Do You Need to Get Vaccinated if You Already Had COVID-19?

Since the beginning of the pandemic, many have wondered whether you needed to get vaccinated after being infected with COVID-19, or if natural immunity would offer enough protection.

Public health experts have continuously stressed the importance of getting vaccinated for broader and longer-lasting immunity, even if you’ve had COVID-19 before. But new research suggests there’s a definite difference between the level of immunity of people who are vaccinated and those who aren’t.

The study, which was published in the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report, analyzed data from 7,000 people who were treated at 187 hospitals in nine states across the country for COVID-like illnesses between January and September of this year. One group had tested positive for COVID-19 at least three months prior to hospitalization, while the other had no history of infection.

All of these patients were tested for COVID-19 and, the data show, people who were not vaccinated against the virus who had recovered from previous infection were 5.49 times more likely to test positive for the virus than people who had been vaccinated in the past three to six months.

“All eligible persons should be vaccinated against COVID-19 as soon as possible, including unvaccinated persons previously infected with SARS-CoV-2," the researchers wrote.

Rochelle Walensky, MD, director of the CDC, released a statement after the report, urging people to get the COVID-19 vaccine.

“We now have additional evidence that reaffirms the importance of COVID-19 vaccines, even if you have had prior infection,” she said.

Previous Research Supports These Findings

As a whole, data has suggested that people receive better protection from being vaccinated against COVID-19. One study from August found that, among Kentucky residents with COVID-19 in 2020, unvaccinated people were 2.34 times more likely to be re-infected than those who were fully vaccinated.

Another study, this one published in June, found that people who had COVID-19 appear to have some level of protection against SARS-CoV-2, the virus that causes COVID-19, for at least a year. However, those who previously had COVID-19 and received at least one dose of an mRNA COVID-19 vaccine had a nearly 50-fold increase in neutralizing antibodies (i.e. antibodies that defend the cells against the virus).

One Israeli study from August found that people who were previously infected with COVID-19 had longer-lasting and stronger protection against COVID-19 compared to people who received the Pfizer-BioNTech COVID-19 vaccine. The study has not yet been peer-reviewed.

However, that study had a few potential issues, Thomas Russo, MD, professor and chief of infectious disease at the University at Buffalo in New York, told Verywell.

“It analyzed people that were unvaccinated but were symptomatic and presented to the healthcare system,” he says. “But the people that we’re most concerned about are those with mild disease. Those we know have the most variable immunity.”

Russo also noted that, when the study was conducted, people who were fully vaccinated “thought they were bullet-proof.”

"They may have taken different risks of exposure compared to the unvaccinated, which appreciated that they might not have optimal immunity,” he said.

Experts Say Get Vaccinated

Doctors say the latest data reinforces the fact that people who have had COVID-19 should get vaccinated against the virus.

“As the time from infection increases, the risk of COVID-19 reinfection increases,” Amesh A. Adalja, MD, infectious disease expert and a senior scholar at the Johns Hopkins Center for Health Security, told Verywell.

Adalja said that natural immunity “does provide significant protection, but it’s not fully clear what its nature may be.”

The CDC study focused on people who were hospitalized with the virus but the findings may not be applicable to those who aren’t hospitalized, he added.

“It’s really important to understand what happens to those who are not hospitalized and how they fare with reinfections," he said. "Does infection confer protection against future hospitalization and how does that compare against the unvaccinated and vaccinated?”

The latest study didn’t include people who received the Johnson & Johnson vaccine, and experts said it’s unclear if those vaccine recipients would have as much of an edge over those who had natural infection.

“The Johnson & Johnson vaccine is a more traditional vaccine and likely would not have been as immunogenic as the mRNA vaccines if studied head-to-head,” Richard Watkins, MD, an infectious disease physician and professor of internal medicine at the Northeast Ohio Medical University, told Verywell.

Russo agreed. “I do think that edge for vaccination would fall if you looked at Johnson & Johnson compared to the mRNA vaccines like Pfizer and Moderna,” he said. “Full protection would likely shrink.”

Overall, "it’s becoming clear that those with prior infection would benefit from just a single dose of vaccination to shore up whatever immunity they have acquired naturally," Adalja said.

Russo urged people who have had COVID-19 to not rely on natural immunity alone for protection.

“Vaccine-induced immunity is more protective,” he said. “If you go ahead and get vaccinated, you’ll have a degree of immunity that will be better than those who have never been infected.”

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.