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The COVID-19 study: Do vaccinations provide greater protection than infection-induced immunity?

a doctor attending to a covid 19 patient
  • Having had an infection with SARS-CoV-2 or receiving the COVID-19 vaccine may confer immunity and protection against future sickness.
  • The amount of immunity supplied by a past infection was compared to the level of protection offered by the COVID-19 vaccine in a recent trial, according to the researchers.
  • According to the findings, COVID-19 mRNA vaccinations are about five times more efficient at avoiding hospitalization than a prior infection at preventing hospitalization.

Regarding SARS-CoV-2 immunity, there are several doubts and contradicting facts that continue to circulate. When it comes to COVID-19, one of the most often asked questions is, “Do I still need to be vaccinated if I have had the virus?”

A recent research conducted by the Centers for Disease Control and Prevention (CDC) aimed to resolve the debate over whether vaccine-induced immunity is superior than infection-induced immunity.

Researchers from the Centers for Disease Control and Prevention’s VISION network collected data from 187 hospitals in nine states. New York, Minnesota, Wisconsin, Utah, California, Oregon, Washington, Indiana, and Colorado were among the states that have done so.

The investigational strategy

Between January and September of 2021, almost 200,000 people were admitted to these hospitals with conditions that were similar to COVID-19.

The research included participants who were 18 years or older and who had previously been tested for SARS-CoV-2 infection at least 2 weeks before their admission to the hospital, as well as again around the time of their admission to the hospital. All subjects had either been completely vaccinated against SARS-CoV-2 3–6 months previously or had a previous SARS-CoV-2 infection 3–6 months before taking part in the study.

Following an investigation of the data, it was discovered that 7,348 persons, or little more than 3% of the participants, matched the study’s eligibility requirements.

1,020 people had previously contracted the virus and were unvaccinated, whereas 6,328 people were fully vaccinated persons who had not previously caught the infection, according to the data.

By using a COVID-19 polymerase chain reaction (PCR) test, the researchers were able to identify individuals among these groups who had been diagnosed with SARS-CoV-2 infection in a laboratory setting. This instrument, which is also known as a molecular test, is used to identify the genetic material of a virus in the human body.

What the team discovered

A positive COVID-19 PCR test resulted in 324 (or 5.1 percent) of the 6,328 persons who had received their entire vaccination. 89 (or 8.7 percent) of the 1,020 people who were unvaccinated and who had previously contracted the virus had a positive COVID-19 PCR test, according to the findings.

“These findings suggest that among hospitalized adults with COVID-19-like illness who had a previous infection or vaccination that occurred 90–179 days earlier, vaccine-induced immunity was more protective against laboratory-confirmed COVID-19 than infection-induced immunity,” the study’s authors write.

While speaking with Medical News Today about the research, Dr. William Schaffner, professor of medicine and director of the Division of Infectious Diseases at Vanderbilt University School of Medicine in Nashville, TN, shared his thoughts on the findings.

“For a long time, we’ve known that people [who have the infection], if they are subsequently vaccinated, will have much higher levels of antibodies than people who have the infection] but are not vaccinated,” he said. Natural infection in combination with vaccination is preferable to natural infection alone. “

The authors of the study make reference to a previous Israeli study that produced contradicting findings. Natural immunity provides “longer-lasting and greater protection against infection, symptomatic illness, and hospitalization caused by the Delta version of SARS-CoV-2 [than] the BNT162b2 two-dose vaccine-induced immunity,” according to the findings of the Israeli research.

They believe that this variance is due to changes in the methodologies used in the two trials, as well as constraints on when immunizations may be administered.

Moreover, they point out that the Israeli research “only investigated vaccinations that had happened 6 months earlier,” while the latest study included everyone who had gotten their vaccine between 3 and 6 months prior to participating.

The need for more research

The researchers at the Centers for Disease Control and Prevention (CDC) study point up significant limitations.

For example, they explain that “if SARS-CoV-2 testing happened outside of network partners’ medical facilities or if vaccinated [people] are less likely to seek testing, some positive SARS-CoV-2 test results may have been overlooked, and so some [individuals] categorized as vaccinated and previously [free from infection] may also have [had the virus].”

Furthermore, the research only looked at COVID-19 mRNA vaccines. As a consequence, consumers should be cautious about extrapolating the findings to non-mRNA vaccinations, such as the Johnson & Johnson vaccine.

In an interview with MNT, Elitza Theel, Ph.D., the head of the Infectious Diseases Serology Laboratory at the Mayo Clinic in Rochester, Michigan, discussed the study’s shortcomings and how it may be improved.

“There was a notably higher rate of index tests for COVID-19 performed during July–August among previously vaccinated individuals versus individuals [who previously had the infection] who had higher testing rates in March–April. The reason for this was not discussed in the study,” said Theel.

According to the authors, future research should be focused on understanding infection-induced and vaccine-induced immunity in order to better treat patients. “Although the [analysis] concentrated on early protection against infection-induced and vaccine-induced immunity, it is likely that estimates might be influenced by the passage of time,” the researchers write.

According to Theel, when questioned about potential future study topics, “One subject that I continue to be asked about [is] whether a single vaccination shot should be administered to [those who have already had the virus] rather than two.”

Individuals who have already had the virus should be vaccinated, according to the Centers for Disease Control and Prevention, although there is no explicit debate on the topic of one vs two mRNA vaccine doses. Considering the high level of vaccination hesitancy we continue to see, particularly among [those who have already been infected with the virus], I believe it would be helpful to evaluate this further in the future.”

“All eligible individuals should be vaccinated against COVID-19 as soon as feasible, including unvaccinated [those who have previously had] SARS-CoV-2,” the research concluded.

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