South African scientists have criticised developed nations for ignoring early evidence that Omicron was “dramatically” milder than the previous strains of the coronavirus, an attitude which could be construed as “racism”.
“It seems like high-income countries are much more able to absorb bad news that comes from countries like South Africa,” said Prof Shabir Madhi, vaccinologist at Wits University.
“When we’re providing good news, all of a sudden there’s a whole lot of scepticism. I would call that racism.”
Prof Salim Karim, former head of the South African government’s COVID advisory committee and vice-president of the International Science Council concurs.
“We need to learn from each other. Our research is rigorous. Everyone was expecting the worst and when they weren’t seeing it, they were questioning whether our observations were sufficiently scientifically rigorous,” he said, though he acknowledged that Omicron’s high number of mutations may have led to an overabundance of caution.
But by early December, anecdotal evidence was already indicating that Omicron caused far fewer hospitalisations than the Delta Wave, despite being more transmissible.
“The predictions we made at the start of December still hold. Omicron was less severe. Dramatically. The virus is evolving to adapt to the human host, to become like a seasonal virus,” said Prof Marta Nunes, senior researcher at the Vaccines and Infectious Diseases Analytics department at Wits
“It didn’t take even two weeks before the first evidence started coming out that this is a much milder condition. And when we shared that with the world there was some scepticism,” Prof Karim added.
While some have argued that Africa’s pandemic experience is different due to factors such as its younger population, any advantage South Africa has is outweighed by poor health, with excess deaths during COVID at 480 per 100 000, one of the highest in the world. Prof Madhi points out a high prevalence of comorbidities such as obesity and HIV.
A majority of those excess deaths are probably due to the pandemic, many SA scientists believe. Half occurred during the Delta wave, but only 3% transpired during the Omicron wave so far, Prof Madhi pointed out.
The government chose not to tighten restrictions during the fourth wave, and criticised the reimposition of travel bans coming from South Africa. South African scientists have mostly welcomed this, even though the WHO continues to warn that Omicron should not be considered “mild”.
“We believe the virus is not going to be eradicated from the human population. We must now learn how to live with this virus and it will learn how to live with us,” said Prof Nunes.
The low death rate from Omicron indicates a different phase of the pandemic. “I’d refer to it as a convalescent phase,” said Prof Madhi. The government has already effectively stopped quarantining and contact tracing.
With the Omicron variant now dominating, a local study showed that, if confirmed, testing for COVID could be more accurate with much easier saliva sampling.
University of Cape Town researchers reported in a paper uploaded to medRxiv[PDF] that in Omicron cases, saliva samples yielded more accurate results in PCR analyses compared to nasal swabs.
With the Delta variant, on the other hand, nasal swabs were more accurate, according to the group, led by Diana Hardie, MBChB, MMedPath, who also heads the diagnostic virology laboratory at Groote Schuur Hospital.
The findings came from an analysis of 382 patients tested at Groote Schuur from August through this month, with viral whole-genome sequencing performed on isolates from those with positive results.
All patients had both saliva and mid-turbinate nasal samples taken for RT-PCR analysis. The ‘gold standard’ for positivity in the study was detection of SARS-CoV-2 RNA with either swab.
For the Delta variant, the positive percent agreement for each sampling method, in comparison with this ‘gold standard’, was 71% for saliva and 100% for the nasal swabs. But Omicron reversed the trend, with 100% agreement between saliva samples and the gold standard, but only 86% for nasal swabs.
COVID testing has used nasal swabs as standard since the discovery of the virus, but that may no longer be appropriate in an Omicron-dominated pandemic landscape, the authors concluded.
“These findings suggest that the pattern of viral shedding during the course of infection is altered for Omicron with higher viral shedding in saliva relative to nasal samples resulting in improved diagnostic performance of saliva swabs,” Hardie and colleagues wrote.
They noted, as have others, that Omicron is distinguished by “more than 50 distinct mutations.” While these increased infectivity, they could also have other effects, including the tissues it may prefer to infect.
The researchers cited a recent unpublished lab study from Hong Kong indicating that Omicron preferentially infects the upper airway. Not only does it suggest Omicron is less lethal, but also that the many mutations confer “altered tissue tropism.”
However, saliva sampling is not as simple as it sounds. At Groote Schuur, patients were instructed to swab the inside of the mouth for a total of at least 30 seconds. They were also told not to eat, drink, smoke, or chew anything for at least 30 minutes beforehand.
While most of the COVID testing kits in the US and elsewhere rely on nasal swabs, any change to saliva sampling would take months – by which time Omicron may have been displaced by another variant.
South Africa’s easing of COVID regulations at the end of 2021 set a new trend in how countries are choosing to manage the pandemic. In an article for The Conversation, Wits University’s Professor Shabir Madhi and colleagues reflect on the boldness – and the risks.
In a significant departure, the government is choosing a new, more pragmatic approach while keeping an eye on severe COVID and threats to health systems. This reflects a willingness to “live with the virus” without causing further damage to the economy and livelihoods, especially in a resource-constrained country.
Prof Madhi and colleagues hope that “the government continues to pursue this approach and doesn’t blindly follow policies that are not feasible in the local context, and ultimately yield nominal benefit.”
This more nuanced approach is a stark contrast to reflexive restrictions in response to rising case rates, suggesting the government has listened to commentary saying that the focus should be on whether health systems are under threat.
A high level of population immunity guides this approach. A sero-survey in Gauteng, just prior to the onset of the Omicron wave indicated that 72% of people had been infected over the course of the first three waves. Sero-positivity was 79% and 93% in COVID unvaccinated and vaccinated people aged over 50: a group that had previously made up a high percentage of hospitalisations and deaths.
The sero-survey data show that immunity against severe COVID in the country has largely evolved through natural infection over the course of the first three waves and prior to the advent of vaccination. This has, however, come at the massive cost of 268 813 deaths based on excess mortality attributable to COVID
Antibody presence is a proxy for underlying T-cell immunity which appears to play an important role in reducing the risk of infection progressing to severe COVID. Current evidence indicates that such T cell immunity, which has multiple targets and even more so when induced by natural infection, is relatively unaffected even by Omicron’s many mutations and likely lasts more than a year. This sort of underpinning T-cell immunity protecting against severe disease should provide breathing space for at least the next 6–12 months, and possibly further.
Despite Omicron’s anti-spike evasion, vaccine and natural infection induced T-cell immunity has been relatively preserved. This could explain the uncoupling of case rate to hospitalisation and death rates. Omicron’s mutations also appear to make it predisposed to infecting the upper rather than the lower airway, reducing the likelihood of progressing to severe disease.
In the meantime, they stress that greater vaccine uptake is ensured, along with boosters for high-risk groups.
Additionally, since low test rates mean only 10% of infections are actually documented in SA , isolation and quarantine are ineffective and a more pragmatic approach is necessary, the authors argued.
As the average person in South Africa could have 20 close contacts per day, contact tracing is of little value, and even symptomatic cases are most infectious in the pre-symptomatic and early symptomatic phase. The fact that three quarters of the SA population were infected over the course of the first three waves demonstrates how ineffective contact tracing and quarantine is. They recommend that certain non-pharmacological interventions should be gradually dropped, especially hand hygiene and superficial thermal screening, while outdoor events should be allowed. Rather, government focus should remain on masking in poorly ventilated spaces and ensuring proper ventilation.
Mandatory vaccinations are still on the radar, since as well as the added risk to others that unvaccinated pose, there is the greater pressure they place on the health systems when they are hospitalised for COVID.
Attention also needs to be given to the management of incidental COVID infections in hospitals. The Department of Health guidance needs to be adapted to manage these patients with the appropriate level of care for the primary reason they were admitted. And patients with severe COVID disease require additional care and expertise to improve their outcomes.
Finally, an evaluation of both vaccination status and underlying immune deficiency needs to become a key element of the workup of hospitalised patients with severe COVID.
The authors stressed the need to minimise hospitalisations and deaths, without damaging livelihoods. SA’s Omicron wave death rate is about a tenth that of Delta, on par with pre-COVID seasonal influenza deaths – 10 000 to 11 000 per annum. TB caused an estimated 58 000 deaths in 2019.
While future variants are unpredictable, there is a trend towards lower rates of hospitalisation and death, especially if vaccine coverage can be increased to 90%, particularly in the over-50 age group. Omicron’s high infection rate will likely also contribute to future protection against COVID.
They note that while there is a risk of new variants, failure to change the pandemic mindset is another risk, as Omicron signals the end of COVID’s epidemic phase.
Past practices have had little effect, the authors concluded, and it is something that the SA government appears to have realised. Despite all the severe lockdowns, SA still suffered a high COVID death rate of 481 per 100 000.
Administering a booster shot of Johnson & Johnson’s COVID vaccine was found to be 85% effective in preventing serious illness in Omicron-dominated areas, preliminary results from a South African trial study show.
The South African Medical Research Council performed the study on health workers from 15 November to 20 December, but has not yet been peer-reviewed. It found the booster was effective in largely protecting staff as Omicron came to dominate the country.
“The increase in CD8+ T-cells generated by the Johnson & Johnson vaccine may be key to explaining the high levels of effectiveness against severe COVID disease and hospitalisation in the Sisonke 2 study, as the Omicron variant has been shown to escape neutralising antibodies,” Johnson & Johnson reported in a statement. That data showed that the booster jab “provides 85 percent effectiveness against hospitalisation in areas where Omicron is dominant/”
“This adds to our growing body of evidence which shows that the effectiveness of the Johnson & Johnson Covid vaccine remains strong and stable over time, including against circulating variants such as Omicron and Delta,” it continued.
Around half a million South African health staff have received Johnson jabs as part of clinical trials. South Africa has recorded more than 3.5 million cases and 94 000 deaths since the start of the pandemic.
An earlier South African study in December found the Pfizer/BioNTech vaccine to be less effective overall against Omicron, but still reduced hospital admissions by up to 70%.
Wastewater monitoringhas shown that COVID infections are falling in Gauteng, indicating that the Omicron wave may have peaked, while the World Health Organization warns that the variant should not be taken lightly despite its mildness.
The findings align with comments by Health Minister Joe Phaahla on Friday that the Omicron-driven wave may be peaking in the province.
Despite Gauteng’s peaking, cases are on the rise in seven of the nine provinces and last week the country saw a new high in cases. Of the infections confirmed on Thursday, Gauteng accounted for 27%, down from 72% of new infections on December 3.
However, the surge of Omicron will likely not be confined to Gauteng. “Early indications are that we might have reached the peak in Gauteng,” Dr Phaahla said in an online media briefing. “But there is a corresponding, rapid increase of cases in the other big provinces.”
He also noted a 70% increase in hospitalisations, though he stressed that this was off of a low base rate. Meanwhile, the WHO has warned that countries should not take the Omicron variant likely in spite of its apparent low severity.
“Countries can – and must – prevent the spread of Omicron with the proven health and social measures. Our focus must continue to be to protect the least protected and those at high risk,” said Dr Poonam Khetrapal Singh, Regional Director of the WHO South-East Asia Region.
Omicron should not be dismissed as mild, she cautioned, adding that even if it does cause less severe disease, the sheer number of cases could once again overwhelm health systems. Hence, health care capacity including ICU beds, oxygen availability, adequate health care staff and surge capacity need to be reviewed and strengthened at all levels.
The overall threat posed by Omicron largely depends on three key questions – its transmissibility; how well the vaccines and prior SARS-CoV-2 infection protect against it, and how virulent the variant is as compared to other variants.
From what we know so far, Omicron appears to spread faster than the Delta variant which has been attributed to the surge in cases across the world in the last several months, Dr Singh said.
She added that emerging data from South Africa suggests increased risk of re-infection with Omicron, and said that there is still limited data on Omicron’s limited severity. Further information is needed to fully understand the clinical picture of those infected with Omicron, and more information is expected in the coming weeks.
Her statements echo those of WHO chief Tedros Adhanom Ghebreyesus, who earlier last week warned that health systems could still be overwhelmed by cases.
A highly anticipated clinical trial in eight sub-Saharan countries is the first to specifically evaluate the efficacy of a COVID vaccine in people living with HIV, including those with poorly controlled infections. It also is the first study to evaluate the efficacy of vaccines – in this case, Moderna mRNA-1273 – against the Omicron variant of SARS-CoV-2.
In addition to examining the efficacy of COVID mRNA vaccines in people living with HIV, the study investigators seek to identify the optimal regimen for this population and how it might vary based on whether an individual has previously had COVID-19 or not.
The trial will be conducted in East and Southern Africa – regions of the world that have been highly impacted by HIV. It is expected to enrol about 14,000 volunteers at 54 clinical research sites in South Africa, Botswana, Zimbabwe, Eswatini, Malawi, Zambia, Uganda and Kenya, where adult HIV prevalence ranges from 4.5% to 27%.
“Sub-Saharan Africa has been hit hard by the COVID pandemic, but access to effective vaccines, especially mRNA technology, has been very limited,” said Dr. Nigel Garrett, co-chair of the study and head of Vaccine and HIV Pathogenesis Research at the Center for the AIDS Program of Research in South Africa (CAPRISA). “The Ubuntu trial will provide safety data to regulators and assess correlates of protection from COVID-19, and it will answer important questions on mRNA vaccine dosage regimens among people living with HIV.”
About 12 600 people living with HIV and about 1400 who are HIV-negative are expected to be enrolled in the study. About 5000 will have previously had COVID, confirmed by an antibody blood test done at initial enrollment. All participants will receive the Moderna vaccine, but dosages and schedules will vary depending on previous SARS-CoV-2 infection. Participants living with HIV will get access to optimal HIV treatment throughout the trial.
“This region faces a huge HIV burden,” said Dr Glenda Gray, Ubuntu study protocol lead adviser and president of the South African Medical Research Council (SAMRC). “Although safe and effective vaccines have been developed for COVID-, HIV and COVID are on a collision course,” she added. “The impact of COVID-19 on people living with HIV is a concern for the continent, particularly in light of the recently-sequenced omicron variant set to drive South Africa’s fourth wave and further infections globally.”
Dr Philip Kotzé, one of the lead study investigators, said the Ubuntu study would not be possible without the crucial participation of rural communities across Southern and East Africa. “These communities have been disproportionately impacted by the twin pandemics of HIV and COVID-19, and they now have an unprecedented opportunity to help advance science and improve our understanding of the immune response to SARS-CoV-2 in the context of HIV.”
Dr Larry Corey, principal investigator of both the HIV Vaccine Trials Network (HVTN) and the COVID-19 Prevention Network (CoVPN), and co-leader of the network’s vaccine testing pipeline, said this study seeks to address the knowledge gap around HIV status and COVID vaccination.
“Vaccination and treatment are critical for those who face the dual threat of HIV and COVID, as they remain at high risk of acquisition and transmission and potentially can be the origin of future variants,” Dr Corey said. “It is imperative that we as scientists and as society double-down on global efforts to find and make available effective vaccines and treatments. This study represents an important step forward in our efforts to reduce the burden of COVID among HIV-infected persons and understand whether current dosage regimens are adequate.”
With the COVID test positivity rate climbing above 30%, President Cyril Ramaphosa is widely expected to address the nation in the coming days. Health Minister Dr Joe Phaahla said on Friday that the National Coronavirus Command Council would be meeting on Tuesday or Wednesday to discuss new restrictions in the face of surging infections.
The main concern is centred around the large number of gatherings that will take place over the festive period: under Level 1 lockdown rules, gatherings of up to 750 individuals are permitted indoors. The Bureau for Economic Research issued a report saying that data so far indicates that there are fewer hospitalisations and less severe disease with the Omicron variant, in line with observations made since the start of the variant’s outbreak.
A partial ban on alcohol sales seems likely, according to a source cited by City Press: “He is considering proposing to the NCCC and cabinet a few adjustments, which include banning the sale of alcohol on weekends and public holidays until mid-January. Don’t be surprised when we have a family meeting before Thursday. He is serious about protecting the country.”
He initially had no plans to address the nation, sources said, but was motivated to change his view in light of the increasing rate of transmission.
Meanwhile, the UK appears set to scrap its controversial red list, which had been widely viewed as unfairly targeting South Africa. The red list amounted to a virtual travel ban, with travellers forced to pay £2285 (R48 400) per person for a ten day stay in often substandard quarantine accommodation. However, it will come too late for many people who have cancelled travel plans.
In a windfall for South Africans, the cost of PCR testing has been revised downward to R500 from R850 as of Sunday following a complaint lodged with the Council for Medical Schemes against private pathology laboratories, alleging the pricing for COVID PCR tests was unfairly inflated. Pricing for rapid antigen tests is said to be next on the list for the Competition Commission.
On Sunday, a technical glitch caused the National Health Laboratory Service to delay release of a large portion of test results. The glitch meant that initially 18 035 cases were released initially, which rose to over 37 000 after the correction.
The cause was put down to IT difficulties with various laboratories.
A report in Nature examines why Omicron was such a surprise, and how the possible evolutionary pathways available to SARS-CoV-2 shape future scenarios of the COVID pandemic.
Currently, Delta and its descendants still dominate worldwide, and they were expected to eventually outcompete the last holdouts. But Omicron has undermined those predictions. “A lot of us were expecting the next weird variant to be a child of Delta, and this is a bit of a wild card,” said Aris Katzourakis, a specialist in viral evolution at the University of Oxford, UK.
The Omicron surge in South Africa suggests that the new variant has a fitness advantage over Delta, said Tom Wenseleers, an evolutionary biologist and biostatistician at the Catholic University of Leuven in Belgium. Omicron has some of the mutations associated with Delta’s high infectivity – but if increased infectivity alone explained its rapid growth, it would mean an R0 (reproduction number) in the 30s, said Wenseleers. “That’s very implausible.”
At present, Omicron appears to have an R0 of 1.36, after its initial surge, based on a continually updated estimate by Louis Rossouw, head of research and analytics at Gen Re. Weneseelers and other researchers instead suspect that Omicron’s rise may be due to its re-infection and vaccine evasion ability.
If Omicron is spreading, in part, because of its ability to evade immunity, it fits in with theoretical predictions about how SARS-CoV-2 is likely to evolve, says Sarah Cobey, an evolutionary biologist at the University of Chicago in Illinois.
As SARS-CoV-2’s infectivity gains start to slow, the virus will maintain its fitness by overcoming immune responses, said Cobey. If mutation halved a vaccine’s transmission blocking ability, this could open up a vast number of hosts. It’s hard to imagine any future infectivity gains providing the same boost.
The evolutionary path towards immune evasion and away from infectivity gains, is common among established respiratory viruses such as influenza, said Adam Kucharski, a mathematical epidemiologist at the London School of Hygiene and Tropical Medicine. “The easiest way for the virus to cause new epidemics is to evade immunity over time. That’s similar to what we see with the seasonal coronaviruses.”
Analysis has shown a wealth of Spike protein mutations that weaken the potency of neutralising antibodies resulting from infection and vaccination. Variants like Beta that have such mutations, have degraded – but not destroyed – vaccine effectiveness particularly against severe disease.
Compared with other variants, Omicron contains many more of these mutations, particularly in the region of spike that recognises host cells. Preliminary analysis from evolutionary biologist Jesse Bloom suggests that these mutations might render some portions of Spike unrecognisable to the antibodies raised by vaccines and previous infection with other strains. But lab experiments and epidemiological studies will be needed to fully appreciate the effects of these mutations.
Evolutionary costs and benefits Evolving to evade immune responses such as antibodies could also carry some evolutionary costs. A Spike mutation that dodges antibodies might reduce the virus’s ability to recognise and bind to host cells. The receptor-binding region of Spike, the main target for neutralising antibodies. is relatively small, explained Jason McLellan, a structural biologist at the University of Texas at Austin. Thus, the region might tolerate only small changes if it retains its main function of attaching itself to host cells’ ACE2 receptors.
Repeat exposures to different Spike versions, through infection with different virus strains, vaccine updates or both, eventually might build up a wall of immunity that SARS-CoV-2 will have difficulty overcoming. Mutations that overcome some individuals’ immunity might not work on the whole population, and T-cell-mediated immunity, another arm of the immune response, seems to be more resilient to changes in the viral genome.
SARS-CoV-2’s evasion of immunity might be slowed by these constraints, but they are unlikely to stop it, said Bloom. Evidence shows that some antibody-dodging mutations do not carry large evolutionary costs, said McLellan. “The virus will always be able to mutate parts of the Spike.”
A virus in transition How SARS-CoV-2 evolves in response to immunity has implications for its transition to an endemic virus. There wouldn’t be a steady baseline level of infections, says Kucharski. “A lot of people have a flat horizontal line in their head, which is not what endemic infections do.” Instead, the virus is likely to cause outbreaks and epidemics of varying size, like influenza and most other common respiratory infections do.
To predict what these outbreaks will look like, scientists are investigating how quickly a population becomes newly susceptible to infection, says Kucharski, and whether that happens mostly through viral evolution, waning immune responses, or the birth of new children without immunity to the virus. “My feeling is that small changes that open up a certain fraction of the previously exposed population to reinfection may be the most likely evolutionary trajectory,” said Rambaut.
The best outlook for SARS-CoV-2, but also the least likely, would be for it to follow measles. Lifetime protection results from infection or vaccination and the virus circulates largely on the basis of new births. “Even a virus like measles, which has essentially no ability to evolve to evade immunity, is still around,” said Bloom.
A more likely, but still relatively hopeful, parallel for SARS-CoV-2 is a pathogen called respiratory syncytial virus (RSV). Most people get infected in their first two years of life. RSV is a leading cause of hospitalisation of infants, but most childhood cases are mild. Waning immunity and viral evolution together allow new strains of RSV to sweep across the planet each year, infecting adults in large numbers, but with mild symptoms thanks to childhood exposure. If SARS-CoV-2 follows this path – aided by vaccines that provide strong protection against severe disease – “it becomes essentially a virus of kids,” Rambaut said.
Influenza offers two other scenarios. The influenza A virus, which drives global seasonal influenza epidemics each year, is characterised by the rapid evolution and spread of new variants able to escape the immunity elicited by past strains. The result is seasonal epidemics, propelled largely by spread in adults, who can still develop severe symptoms. Flu jabs reduce disease severity and slow transmission, but influenza A’s fast evolution means the vaccines aren’t always well matched to circulating strains.
But if SARS-CoV-2 evolves to evade immunity more sluggishly, it might come to resemble influenza B. That virus’s slower rate of change, compared with influenza A, means that its transmission is driven largely by infections in children, who have less immunity than adults.
How quickly SARS-CoV-2 evolves in response to immunity will also determine the need for vaccine updates. The current offerings will probably need to be updated at some point, says Bedford. In a preprint5 published in September, his team found signs that SARS-CoV-2 was evolving much faster than seasonal coronaviruses and even outpacing influenza A, whose major circulating form is called H3N2. Bedford expects SARS-CoV-2 to eventually slow down to a steadier state of change. “Whether it’s H3N2-like, where you need to update the vaccine every year or two, or where you need to update the vaccine every five years, or if it’s something worse, I don’t quite know,” he says.
Although other respiratory viruses, including seasonal coronaviruses such as 229E, offer several potential futures for SARS-CoV-2, the virus may go in a different direction entirely, say Rambaut and others. The sky-high circulation of the Delta variant and the rise of Omicron, aided by inequitable vaccine roll-outs to lower-income countries and minimal control measures in certain large developed countries such as the US, offer fertile ground for SARS-CoV-2 to take additional surprising evolutionary leaps.
For instance, a document prepared by a UK government science advisory group in July raised the possibility that SARS-CoV-2 could become more severe or evade current vaccines by recombining with other coronaviruses. Continued circulation in animal reservoirs, such as mink or white-tailed deer, brings more potential for surprising changes, such as immune escape or heightened severity.
It may be that the future of SARS-CoV-2 is still in human hands. Vaccinating as many people as possible, while the jabs are still highly effective, could stop the virus from unlocking changes that drive a new wave. “There may be multiple directions that the virus can go in,” said Rambaut, “and the virus hasn’t committed.”
Scientists have reported identifying a ‘stealth’ version of Omicron that cannot be distinguished from other variants based on standard PCR tests.
The so-called stealth variant has a number of mutations in common with standard Omicron, but it lacks the key genetic change that makes it stand out in PCR tests. This means probable cases are not flagged by routine PCR tests, even though genomic testing can identify it as the Omicron variant.
This distinctive marker had been one of the fortunate features of the new variant, as Tulio de Oliveira, director of the Centre for Epidemic Response and Innovation in South Africa, had explained: “We can detect [Omicron] very quickly, and this will help us to track and understand the spread.”
It is still too early to know whether the new form of Omicron will spread in the same way as the standard Omicron variant, researchers say. However the ‘stealth’ version is genetically distinct and so may behave differently.
The stealth variant was first spotted among recently submitted COVID virus genomes from South Africa, Australia and Canada, but it may already have spread more widely. So far it has been detected in seven individuals.
As a result of this new variant, researchers have split the B.1.1.529 lineage into standard Omicron (BA.1) and the newer variant (BA.2).
“There are two lineages within Omicron, BA.1 and BA.2, that are quite differentiated genetically,” said Professor Francois Balloux, director of the University College London Genetics Institute. “The two lineages may behave differently.”
Whole genome analysis confirms which variant has caused a COVID infection, but PCR tests can sometimes give an indication. About half of the UK’s PCR machines search for three genes in the virus, but Omicron only tests positive for two. This is because Omicron has a deletion in the “S” or spike gene, similar to Alpha before it. This glitch means PCR tests displaying so-called “S gene target failure” strongly suggest Omicron infection.
Informally, some researchers are calling the new variant “stealth Omicron” because it lacks the deletion that allows PCR tests to spot it.
One major unknown is how the new variant emerged. While it falls under Omicron, it is so genetically distinct that it may qualify as a new “variant of concern” if it spreads rapidly. Having two variants arise in quick succession with shared mutations is “worrying” according to one researcher, and suggests public health surveillance “is missing a big piece of the puzzle”.
While Omicron appears to be extremely transmissible and has been shown to have a greater ability to evade immunity from vaccination and prior infection, there is some evidence the Omicron variant may cause less severe disease.
In Gauteng, NICD hospital surveillance data show that 1904 COVID cases were admitted last week, and 177 COVID patients are currently in ICU with 51 ventilated as of yesterday. Nationwide, 13 147 new cases were detected with a positivity rate of 24.86%. While the fourth wave is still in the early stages, with a higher proportion of younger patients who develop less severe disease, anecdotal evidence points to reduced severity with the Omicron variant.
According to the Financial Times, preliminary data from the Steve Biko and Tshwane District Hospital Complex showed that on December 2 only nine of the 42 patients on the COVID ward, all of whom were unvaccinated, were being treated for the virus and were in need of oxygen. The remainder of the patients were COVID positive but asymptomatic and were being treated for other conditions.
“My colleagues and I have all noticed this high number of patients on room air,” said Dr Fareed Abdullah, an infectious disease doctor at the Steve Biko hospital and a director of the South African Medical Research Council.
“You walked into a COVID ward any time in the past 18 months… you could hear the oxygen whooshing out of the wall sockets, you could hear the ventilators beeping… but now the vast majority of patients are like any other ward.”
US chief medical adviser Dr Anthony Fauci remarked that initial South African data was “a bit encouraging regarding the severity”.
“Thus far, it does not look like there’s a great degree of severity to it,” he said. “But we’ve really got to be careful before we make any determinations.” Existing vaccines could provide “a considerable degree” of protection against Omicron, he added.
A small positive note for South Africa was Dr Fauci saying the administration is reevaluating the travel ban on eight southern African countries as more becomes known about Omicron and its spread.
“That ban was done at a time when we were really in the dark – we had no idea what was going on,” he said.
