'Spreading at a rate we have not seen' - Omicron more resistant to COVID-19 vaccines

  • The new study from South Africa's largest private health insurer shows that two shots of the Pfizer-BioNTech vaccine is just 33% protective against omicron.
  • Full vaccination against COVID-19 continues to provide 70% protection against severe disease, according to the Discovery Health study.
  • Omicron also appears to be able to reinfect people who had an earlier disease variant, with those infected longer ago at higher risk of reinfection.

The new omicron variant of the coronavirus is substantially more contagious and reduces the effectiveness of COVID-19 vaccines, a study from South Africa released Tuesday found.

Even though the variant so far seems to produce mostly mild disease, world health leaders warned it could bring a wave of illness that crushes health systems

"Omicron is spreading at a rate we have not seen with any previous variant," said Dr. Tedros Adhanom Ghebreyesus, director-general of the World Health Organization.

"We underestimate this virus at our peril," he said in a news conference Tuesday from Geneva. "Even if omicron does cause less severe disease, the sheer number of cases could once again overwhelm unprepared health systems."

Early data from South Africa appears to show that people who are fully vaccinated are still largely protected against severe disease, according to early data released Tuesday by Discovery Health, South Africa's largest private health insurer.

The omicron variant, which was first identified in southern Africa, appears poised to take over the world, as delta did before it. Omicron accounts for 90% of COVID-19 cases in South Africa and is a growing problem in Europe

It has now been found in 77 countries, Ghebreyesus said. It has been seen in at least 30 U.S. states, though the delta variant still dominates the American outbreak.

Formally identified the day before Thanksgiving, information on omicron's characteristics – including how contagious and dangerous it may be – are just emerging.

The new study from Discovery Health shows that two shots of the Pfizer-BioNTech vaccine, which provided more than 90% protection against the original virus, is only 33% protective against omicron infection.

Full vaccination continues to provide 70% protection against severe disease, which seemed to hold up across high-risk groups, though it declined somewhat in people over 60 and even more in those over 70. 

"This is the first time we've had any data on that," said Dr. Eric Topol, vice president for research at Scripps Research in La Jolla, California, and a national expert on the use of data in medical research.

"Seventy percent is definitely a dropdown. It isn't great," he said. "It was 95% effective severe disease when it was delta variant and then about 85% after six months of waning," he said. 

Whether those numbers will continue to hold as more patients with omicron are studied isn't yet clear, he said. "This is all still so new."

People queue to get a coronavirus booster jab at St Thomas' Hospital, backdropped by the scaffolded Elizabeth Tower, known as Big Ben, and the Houses of Parliament, in London, Monday, Dec. 13, 2021. Long lines formed at vaccination centers in Britain as people heeded the government's call for all adults to get booster shots to protect against the omicron variant of the coronavirus, which the prime minister said Monday has caused at least one death. (AP Photo/Matt Dunham)

Other research from Pfizer-BioNTech suggests that a third, booster dose can restore the original levels of protection at least for some period of time.

“The Omicron-driven fourth (wave) has a significantly steeper trajectory of new infections relative to prior waves," Dr, Ryan Noach, CEO of Discovery Health, said in a statement. "National data show an exponential increase in both new infections and test positivity rates during the first three weeks of this wave, indicating a highly transmissible variant with rapid community spread of infection.”

Mild but dangerous

WHO officials chided nations that are focusing on offering boosters to their citizens while ignoring the lack of vaccines globally.

"The priority in every country and globally must be to protect the least protected, not the most protected," Tedros said. 

Vaccine for poor countries has dealt with many setbacks over the past year, brought on by export restrictions, vaccine hoarding and regulatory delays, COVAX, the global vaccine alliance, said in a statement Tuesday. However, supply has increased since September.

Even if mild, omicron could easily overwhelm health systems even in highly developed nations said Dr. Michael Ryan, Executive Director of the WHO Health Emergencies Programme.

"If you have a huge wave of cases, you will see a lot of severity and you will see hospital systems coming under pressure," he said.

He warned already stressed heath systems may fail, and urged they prepare now.

"Make sure you have the health workers in place, make sure you have the clinical trials in place. Make sure you've got oxygen supplies in place. Make sure that you're vaccinating the unvaccinated," Ryan said. "Make sure you're taking every opportunity individually and at the community level to stop transmission where you can."

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Omicron appears able to reinfect people who caught an earlier variant of the virus, and those infected longer ago are at higher risk of reinfection.

People infected in South Africa's first wave early last year, have a 73% chance of reinfection, while those infected with the beta variant have a 60% chance of reinfection and those infected in its most recent delta wave face a 40% risk of reinfection with omicron, the new study showed.

That fits with findings from a preliminary briefing released by the United Kingdom on Friday showing an approximately three- to eight-fold increased risk of reinfection with the omicron variant, Topol said.

There has been some hope that omicron would cause fewer cases of severe disease than its predecessors, but that remains unclear.

The rate of hospital and intensive care unit admissions is lower than with other variants – 29% lower than with the first wave of infections early last year, according to the study. But that may be because so many South Africans recently recovered from infections with delta, Noach said. 

Coronavirus testing is available in Times Square in New York City. After the discovery of the omicron variant, health officials urge people to get vaccine boosters.

Children continue to show a relatively low rate of infection with omicron, as they have with earlier variants, the study showed.

Children infected with omicron have so far had a 20% higher risk of hospital admission for complications than they did with earlier variants, according to Shirley Collie, chief health analytics actuary at Discovery Health.

“This is early data and requires careful follow up," Collie said in a company press release. But the finding lines up with an earlier warning from South Africa’s National Institute for Communicable Diseases of an increase in hospital admissions for children under 5.

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Anecdotal reports from South African hospitals suggest that most young children hospitalized with COVID-19 tested positive on routine screening, after going to the hospital for an unrelated reason. 

"It's a peculiarity that hasn't been explained," Topol said of the high rate of hospital admissions for children. "It hasn't yet been seen in the United Kingdom, Denmark, Norway and other places hard hit by omicron."

Collie said, “Children were 51% less likely to test positive for COVID19 relative to adults in the Omicron period, and overall, the risk of children being admitted to hospital for COVID19 complications remains low.”

The world shouldn’t focus only on the early data coming out of South Africa and the United Kingdom showing omicron might be milder, because when omicron gets to different populations it might behave differently, said Dr. Abdirahman Mahamud, WHO COVID-19 incident commander.

Even if omicron does prove to be milder, delta remains a threat.

“We are caught between two elephants, the delta and the omicron,” he said. “These are massive, angry elephants.”

Contact Elizabeth Weise at eweise@usatoday.com

Contact Karen Weintraub at kweintraub@usatoday.com.

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