In some rare cases, breakthrough infections may lead to persistent symptoms.
“Long Covid” is a poorly understood set of symptoms that can plague people for several months after an active infection has ended. While those symptoms eventually resolve in many patients, “there are this subset of people who have long Covid who just aren’t able to recover at all,” said Akiko Iwasaki, an immunologist at Yale University.
Only a couple of small studies have investigated how common or severe long Covid may be after breakthrough infections. It is likely to be rare, Dr. Iwasaki said, because breakthrough infections are uncommon to begin with and shorter in duration.
In one study in Israel, about seven of 36 people with breakthrough infections had persistent symptoms for more than six weeks. And in a survey of Covid-19 survivors, 24 of 44 people with a symptomatic breakthrough infection reported lingering problems.
“We really need a wider national or even international survey,” Dr. Iwasaki said.
Breakthrough infections may offer an unexpected advantage.
If you get through a breakthrough infection relatively unscathed, you are likely to walk away with more robust protection against variants. The infection essentially acts as a booster shot, researchers say, strengthening your immune system’s ability to recognize and fight the virus.
Studies have shown that when people who recover from Covid-19 receive even one dose of a vaccine, their antibody levels skyrocket. “I expect similar things would happen when you have a breakthrough infection,” Dr. Iwasaki said.
The vaccines train the immune system to recognize a piece of the original virus, a strategy that may leave us vulnerable to future variants. But every exposure broadens the repertoire of immunity, Dr. Mina said.
Eventually, through booster shots or through repeated infections, our bodies will gain an education in the virus sufficient to counter versions with new mutations, he said, adding, “But we’re not there yet.”