Most people who contract Covid-19 still have antibodies at least six months after the infection, a new study of more than 20,000 people showed.
Some 88% of participants who tested positive for a previous infection maintained antibodies for six months, according to the report by RA Biobank, a major biochemical database. The number was 99% at three months.
The results continue other studies, less showing an immune level after a natural infection for at least 6 months. Health officials have said it is not yet clear how long protection through vaccines can last, and the rise of viral rays could mean the pictures may need to be updated from time to time for effectiveness to maintain.
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The study ran from late May through early December, based on monthly blood samples and data on possible symptoms from Biobank participants, their adult children and grandchildren.
The most common symptom associated with receiving antibodies to Covid was loss of taste and smell, which was reported by 43% of participants. About a quarter were completely asymptomatic.