Patients hospitalized with COVID-like symptoms were five times more likely to test positive for Sars-Cov-2, if they were unvaccinated and had a prior history of having COVID-19, compared to those who received the Moderna or Pfizer vaccine and had no history of coronavirus infection, according to a report last week by the CDC.
CDC researchers looked at data collected from more than 7,000 hospitalized adults, ages 18 and over, who had symptoms associated with COVID-19, in 187 hospitals throughout nine states. The researchers were comparing the early protection against COVID-19 developed from having a previous SARS-CoV-2 infection with that developed from receiving mRNA COVID-19 vaccines. The health organization used VISION Network who collected the data during the period from January–September 2021. The CDC then analyzed data to compare the odds of testing positive for SARS-CoV-2 between the unvaccinated group who had previous COVID infections at least 90-179 days prior to hospitalization with those who were fully vaccinated 90-179 days prior to the recent hospitalization and had no history of having the illness.
The researchers found, of the unvaccinated adults who had coronavirus at least 3 months prior to the new hospital admission, 8.7 percent tested positive for coronavirus again. Meanwhile, a lesser percent of those who were fully vaccinated with the mRNA vaccine (Pfizer or Moderna), and had no prior infection, 5.1 percent, tested positive for COVID-19, according to the Morbidity and Mortality Weekly Report on the CDC website.
The report stated that the “vaccine-induced immunity was more protective than infection-induced immunity against laboratory-confirmed COVID-19.”
The study also noted that secondary analyses that did not adjust for time regarding previous infection or vaccination as well as before and during the predominance of the delta variant produced similar results. The findings coincide with previous studies that vaccine immunity is stronger than infection-induced immunity regarding the occurrence of COVID reinfection.
“These findings are consistent with evidence that neutralizing antibody titers after receipt of 2 doses of mRNA COVID-19 vaccine are high”, the authors stated in the CDC report.
The findings do differ from a non -peer reviewed retrospective study in Israel, which did not find higher protection in vaccinated adults compared to those with previous COVID infections during the Delta variant predominance.
The CDC authors noted the Israeli study assessed any positive SARS-CoV-2 test, where this particular study looked at laboratory-confirmed COVID-19 molecular tests. The authors also said the Israeli report only examined vaccinations that were received 6 months prior, so the benefits of recent vaccination were not taken into account.
“This report focused on the early protection from infection-induced and vaccine-induced immunity, though it is possible that estimates could be affected by time.” The report addressed the importance of continued studies to gain an understanding of vaccine-induced and infection–induced immunity against COVID 19.
The authors of the CDC report concluded, “All eligible persons should be vaccinated against COVID-19 as soon as possible, including unvaccinated persons previously infected with SARS-CoV-2.”
Dr. Aaron Glatt, a spokesperson for the American Infectious Diseases Society, was not associated with the study but told Fox News there remains much we do not know about COVID-19. The epidemiologist also told Fox News, “The body of evidence is growing, including this paper, to support the idea that vaccination provides better overall immunity than COVID infection natural immunity. We look forward to additional evidence that can provide us with even more specific recommendations, to know when is the optimal time to vaccinate post-COVID infection.”