Explainer: Why Joe Biden has tested positive for Covid-19 twice

US President Joe Biden coughing

US President Joe Biden coughing on July 15, 2022 as he speaks to the traveling press after taking part in a working session with Saudi Arabia's Crown Prince Mohammed bin Salman. President Biden on July 30, 2022 tested positive for Covid-19 again.

Photo credit: Mandel Ngan | AFP

The first positive test for Covid-19 is chilling. A second one, days after testing negative, is frustrating.

US President Joe Biden knows this too well.

He had been vaccinated and double-boosted, but before anti-vaxxers question the vaccine’s efficacy, they need to know about a concept called breakthrough infections.

Ideally, a vaccine is meant to stop people from getting severe infections, but it does not stop them from being infected if they come into contact with the virus. Breakthrough infections mean that someone can still be infected even when they have been vaccinated.

About a week ago, President Biden had his first breakthrough infection and media reports indicated that he had mild symptoms.

He recuperated quickly and tested negative for about four days, according to the White House physician, Dr Kevin O’Connor. On Saturday morning, he took an antigen test and was found positive for Covid-19, again.

Dr O’Connor described this as a “rebound case”. Other scientists call this phenomenon a relapse.

“The President has experienced no reemergence of symptoms and continues to feel quite well. This being the case, there is no reason to reinstate treatment at this time, but we will obviously continue close observation,” said Dr O’Connor in a statement.

Reinstate strict isolation procedures.

“However, given his positive antigen test, he will reinstate strict isolation procedures.”

While on treatment, President Biden was given an antiviral drug called Paxlovid. The drug was given emergency use authorisation by the US Food and Drug Administration in October last year. In July, pharmacists in the US authorised licensed pharmacists to prescribe it to patients.

The US Centres for Disease Control and Prevention (CDC) explained in its advisory that a rebound occurs when there is a resurgence of Covid-19 between the second and the eight day after initial recovery. It can be identified by either Covid-19 symptoms or a new positive test after previously testing negative.
“A brief return of symptoms may be part of the natural history of SARS-CoV-2 (the virus that causes Covid-19) infection in some persons, independent of treatment with Paxlovid and regardless of vaccination status,” explains the CDC.

“Limited information currently available from case reports suggests that persons treated with Paxlovid who experience Covid-19 rebound have had mild illness; there are no reports of severe disease.”

An article in the scientific journal BMJ, however, says that most people who have had rebounds even after taking Paxlovid feel better three days after the new positive test. Even during the trials for the drug, some patients, about two per cent, still tested positive days after getting a negative Covid-19 test.
But a rebound case should not be confused with or used in place of long Covid, whose sufferers are also known as Covid-19 long hauliers.

While the two are almost the same, long Covid refers to a situation where someone who previously had Covid-19 and tested negative still has lingering symptoms for months.