Researchers from Icahn School of Medicine at Mount Sinai found that both groups equally reported experiencing pain, swelling, and redness at the injection site at the time of vaccination, which improved in a couple of days. However, people with a prior infection experienced more severe systemic reactions—fever, headache, chills, muscle or joint pain, and fatigue—than those who had never been infected.

“We also noted that vaccine reactogenicity [expected reactions] after the first dose is substantially more pronounced in individuals with pre-existing immunity akin to side-effects reported for the second dose in the phase III vaccine trials [of both Pfizer-BioNTech and Moderna],” the researchers stated.

A severe systemic reaction to a vaccine “prevents daily activity,” according to the Food and Drug Administration (FDA).

The study also looked at the immune system’s response to the vaccines in 109 people: 41 who had recovered from COVID-19 and 68 who’ve never had the disease, and found those in the recovered group had “10-20 times higher” antibody levels than those who had never been infected.

More studies are needed to further investigate the study’s findings due to the small number of participants.

Some scientists and doctors are questioning why people with prior CCP virus infection still need to get the vaccine when they already have some measure of immunity against the virus especially when there’s a limited number of vaccines available.

The CDC says people should be vaccinated whether or not they’ve had COVID-19, the disease caused by the CCP virus.

“Due to the severe health risks associated with COVID-19 and the fact that reinfection is possible, CDC recommends getting vaccinated regardless of whether you already had COVID-19 infection,” a spokesperson from the CDC told The Epoch Times in an email. “Experts do not yet know how long someone is protected from getting sick again after recovering from COVID-19.”

“However, because the risk of reinfection is low in the months after initial COVID-19 infection, while vaccine supply remains limited, people who have a recent infection may choose to temporarily delay vaccination,” the spokesperson added.

But opponents say that the possibility of reinfection is rare, so vaccines shouldn’t be promoted to those with prior infection.

Some health care personnel are declining a COVID vaccine, citing concerns of side effects, vaccine safety, and efficacy, the speed at which the vaccine was developed, and a lack of trust.

According to the hospital’s CEO, Tim Egen, last month, 75 percent of their staff have refused to get the shot.

“We’re trying to overcome some pretty prominent hurdles—you know, a lack of trust in the medical testing,” he told CBSN Chicago.

The authors said research scientists and doctors showed “the highest acceptance” in the 58 percent group, and respondents who were “older, males, White, or Asian were more likely to get vaccinated compared to other groups.”