The Delta variant of COVID-19 was an unwelcome surprise last year as it blitzed across the United States, making for a difficult second half of 2021. But with Delta falling from the headlines, it is worth examining who fared best against Delta and what it means for the fight against Omicron.

On Wednesday, the Centers for Disease Control and Prevention (CDC) released a new study that aimed to provide some answers to this question. What it found was that Americans who were fully vaccinated suffered the least during the wave of Delta infections last year. There is a catch to this too; vaccinated Americans who were previously infected by COVID-19 outperformed every other group in resisting Delta in the end.

The study looked at four categories of people in New York and California: individuals who were unvaccinated with and without a prior infection and vaccinated people with and without a prior infection. What it learned was that those previously infected with COVID-19, whether vaccinated or unvaccinated, demonstrated higher levels of protection than those who were not.

Certain caveats also apply to the CDC study. For instance, the study was conducted primarily before larger numbers of Americans received either their first COVID-19 doses or their booster shots. Today, the CDC estimates that 79.9% of Americans received at least one dose of a COVID-19 vaccine, but the study was limited to cases between March and May 2021 before vaccinations became more widely available.

There is a chance that these results can be seized on by advocates for developing natural immunity over getting vaccinated. Throughout last year, the idea has been pushed by a mixture of voices that ranges from celebrities to vaccine skeptics, but medical professionals consider the idea of encouraging the idea dangerous.

The authors did not elaborate on why prior infection specifically protected against Delta, but the study’s authors maintained that primary and booster vaccinations remained the safest way and the best defense against serious infections.

“A Covid vaccination helps protect by creating an antibody response without the person having to experience severe illness and death," said Benjamin Silk, a CDC scientist and one of the study's authors, during a call with reporters. “Vaccination provides safer protection.”

In terms of what this study may mean for the fight against Omicron, the CDC said that the two strains could not be compared and that it would soon be releasing more studies on Omicron specifically.

“[The study] offers a framework for analyzing surveillance data that we know will help evaluate infection in vaccinated persons and reinfection as new variants like Omicron continue to emerge,” said Silk.

RELATED STORIES
CDC