Wednesday, it reported 8,561 new cases, up from 4,373 the day before and 2,273 on Monday.

Outlining early research into the newly emerged variant, Von Gottberg said doctors were seeing “an increase for Omicron reinfections [of Covid-19]”.

She said: “We believe the number of cases will increase exponentially in all provinces of the country. We believe that vaccines will still, however, protect against severe disease. Vaccines have always held out to protect against serious disease, hospitalisations and death.”

Scientists from the same institute have said initial data suggests that Omicron may provoke less severe illness than previous variants although that may be skewed by the fact that many of the first Omicron cases have been identified in younger individuals or detected in very recently screened travellers.

But even as South Africans have rushed to get vaccinated – nudged by President Cyril Ramaphosa’s warning on Sunday that stricter lockdowns may have to be imposed if vaccination rates don’t improve – Aslam Dasoo, of the Progressive Health Forum, warned that the recent increase in vaccinations may be insufficient.

“It’s not enough to make a dent in the fourth wave,” he told the country’s News 24 news channel. “The test positivity rate was 1% last Monday. And it is now in the double digits. We are in the teeth of the fourth wave. Everyone you know is a potential risk to you,” he said.

Doctors in Gauteng province said Covid patients were presenting with flu-like symptoms including a dry cough that could be treated at home.

On Tuesday, the epidemiologist Prof Salim Abdool Karim said current vaccines still provided high levels of protection against hospitalisation and death.

The emergence of Omicron has led to a steep rise in the number of people seeking vaccination.

As well as an exponential jump in case numbers, South Africa has seen a sharp increase in its case positivity rate – the number of those tested who test positive – in the same period, from 10.7% to 16.5%, with the positivity rate in Gauteng reaching 19%.

Even more worrying has been the hospitalisation rate in Gauteng, which jumped by 144% last week, doubling approximately every six days.

South Africa has reported close to 3m Covid infections during the pandemic and more than 89,000 deaths, the most on the African continent.

While most of the focus on Omicron has so far been on Gauteng province, there were indications that the Omicron variant was taking hold elsewhere in South Africa.

In Cape Town on Thursday morning, Dr Keith Cloete, the head of the Western Cape health department, announced that the country’s southernmost province had entered a new wave of Covid-19.

“The week-on-week percentage change in the seven-day moving average of new cases has been more than 20% for more than a week, indicating that we have officially entered a resurgence,” he said, adding: “A very large increase in absolute numbers is expected for the coming weeks.”

Although only 16 cases of Omicron have been positively identified in the province, Cloete said that based on a proxy marker in PCR tests, the Omicron variant could be prevalent in as much as 80% of the new cases in the last week.

And while much has been written about the issue of a lack of vaccines in the developing world, this has not been the main issue in South Africa.

For several months, supply there has outstripped demand and in late November the government asked Johnson and Johnson and Pfizer to delay the delivery of vaccines as they had too much stock.

The latest figures suggest about 36.3% of adults are fully vaccinated (although 64% of over-60s have had at least one dose). Vaccination, however, is lowest among younger age groups. Only 26% of South Africans between 18 and 34 – the cohort currently showing the highest rate of Omicron infections – have had one vaccine dose.