COVID vaccines protect you better than previous infection, another study confirms

A new study of more than 7,000 patients hospitalized with coronavirus-like symptoms found that unvaccinated people who recently had COVID-19 were five times more likely to test positive for COVID-19 than those who were fully vaccinated without a prior infection.

The Centers for Disease Control and Prevention research suggests vaccination — not previous infection — is the best protection against COVID-19, offering “higher, more robust and more consistent level of immunity” for at least six months.

Adults included in the study were hospitalized with COVID-19-like illness between January and September across 187 hospitals in nine states. Patients’ previous infection or vaccination with either the Pfizer or Moderna shots occurred anywhere between three to six months before the study began.

The purpose of the study was to find the odds of testing positive for COVID-19 among those hospitalized with coronavirus-like symptoms depending on infection history or vaccination status.

The findings, released Oct. 29 in the CDC’s “Morbidity and Mortality Weekly Report” add to a growing body of evidence that suggests vaccine-induced immunity is better than that of previous infection.

“We now have additional evidence that reaffirms the importance of COVID-19 vaccines, even if you have had prior infection. This study adds more to the body of knowledge demonstrating the protection of vaccines against severe disease from COVID-19,” CDC Director Dr. Rochelle Walensky said in a statement. “The best way to stop COVID-19, including the emergence of variants, is with widespread COVID-19 vaccination and with disease prevention actions such as mask wearing, washing hands often, physical distancing, and staying home when sick.”

There are certain illnesses in which infection can offer more protection than a vaccine.

For example, coming down with measles or mumps is said to confer lifelong immunity to the virus.

But if the coronavirus that causes COVID-19 is anything like others in the coronavirus family, like the Middle East Respiratory Syndrome (MERS), then permanent protection after infection is unlikely.

Research published in February found that coronavirus patients gained “substantial immune memory” that involved all four major parts of the immune system: memory B cells, antibodies, memory CD4+ T cells and memory CD8+ T cells. This protection lasted about six months after infection in most people, but for some, it remained for up to eight months, suggesting it could last even longer in some cases.

Other research posted in April showed a history of COVID-19 among U.K. patients was associated with an 84% lower risk of reinfection for about seven months after testing positive.

While scientists cannot predict who will develop natural immunity, evidence shows people who had severe COVID-19 are more likely to develop a stronger immune response than those who had milder forms of the disease.

However, studies, like the new CDC research, have found vaccine-derived antibodies are more robust compared to those from previous infection — and the job is done without causing illness or other long-term complications often brought on by the disease.

An April study that has not been peer-reviewed found that two doses of either the Pfizer or Moderna vaccines offered 10 times higher levels of antibodies compared to those developed after previous infection.

Another April paper showed that people who were previously infected with the coronavirus experienced significant boosts in their preexisting antibodies after two doses of the Pfizer vaccine.

Still, “breakthrough cases” can occur because no vaccine is 100% effective.

Breakthrough cases are those that occur two or more weeks after complete vaccination, which is after the second dose for people who got the Pfizer or Moderna vaccines and after a single dose for those who received the Johnson & Johnson vaccine.