Some seemingly recovered COVID-19 patients have re-tested positive, according to anecdotal reports. But most of what the medical community knows about how the novel coronavirus works indicates that once a person recovers from coronavirus they develop some sort of sustained immunity.
Those who re-tested positive could have not fully recovered before the test was re-administered, and it’s possible for a test to show a false positive, Dr. Maher Balkis of Cleveland Clinic Abu Dhabi told Al Arabiya English. In these few cases, it’s also impossible to know if they were clinically cured and testing positive twice may be an anomaly.
“Unfortunately, the virus that causes COVID-19 is so new that we simply do not have a clear picture,” Balkis, who is an associate staff physician of infectious diseases told Al Arabiya English.
While those who catch coronavirus and recover likely develop an immunity, how long that immunity may last is another question.
“As we continue to study this novel coronavirus, we will learn more about how it works, how it can be treated and how long any immunity might last,” Balkis said.
The scientific community still does not know how long natural immunity to coronavirus – one that is developed from contracting COVID-19 and surviving – may last. But testing for immunity – as opposed to infection – has already begun in parts of Asia and could soon become vital for the rest of the world. Germany has begun issuing immunity certificates, and those with their newfound immunity are allowed to re-enter society.
“We can’t know how long natural immunity would last, but we have reason to suppose based on prior coronaviruses that it will be sustained,” Dr. Nicholas Christakis, a physician and professor of social and natural science at Yale University told Al Arabiya English.
Other viral infections, like the flu and other coronaviruses, have varying time periods in which a person is immune, and what is known about past coronaviruses, like SARS, may or may not be applicable to COVID-19.
“We find serologic – like a blood test – evidence of immunity for up to a year for SARS, but we think you’re still immune in a different way for a longer time,” explained Christakis.
Other viral infections, like the common cold, induce an immunity for around three months, Dr. Maher Balkis, associate staff physician for infectious diseases at Cleveland Clinic Abu Dhabi told Al Arabiya English.
For the flu, a vaccine is needed annually because the immunity created only lasts a year, explained Christakis.
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