There is a lot of conflicting information and uncertainties about SARS-CoV-2 immunity. A recent study from the CDC has researched whether vaccine-induced immunity or infection-induced immunity is better. Data from 187 hospitals across nine states were gathered by the researchers from CDC’s VISION network. The nine states include Colorado, Indiana, Washington, Oregon, California, Utah, Wisconsin, Minnesota, and New York.
Between January and September 2021, there were over 200,000 admissions to these hospitals for Covid like silliness. The study recruited people who were 18 years and older. These people have been tested for the infection previously, at least two weeks before they get admitted to the hospital and again around the time of admission. All the people who took part had either had a previous Covid infection 3-6 months prior or been fully vaccinated 3-6 months earlier.
An analysis of the data showed that 7,348 people met these study criteria, which is a little over 3% of the participants. 1020, among these people, were unvaccinated and previously had the infection. While 6328 people had not had the infection earlier and were fully vaccinated. The researchers then looked for people within these groups who had lab-confirmed Covid infection.
Three hundred twenty-four people among the 6328 people who were fully vaccinated had a positive Covid PCR test. Eighty-nine people among 1020 who had previously had the infection and were unvaccinated had positive Covid PCR test. According to the researchers, these findings indicate that among hospitalized adults with Covid like silliness whose previous vaccination or infection occurred 90–179 days earlier, the induced immunity rather than infection-induced immunity was more effective.
According to Dr. William Schaffner, for a long time, it has been known that people, if they are subsequently vaccinated, will have much higher levels of antibodies than people who have the infections but are not vaccinated. Natural infection and vaccination are better than natural infection. He is a professor of medicine in the Division of infectious diseases at Vanderbilt University School of Medicine in Nashville, TN.
The study researchers referred to the Israeli study, which had different results. It found that natural immunity confers longer-lasting and more robust protection against infection. According to the researchers, this difference is because of differences in the methods of the two studies and restrictions on the timing of vaccinations.
The researchers of the study note several limitations. If the testing occurred outside of network partners’ vaccinate people or medical facilities are less likely to seek testing. There is a possibility that some positive test results might have been missed, and thus some people classified as vaccinated and previously might also have the infection. The study assessed only mRNA vaccines, so people should not generalize the results to non-mRNA vaccines.
According to health experts, there was a notably higher rate of index tests for Covid among previously vaccinated individuals during July-August versus individuals who had higher testing rates in March–April. This was not discussed in the study.
The researchers of this study said understanding infection-induced and vaccine-induced immunity should be the focus of future studies. The study focused on the early protection from vaccine-induced and infection-induced immunity, though it is possible that estimates could be affected by time. The researchers also stressed that all eligible persons should be vaccinated as soon as possible for Covid, including unvaccinated people.