A Jan. 19 report from the Centers for Disease Control and Prevention (CDC) showed natural immunity against COVID was at least three times as effective as vaccination alone at preventing people from becoming infected with the Delta variant.
Overall, the study showed natural immunity outperformed vaccine immunity when it came to preventing infection and hospitalization from Delta.
The results contradicted a previous CDC study, published in August 2021, which concluded vaccination was better than natural immunity. The CDC issued a media statement about the August study, which was widely covered by the mainstream press.
When a much larger Israeli study was published two weeks later, finding the opposite, the CDC did not offer any comment or analysis on the new data.
“The CDC is now finally revising its position five months later,” said Dr. Madhava Setty, senior science editor for The Defender. “This is a major problem with the CDC and its data. They have been opaque and late to the game from the beginning.”
Are vaccines interfering with natural immunity?
The latest CDC study examined four categories of people in California and New York between May and November 2021: unvaccinated and vaccinated who survived a previous COVID infection, and unvaccinated and vaccinated who had never been infected.
While the highest case rates were among those who had neither previous exposure nor vaccination, the outcomes with Delta for those who were unvaccinated but previously exposed were substantially better than for those whose immunity came from vaccination alone.
Unvaccinated, recovered individuals had infection rates 14.7 (N.Y.) to 29 (Calif.) times lower than those who had no immunity, while the vaccinated who had no prior COVID exposure had rates 4.5 (N.Y.) to 6.2 (Calif.) lower than those without any immunity.
The results were similar for hospitalization: Those with natural immunity were 2- 6 times less likely to be hospitalized than those with vaccinated immunity alone.
Additionally, the week-by-week hospitalization risk data often showed natural immunity registering lower risk rates than even hybrid immunity (vaccination plus prior recovery from COVID).
During the last three months of the study (Sept. 4 to Nov. 13), the hazard rate of hospitalization for those with natural immunity was typically 20 or more points lower than the hazard rates for those with hybrid immunity.
The report did not offer cumulative, comparative data on hospitalization rates.
“This is potentially a concerning finding in that it suggests the vaccine could be interfering with natural immunity,” Setty said.
Summarizing the data, the CDC made reference to the now well-documented decline of vaccinated immunity during Delta:
“Case rates were initially lowest among vaccinated persons without a previous COVID-19 diagnosis; however, after the emergence of the Delta variant and over the course of time, incidence increased sharply in this group [those with vaccinated immunity], but only slightly among both vaccinated and unvaccinated persons with previously diagnosed COVID-19.”
The CDC cautioned the data in question measured results only against the Delta variant and Omicron may present new challenges that could alter the comparison of natural immunity to vaccination.
The authors also emphasized that data clearly indicated the unvaccinated without prior exposure had the highest infection and hospitalization rates.
Why aren’t we doing ‘gold standard’ testing on natural immunity?
Analyzing the data on his YouTube channel, Dr. Vinay Prasad, associate professor of epidemiology and biostatistics at the University of California — San Francisco said:
‘This finally confirms something that a lot of people have known to be true and is supported by Israeli data — but there’s been a lot of fragmentary data on this question — which is: If you have had COVID-19 and recovered, your probability of catching the virus again and getting so sick you require hospitalization is very, very, very low.
“Biden administration officials and some public health experts, including CDC Director Dr. Rochelle Walensky, have repeatedly dismissed the value of natural immunity against COVID-19.”
In fact, the more recent study of people in New York and California is only the latest to indicate that recovery from prior infection can at least rival, if not surpass, the immunity provided by vaccination alone.
In December, a South African study found Omicron provided robust immunity against both reinfection and exposure to the Delta strain, and last fall a major study found natural COVID immunity provided 6-13 times better defense against Delta than the Pfizer vaccine.
Summing up his analysis, Prasad praised the CDC study for looking at “clinically relevant endpoints,” but added:
“What would be even better, would be to run randomized control trials in every single one of these groups randomized to different doses and different strategies of vaccination … to have enough power in these randomized control trials to see interaction by age or comorbidity.
“That would be the gold standard, and, in fact, companies have a lot of money and the [U.S. Food and Drug Administration] could have compelled them to do that, but instead we have a very low regulatory standard which is something I have quite a problem with.”
