In a new report, the Centers for Disease Control (CDC) said that while both infection and vaccination induce an immune response that can last more than six months, vaccination provides a “higher, more robust, and more consistent level of immunity to protect people from COVID-19 than infection alone."
The CDC published an overview of the current data on infection-induced and vaccine-induced immunity to COVID-19, which includes evidence from more than 90 peer-reviewed and pre-print publications, as well as unpublished data from the CDC.
More than 46 million Americans have had confirmed COVID-19 infections. By some estimates, more than half of COVID-19 cases have gone unreported.
About half of the previously infected U.S. adults have not been vaccinated, according to a survey of antibody levels and history of vaccination among blood donors between January and August.But the antibody response for unvaccinated individuals depends on how sick they were and other factors.
“Given the variability of the immune response to infection, likelihood of waning immunity, and on-going high rates of SARS-CoV-2 nationally, it is important that all eligible persons be vaccinated as soon as possible, including those with a history of COVID-19,” Catherine Bozio, PhD, MPH, an epidemiologist at the CDC, told Verywell via email.
People with Natural Immunity Are More Likely to Be Hospitalized For COVID-19
In a separate study, CDC researchers analyzed data from people hospitalized with COVID-19-like symptoms. One cohort had tested positive for COVID-19 at least three months prior to hospitalization, while the other had no history of infection.
Unvaccinated adults who had recovered from the illness were 5.5 times more likely to test positive for COVID-19 than those who are vaccinated, according to the study.
Other recent studies align with these findings. An October study published in The Lancet Microbe found that unvaccinated individuals had a 50% chance of being reinfected by about 17 months after the initial infection.
Do You Really Need the Vaccine if You’ve Recovered From COVID-19?
When infected with a pathogen, like the COVID-19 virus, the immune system spurs the creation of various protective cells, like neutralizing antibodies and memory cells.
Studies show that neutralizing antibodies indicate protection, but scientists aren’t exactly sure the levels of antibody necessary for individual immunity. Other kinds of antibodies and immune cells are also important for preventing COVID-19 and limiting severe outcomes, but scientists have yet to draw a direct correlation between them.
According to the CDC report, 100% of participants who received the Pfizer or Moderna vaccines and 90% of those receiving the Johnson & Johnson shot in clinical trials developed both binding and neutralizing antibodies. These vaccines typically lead to “a more consistent" antibody response than that of COVID-19 infection.
The levels of antibodies induced by natural infection can vary widely from person to person. People who are asymptomatic or experience only mild illness typically produce fewer neutralizing antibodies than those with more severe illness.
In addition, people who were infected with the original strain of the virus tend to have lower levels of immunity against later variants like Delta.
For children aged 5 to 11, who are now eligible for the Pfizer COVID-19 vaccine, getting the shot may be especially important, said Bozio. According to CDC data, nearly 40% of children in this age group have been infected with COVID-19.
“Although this has not been studied well in children, comparing seroprevalence to reported cases in children, it appears that children may have a much higher rate of mild or asymptomatic infection than adults,” Bozio said. “This group may be even more vulnerable to reinfection, and should as a result be strongly encouraged to be vaccinated.”
There’s no test authorized by the FDA that would tell an individual or healthcare provider an individual’s level of protection. Since experts don’t yet know the necessary antibody levels to prevent reinfection, the CDC authors wrote that antibody tests are unreliable for indicating whether an individual is protected.
Ultimately, being vaccinated will likely protect you against COVID-19 infection and serious illness more consistently than natural infection. If you’ve recovered from COVID-19, getting vaccinated will further reduce the risk of reinfection.
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.
