COVID-19 re-infection: a large cross-sectional population-based study in the northeast of Iran

Today, COVID-19 reinfection has raised further public health concerns than its primary infection; which make major global health concern that going to the possibility of COVID-19 re-infection, and how strong the body's immunity against this disease in individuals with the previous infection. The present study aimed to investigate the probability of COVID-19 re-infection leading to hospitalization in the population referred to hospitals affiliated with Mashhad University of Medical Sciences, Mashhad, Iran.

The present cross-sectional epidemiological study was conducted on patients referred to hospitals affiliated to the Mashhad University of Medical Sciences, Mashhad, Iran supervision with re-infection of COVID-19 from January 21, 2020, to August 23, 2022. The patients had a definite diagnosis through RT-PCR testing in their first and re-infections, with a time interval of at least one month between the two episodes of infection.

Out of 125,857 patients evaluated, 9,710 (7.7%) were readmitted with COVID-19 infection more than once, with a time interval of more than one month from their previous hospitalization. The average age of hospitalized patients was 54.8 ± 22.97 years, and more than half were men (51.4%). The most common underlying diseases were hypertension (19.4%) and diabetes (14.8%). cardiovascular diseases, asthma, and cancer were the strongest independent risk factors of COVID-19 re-infection (OR = 2.53, 2.47, and 2.36, respectively, p < 0.001 for all cases).

In conclusion, our study demonstrates the importance of understanding the risk factors associated with COVID-19 re-infection and re-hospitalization, particularly in vulnerable populations with comorbidities and substance use disorders.