Previous COVID infection more protective than vaccination during Delta surge-US study
Previous COVID infection more protective than vaccination during Delta surge-US study

Previous COVID infection more protective than vaccination during Delta surge-US study

La’nya Middleton, 14, is being treated for coronavirus (COVID-19) at the Children’s Hospital of Georgia in Augusta, Georgia, USA, January 14, 2022. REUTERS / Hannah Beier

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Jan 19 (Reuters) – People who had previously been infected with COVID-19 were better protected against the Delta variant than those vaccinated alone, suggesting that natural immunity was a more potent shield than vaccines against this variant, health officials in California and New York reported Wednesday.

However, protection against Delta was highest among individuals who had both been vaccinated and had survived a previous COVID infectionand lowest among those who had never been infected or vaccinated, the study found.

Nevertheless, vaccination remains the safest strategy against COVID-19, according to the report published in the US Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report.

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The results do not apply to the Omicron variant of the virus, which now accounts for 99.5% of COVID-19 cases in the United States.

“The evidence in this report does not change our vaccination recommendations,” Dr. Ben Silk of the CDC and one of the study’s authors for a media briefing.

“We know that vaccination is still the safest way to protect yourself from COVID-19,” he said.

For the studyCalifornia and New York health officials collected data from May to November, which included the period when the Delta variant was dominant.

It showed that people who survived a previous infection had a lower incidence of COVID-19 than people who had been vaccinated alone.

It represented a change from the period when the Alpha variant was dominant, Silk told the briefing.

“Before the Delta variant, COVID-19 vaccination resulted in better protection against a subsequent infection than surviving a previous infection,” he said.

But in the summer and fall of 2021, when Delta became the predominant circulating iteration of the virus in the United States, “surviving a previous infection now provided greater protection against the subsequent infection than vaccination,” he said.

However, gaining immunity through natural infection carries significant risks. According to the study, about 130,781 residents of California and New York had died on November 30, 2021, of COVID-19.

The analysis did not include information on the severity of the initial infection, nor does it take into account the full range of disease caused by previous infection.

An important limitation of the study was that it ended before administration of vaccine booster doses was widespread.

Dr. Erica Pan, state epidemiologist for California’s Department of Public Health, said in an email that the study “clearly shows” that vaccines provide the safest protection against COVID-19, and they offer extra protection to those with previous infections.

“Outside of this study, recent data on the highly contagious Omicron variant show that getting a booster provides significant additional protection against infection, hospitalization and death,” Pan said.

Silk said the CDC is studying the impact of vaccination, boosters and past infection during the Omicron rise and expects to issue additional reports when these data become available.

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Reporting by Julie Steenhuysen in Chicago and Manas Mishra in Bengaluru; Editing Bill Berkrot

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