A medical student from Kerala’s Thrissur district, who was the first Indian to test positive for the coronavirus disease last year, has once again contracted the infection, the Hindustan Times reported on Tuesday.

“She has tested positive and is under quarantine at her home,” Thrissur District Medical Officer KJ Reena said. “None of the family members have tested positive so far.” Reena said that the woman is asymptomatic.

The 20-year old, who was a medical student in China’s Wuhan city, the epicentre of the outbreak, had first contracted the infection in January 2020. She returned to her home in India on January 24 last year. She soon developed mild flu-like symptoms and was admitted to a local hospital.

After she tested positive for the coronavirus disease on January 30, 2020, she was moved to the Thrissur Medical College. Two of her friends, who returned with her from Wuhan, had also tested positive for the virus.

This time, she was detected with the virus in a routine test as she was planning to travel to Delhi.

Last year, the Indian Council of Medical Research had said that a person may get reinfected with Covid-19 if antibodies against the infection reduce within five months after recovery.

According to the United States’ Centers for Disease Control and Prevention, the probability of a reinfection is expected to increase with time after recovery from initial infection because of waning immunity and the possibility of exposure to virus variants. Mutant strains may cause reinfection as a person may not have antibodies against them despite having contracted the virus, the CDC said.