South Africa Data Shows Omicron Can Evade COVID Vaccine, Shots Prevent Hospitalization

COVID-19 vaccines appear to offer lower levels of protection against contracting the Omicron variant compared to previous strains, but they largely remain effective in preventing hospitalizations, according to an analysis of data in South Africa.

Since Omicron was first identified last month, the variant has spurred an infection surge in the country and now accounts for more than 90 percent of all new cases, according to Discovery Health chief executive Dr. Ryan Noach.

The analysis, conducted by the South African Medical Research Council and Discovery Health, the country's largest private health insurer, looked at more that 211,000 positive COVID test results. Of those, 41 percent came from adults fully inoculated with the Pfizer vaccine, and about 78,000 of the positive cases were Omicron.

People who received two shots of the Pfizer vaccine had 33 percent protection against becoming infected with the variant, according to data gathered from November 15 to December 7. The protective capabilities were a steep drop from the 80 percent protection against contracting COVID-19 in earlier periods of the pandemic.

The Pfizer vaccine offered better protection against hospitalization during South Africa's Omicron surge, but the 70 percent is still a decrease from the 93 percent protection during the country's virus wave driven by the Delta variant.

Omicron Analysis
COVID-19 vaccines appear to offer lower levels of protection against contracting the Omicron variant compared to previous strains, but they largely remain effective in preventing hospitalizations. Above, Takalane Mulaudzi, 29, grimaces as she gets her COVID-19 vaccination at Soweto's Baragwanath hospital on December 13, 2021. Jerome Delay/AP Photo

While the findings released Tuesday are preliminary and have not been peer-reviewed—the gold standard in scientific research—they line up with other early data about omicron's behavior, including that it seems to be more easily transmitted.

Researchers around the world are rushing to figure out what Omicron will mean for the pandemic. More information came Tuesday from Pfizer, which announced that its experimental pill to treat COVID-19—separate from it its vaccine—appears effective against the new variant.

The company also said full results of its 2,250-person study confirmed the pill's promising early results against the virus: The drug reduced combined hospitalizations and deaths by about 89 percent among high-risk adults when taken shortly after initial virus symptoms. Separate laboratory testing shows the drug retains its potency against the Omicron variant.

In the weeks since omicron was detected, South Africa has experienced rapid spread of the virus—concentrated in its most populous province, Gauteng. The seven-day rolling average of daily new cases in the country rose over the past two weeks from 8.07 new cases per 100,000 people on November 29 to 34.37 new cases per 100,000 people on December 13, according to Johns Hopkins University. The death rate hasn't increased during that same period.

"The Omicron-driven fourth wave has a significantly steeper trajectory of new infections relative to prior waves. 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," Noach said.

Although case numbers are rising, hospitalizations are not increasing at the same rate, leading the scientists to report that the risk of hospitalization from Omicron is lower than Delta or earlier variants. Hospital admissions for adults diagnosed with COVID-19 are 29 percent lower compared to the wave that South Africa experienced in mid-2020, after adjusting for vaccination status, according to the analysis.

The study shows that significant protection against hospital admission even among older age groups, with 67 percent in people aged 60 to 69 and 60 percent for people aged 70 to 79.

The South African analysis supports an earlier assessment by U.K. authorities.

The U.K. Health Security Agency said Friday that new data from the U.K. confirm that Omicron is more easily transmissible than other variants. Other studies suggest that both the AstraZeneca and Pfizer vaccines are less effective in preventing symptomatic infections in people exposed to Omicron, though preliminary data show that effectiveness appears to rise to between 70 percent and 75 percent after a third booster dose.

The study also found that omicron poses a higher risk of reinfection. For individuals who have previously had COVID-19, the risk of reinfection with omicron is significantly higher than that of earlier variants.

The Associated Press contributed to this report.

COVID-19 Sequencing
Since Omicron was first identified last month in South Africa, the variant has spurred an infection surge in the country and now accounts for more than 90 percent of all new cases. Above, Puseletso Lesofi prepares to sequence COVID-19 omicron samples at the Ndlovu Research Center in Elandsdoorn, South Africa, on December 8, 2021. Jerome Delay/AP Photo