There is no known limit to how many times a person can get COVID-19. People have been documented with two, three, four, and even more infections since the pandemic began. In a large study tracking over 200,000 people with reinfections, most had caught COVID twice, but a smaller group had confirmed infections three or more times. As the virus continues to evolve, reinfection has become a normal part of the landscape rather than a rare event.
Why Reinfection Keeps Happening
The virus that causes COVID-19 mutates rapidly, especially in the spike protein that your immune system learns to recognize. The Omicron variant, for example, carried 34 amino acid changes in its spike protein compared to the original virus. Each new subvariant introduces additional mutations that help it slip past antibodies you built from a previous infection or vaccination. Data from Imperial College London found that Omicron carried a 5.4-fold higher risk of reinfection compared to the Delta variant, largely because it could dodge existing immune defenses so effectively.
Subvariants within Omicron also differ meaningfully from each other. BA.1 and BA.2 shared 21 mutations but each carried unique ones as well, giving them distinct abilities to evade different antibodies. Later subvariants like BA.4 and BA.5 were roughly 4.5 times more resistant to antibodies from triple-vaccinated individuals than BA.2. This constant reshuffling is why someone who caught one version of COVID can catch a newer version months later.
How Long Immunity Lasts After an Infection
Protection from a previous COVID infection is strong but temporary. A large meta-analysis published in The Lancet found that prior infection provided roughly 88 to 90% protection against reinfection from the Alpha, Beta, and Delta variants. That protection begins to weaken noticeably after about eight months, and it drops further when a new variant emerges that looks significantly different from the one you caught.
Reinfection can technically occur as early as several weeks after recovery, though this is rare. The CDC uses a threshold of 90 days between two positive tests (with at least one negative test in between) to formally classify something as a reinfection rather than lingering virus from the first illness. In research settings, many studies use a shorter window of 45 to 60 days.
Vaccination Plus Prior Infection Offers Stronger Protection
People who have both recovered from COVID and been vaccinated develop what researchers call hybrid immunity, and it outperforms either natural immunity or vaccination alone. Against the Delta variant, prior infection alone provided about 90% protection against reinfection. Adding two vaccine doses pushed that to roughly 94.5%, and three doses brought it to 98.1%. This pattern held across multiple variants.
Hybrid immunity doesn’t make you invincible, especially as newer variants continue to evolve. But it does meaningfully reduce your chances of catching COVID again and, perhaps more importantly, reduces the severity if you do.
Are Reinfections Milder Than First Infections?
The answer depends on which data you look at, and individual circumstances vary widely. A large population study in Serbia covering 2020 through 2022 found that reinfections were substantially milder overall: 7.95% of first-time infections led to hospitalization, compared to just 1.08% of reinfections. Fatal outcomes during reinfection were rare.
However, a separate study from the National Heart, Lung, and Blood Institute involving over 200,000 reinfection cases suggested that reinfections can be similar in severity to the original infection. The difference likely comes down to timing, variant, vaccination status, and underlying health. A healthy vaccinated person catching a mild variant for the second time will generally fare well. Someone with chronic health conditions facing a more aggressive variant may not.
Cumulative Health Risks From Repeat Infections
One of the more concerning findings in recent years is that the health toll from COVID appears to accumulate. Researchers at Washington University School of Medicine found that each additional infection adds new risk of organ problems, both in the first 30 days and in the months that follow (the period associated with long COVID).
Compared to people who had COVID only once, those with repeat infections were twice as likely to die and three times more likely to be hospitalized. The organ-specific risks were striking: 3.5 times more likely to develop lung problems, three times more likely to experience heart conditions, and 1.6 times more likely to have brain-related complications. The risk appeared to increase with each subsequent infection rather than plateauing.
This doesn’t mean every reinfection will cause serious harm. Many people recover fully from multiple bouts. But it does suggest that treating reinfections as trivial because “you’ve already had it” may underestimate the cumulative biological cost, particularly for the lungs, heart, and brain.
What This Means in Practice
Most people will catch COVID more than once over the course of their lives. The virus is now endemic, and no combination of prior infection and vaccination provides permanent protection. The practical question isn’t whether you’ll be reinfected but how often and how severely.
Staying current with vaccinations remains the most effective way to reduce both the likelihood and severity of each new infection. The combination of natural immunity from past infections and updated vaccines consistently provides the strongest protection available. Given the evidence that health risks accumulate with each infection, spacing out your exposures and reducing their severity when possible carries real long-term value.