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2 charts show Covid-19 booster shots' superior protection compared to double vaccination

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A kidney-transplant patient receives a COVID-19 booster shot at Hartford Hospital in Connecticut on August 24, 2021.
  • Boosted people had the best protection against severe disease in Los Angeles this winter, new CDC charts show.
  • Unvaccinated people had 83 times the hospitalisation rate of boosted people when Delta was spreading. 
  • Once the Omicron variant took over, unvaccinated people had 23 times the hospitalisation rate.
  • For more stories visit www.BusinessInsider.co.za

New data from the Centers for Disease Control and Prevention underscores the divide in protection between Covid-19 booster shots and two vaccine doses.

In a study published Tuesday, the CDC found that people who received Covid-19 booster shots following a single dose of Johnson & Johnson's vaccine or two doses of Pfizer or Moderna had greater protection against infection and hospitalisation this winter.

The study looked at adults in Los Angeles County, California, who got Covid-19 from November 2021 to January 2022.

In early December, when the Delta variant was still dominant in LA, unvaccinated people had four times the rate of infection and 13 times the rate of hospitalization as fully vaccinated people without boosters. Compared to boosted people, however, unvaccinated people had 12 times the rate of infection and 83 times the rate of hospitalization.

The pattern held in early January, when Omicron represented the overwhelming majority of Covid-19 cases. At that time, unvaccinated people had double the rate of infection and five times the rate of hospitalisation as fully vaccinated without boosters, but nearly four times the rate of infection and 23 times the rate of hospitalisation as fully vaccinated people with boosters.

No matter which variant was spreading, people who were up-to-date on their shots were heavily guarded against severe disease, as the chart below shows.

CDC

But booster rates in the US remain considerably low compared to many European countries. While nearly 64% of the US is fully vaccinated as of Monday, just 52% of Americans who are eligible for boosters have received one, according to CDC data.

"Biden is right when he says we're facing a pandemic of the unvaccinated — but it's also now becoming a pandemic of the unboosted," Peter Hotez, professor of virology at Baylor College of Medicine, told The Financial Times on Monday. 

Low booster rates are "very high on the list" of reasons Omicron hospitalizations remain so high in the US, Eric Topol, director of the Scripps Research and Translational Institute, added.

Nearly 130,000 people are currently hospitalised with Covid-19 in the US — more hospitalizations than the country recorded during any of the previous waves.

Boosted people had fewer Omicron infections and hospitalisations

Omicron increased the odds of severe disease among all adults in the CDC study, but hospitalisations only ticked up slightly among vaccinated people in LA in December.

By contrast, rates of severe disease skyrocketed among unvaccinated people once Omicron took over, as shown below.

CDC

As of January 8, more than 188 out of 100,000 unvaccinated people in LA were hospitalized with Covid-19, compared with 35 out of 100,000 vaccinated people without boosters and eight out of 100,000 vaccinated people with boosters. A January CDC study found that boosters reduced the risk of hospitalization from Omicron by around 90%.

Boosters also seemed to lower the risk of infection during LA's early Omicron wave.

More than 67 out of 1,000 unvaccinated people in LA were infected with the coronavirus as of January 8, compared with 34 out of 1,000 vaccinated people without boosters and 19 out of 1,000 vaccinated peopled with boosters.

Previous CDC studies have similarly shown that boosters protect against Omicron infections and symptoms. 

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