Over the last year, we've learned more and more about how to protect ourselves from the coronavirus—through masks, social distancing, and now, vaccinations. Those who have already had COVID and survived have learned that they may be at least somewhat protected thanks to the immunity that comes from prior infection. Unfortunately, the virus can still finds it way in, and there is no way to be 100 percent immune to the coronavirus. Breakthrough infections have been reported after vaccinations, and people who have already had COVID have gotten reinfected. Now, researchers are trying to decipher what cases of reinfection have in common. According to a new study, one of the similarities among people who get COVID again is that nearly all have at least two comorbidities.
A new study preprinted June 13 on medRxiv looks at the characteristics of COVID patients who have tested positive for the virus more than once. Researchers pulled clinical and testing data for 23 patients from a large U.S. electronic health record database. The patients had positive test results at least 60 days apart and separated by at least two consecutive negative test results—making it clear that these were reinfection cases, not cases in which people had prolonged COVID infections.
According to the study, 96 percent of these reinfected patients had two or more comorbidities, which is the simultaneous presence of diseases or medical conditions within a patient. In this study, 70 percent of the patients had hypertension, 26 percent had cardiovascular disease, atrial fibrillation, or chronic kidney disease, and 22 percent had type 2 diabetes or a history of venous thromboembolism or long-term anticoagulation. These are all considered risk factors for COVID by the Centers for Disease Control and Prevention (CDC).
"Based on what we know from similar viruses, some reinfections are expected. We are still learning more about COVID-19," the CDC said in a statement on its website. However, the agency added that while cases of COVID reinfection have been reported, they "remain rare."
But having two or more comorbidities is not the only shared characteristic among patients who get COVID more than once. The researchers also found that 61 percent of the reinfected patients were either overweight or had obesity, 83 percent had immune compromising conditions, and 83 percent also smoked within the prior year. The average age for the patients who were reinfected was around 64 to 65 years.
"Our study demonstrated a high prevalence of immune compromise, comorbidities, obesity and smoking among patients with repeatedly positive SARS-CoV-2 tests," the researchers said.