Are COVID re-infections worse than a first infection?

Data and Metrics Infectious Diseases

No, not for most people. But for vulnerable people, repeated infections can still be dangerous. And each infection carries its own risk of Long Covid.

TL;DR: Repeated COVID-19 infections are neither destroying our immune systems NOR completely harmless. Like many things with COVID-19, the truth lies somewhere in between.

The SARS-CoV-2 virus is here to stay in human populations. This means most people have already been or will be infected multiple times over their lifetime. What this means for human health is unclear, but social media has (as usual) amplified polarized viewpoints. We are hearing either the familiar refrain that COVID is no worse than a common cold OR that each COVID-19 infection is doing irreparable damage to our immune system.

The data are more nuanced.

Studies show that most people with a mild first infection have mild subsequent infections, which are cleared more quickly. This suggests our immune system is doing its job, recognizing the virus and deploying defenses quickly. If COVID-19 were systematically damaging our immune systems, we’d expect subsequent infections to be worse than the first. Re-infections are also much less likely to result in hospitalization or death than first infections (but only for those who survived their first infection). Severe re-infections do happen, and they are more common in people with a severe first infection—likely the most vulnerable people. The death toll from COVID-19 is still higher than a bad flu season, so it is not yet a “common cold.”

One headline-grabbing study using data from the US Veterans health system was interpreted by some to say that additional infections are *worse* than the first, but this is not what it showed. The study found that patients with multiple confirmed infections had worse health (as measured by hospitalizations, heart attacks, and other illnesses over follow-up) than patients with only one confirmed infection. The design of this study has been criticized since only people ill enough to be tested through the medical system would show up as a confirmed case. People with mild re-infections were likely underrepresented, while frailer patients with more severe re-infections were overrepresented. The study is also subject to “reverse causality”—meaning that people who were sicker to begin with were more likely to get re-infections (and also be sicker over the follow-up period).

Still, it makes sense that getting infected twice is worse than getting infected once-like falling off your bike twice is worse than falling off once. This doesn’t mean that the 2nd infection is *more* severe, just that there is an additional opportunity for the virus to cause damage in some way. This may also be true for Long Covid. While the risk of Long Covid is lower with a re-infection (and after vaccination), there is still a risk with each infection.


Every new infection with COVID-19 carries some risk. That means it’s wise to take steps to reduce the number of times you are infected. But overall, our immune systems are acting as expected, and re-infections are milder than initial infections.

Even if you were previously infected, if you are high risk, you should be careful. You can reduce your risk through updated booster vaccinations, prevention measures like masking in crowded indoor spaces, and taking Paxlovid if infected.

Stay safe, stay well.


Those Nerdy Girls