COVID-19 vaccines are better in terms of protection than so-called natural immunity, according to a new Centers for Disease Control and Prevention (CDC) study.
Researchers with the health agency used data from a CDC-funded network of hospitals and attempted to estimate the odds of contracting COVID-19.
They formed two groups: one with people who had been fully vaccinated with no documentation of previous COVID-19 infection and one with people who had not received a vaccine but had recovered from the disease. Both groups met the criteria if they tested positive for COVID-19, were hospitalized with a COVID-19-like illness between January and September, and were 18 or older.
Researchers said the unvaccinated with natural immunity, or previous infection, were 5.4 times as likely to contract COVID-19, though that figure dropped to 2.5 times among those 18 and 64 and was nearly 20 times among those 65 and older.
The adjusted odds ratio was calculated using various inputs, including age and geographic region.
“We now have additional evidence that reaffirms the importance of COVID-19 vaccines, even if you have had prior infection,” CDC Director Dr. Rochelle Walensky said in a statement.
The results line up with some other studies but differ greatly from still others, including a major real-world study from Israel that found natural immunity gave better protection than Pfizer’s COVID-19 vaccine.
“This variation is possibly related to differences in the outcome of interest and restrictions on the timing of vaccination. The Israeli cohort study assessed any positive SARS-CoV-2 test result, whereas this study examined laboratory-confirmed COVID-19 among hospitalized patients. The Israeli cohort study also only examined vaccinations that had occurred 6 months earlier, so the benefit of more recent vaccination was not examined,” the CDC researchers said.
