Prior COVID infection more protective than vaccination during Delta surge -U.S. study
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Protection against Delta was highest, however, among people who were both vaccinated and had survived a previous COVID infection, and 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 U.S. Centers for Disease Control and Prevention CDC Morbidity and Mortality Weekly Report.
The results do not apply to the Omicron variant of the
virus, which now accounts for 99.5% of COVID-19 cases in
"The evidence in this report does not change our vaccination
recommendations," Dr.
"We know that vaccination is still the safest way to protect yourself against COVID-19," he said.
For the study https://www.cdc.gov/mmwr/volumes/71/wr/mm7104e1.htm?s_cid=mm7104e1_e&ACSTrackingID=USCDC_921-DM73434&ACSTrackingLabel=MMWR%20Early%20Release%20-%20Vol.%2071%2C%20January%2019%2C%202022&deliveryName=USCDC_921-DM73434,
health officials in
It showed that people who survived a previous infection had lower rates of COVID-19 than people who were vaccinated alone.
That 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.
In the summer and fall of 2021, however, when Delta became
the predominant circulating iteration of the virus in
But acquiring immunity through natural infection carries
significant risks. According to the study, by
The analysis did not include information on the severity of initial infection, nor does it account for the full range of illness caused by prior infection.
One important limitation to the study was that it ended before administration of vaccine booster doses was widespread.
Dr.
"Outside of this study, recent data on the highly contagious Omicron variant shows 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 prior infection during the Omicron surge and expects to issue further reports when that data becomes available.
(Reporting by