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Real-world data suggest 2 doses of Pfizer vaccine 70% effective at preventing hospitalization with Omicron variant

U.S. hits 800,000 COVID deaths
U.S. hits 800,000 COVID deaths 02:26

South African researchers released encouraging data on Tuesday based on real-world COVID-19 infections in the country during the current, fourth wave of coronavirus infections, driven almost entirely by the new Omicron variant. The preliminary analysis of data gathered by the insurer Discovery, which has not yet been peer-reviewed, shows the standard two-dose regimen of Pfizer-BioNTech's COVID-19 vaccine has been about 70% effective at preventing hospitalization over the last three weeks, as Omicron has swept across the country.

As both vaccinologists and the pharmaceutical companies that make the vaccines have said, the Omicron variant does appear to have a significant ability to evade the vaccines to cause infection. The data released on Tuesday suggests two shots of the Pfizer jab are only about 33% effective at preventing infection.

The findings mirror other preliminary research presented over the last week or so by Pfizer, and scientists in South Africa who have been testing the vaccines against the new variant.

Pfizer said last week that its own lab work showed a third dose, or booster, of its vaccine was highly effective at preventing symptomatic COVID-19 infection with Omicron — about as potent as just two shots had been with the previous, Delta variant.

Dr. David Agus on what the U.S. can learn from the Omicron "tidal wave" headed for the U.K. 02:15

But while the U.S. and other wealthy nations race ahead to administer booster shots, many developing regions are still struggling to get people their first two jabs. Less than 10% of the overall population of Africa is fully vaccinated to date.

In South Africa, only around 30% have been fully vaccinated, but the real-world evidence emerging from the country where Omicron was first detected and has been prevalent for weeks, particularly regarding serious illness, is encouraging.

Fewer people in hospitals

Data show the hospitalization rate for adults during the current wave of COVID infections has been about 29% lower than during the previous Delta wave. Health experts in South Africa have told CBS News that hospitals are a lot less full now than they were when the Delta variant tore through the population.

But Glenda Gray, head of the South African Medical Research Council and one of the leaders of the preliminary study results announced on Tuesday, echoed other experts in the country who've told CBS News that the lower hospitalization rates now are likely thanks in large part to the huge proportion of people who carry some immunity to COVID-19 from previous infection.

She said that in some parts of South Africa, up to 80% of the local population has had COVID-19.

It remains unclear how much previous infection may help to prevent an infection or severe illness with Omicron, but any natural immunity has come at a high price: Nearly 90,000 lives have been lost to the disease in South Africa according to official tallies, but many experts say the real toll is probably closer to 270,000. That may sound low as the U.S. passes the grim milestone of 800,000 coronavirus deaths, but South Africa's population is less than a quarter the size of America's.

South African research finds Omicron variant more contagious but less likely to cause serious illness 03:07

Given the comparatively low vaccination rate in the country, and the uncertainty over immunity from previous infections, Gray cautioned against any assumptions that other countries would see the same or similar results as in South Africa, and she stressed that the new variant is incredibly contagious.

Gray said the single-shot Johnson & Johnson vaccine also appeared to provide good protection against serious illness.

"Although we have had a lot of breakthrough infections, there has been very little hospital admission in comparison to the Delta period," she said at a news conference, according to the Reuters news agency. "As of today, we have had no one who has died from Omicron from the J&J study, so that's the good news, it shows again that the vaccine is effective against severe disease and death."

CBS News correspondent Debora Patta contributed to this report.

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