The Indian Council of Medical Research-National Institute of Virology (ICMR-NIV), Pune, has reported a case of three-time Covid infection in an individual who was vaccinated with the Covishield jab against the virus.
The healthcare professional from Delhi had primary SARS-CoV2 infection, breakthrough infection with Delta and reinfection with Omicron over a period of around 16 months, researchers of Pune NIV said in a study.
The findings of the study prove the immune evasion potential of the Omicron variant, even after infection and vaccination, said the researchers.
The researchers in the report have said that the 38-year-old had tested positive with primary Covid infection during the first wave of the pandemic with symptoms like body ache, fever and a dry cough on October 9, 2020.
However, there were no complaints of breathlessness, and post recovery, he experienced symptoms of long Covid, including generalised weakness for two to three weeks and insomnia for two to three months.
The healthcare professional experienced body ache and headache again in November 2021. Subsequently, he tested positive for SARS-COV-2 and the body ache persisted for two to three days.
However, during the third wave of the pandemic, the individual again developed a headache on January 24, 2022, after being asymptomatic for a period of two months.
The researchers in the report said that the case represented a breakthrough infection post primary SARS-CoV-2 infection and two doses of Covishield vaccination.
The patient received the first dose of Covishield vaccine on January 31, 2021, and the second dose on March 3.
While vaccination reportedly reduces severity of disease and mortality in Covid-19, it cannot protect individuals from getting a breakthrough infection, said the researchers.
The NIV scientists concluded the report saying that the fight against Covid-19 is far from over. Although vaccine boosters or third doses have shown an augmentation in the immune response against the Omicron variant, it has been found to wane over time.
In such a situation, non-pharmacological interventions in the form of mask, hand hygiene and infection control remain the most reliable weapons to curb the direct transmission of SARS-CoV-2, researchers said in the report. The report was published in the Journal of Infection.
