What is Paxlovid, the antiviral that Biden is receiving?
0:48
(CNN Spanish) --
The contagion of covid-19 of the president of the United States, Joe Biden, is leaving some with more questions than answers.
After testing negative for the disease, Biden again tested positive for the virus in what is known as the "Paxlovid rebound."
Why is this happening?
Contrary to what some think, it is not a reinfection of covid-19, but a phenomenon that science had previously detected.
Dr. Elmer Huerta explains us in this episode.
You can listen to this episode on Spotify or your favorite podcast platform, or read the transcript below.
Hi, I'm Dr. Elmer Huerta and this is your dose of information about the new coronavirus.
Information that we hope will be useful to take care of his health and that of his family.
On July 21, the president of the United States Joe Biden contracted covid-19 -caused by the BA.5 subvariant- and his illness caused three sobering medical phenomena that we will see today:
advertising
The first, being infected while fully vaccinated and with a booster dose;
The second, the Paxlovid rebound;
And third, the persistence for several days of the positive antigen test for the SARS CoV-2 virus.
Being infected with covid-19 being fully vaccinated
Getting infected while fully vaccinated and with booster doses, that is a very common phenomenon in infections caused by the omicron virus family.
As we have heard in previous episodes, the viruses of the ómicron family have two fundamental characteristics:
On the one hand, they mock antibodies produced by natural disease or vaccines
And, for another, they are extraordinarily contagious.
The fact that the virus evades antibodies is manifested in that a person can get sick two, three and even four times, even after having already suffered from the disease or having been vaccinated, including boosters.
In this regard, it is not uncommon to hear people skeptical of vaccines who ask themselves: If I am still going to get infected if I get vaccinated, then why do I get vaccinated?
We have also heard the answer in previous episodes of this podcast.
Unfortunately, vaccines -as in the case of President Biden- do not protect us from infections, but -as is the case with him- they do protect us from the disease becoming more complicated and ending up in the hospital.
The purpose of the vaccine is, then, to put it in simple words, to avoid complications and death.
The Paxlovid Bounce
Now let's look at the second phenomenon, the Paxlovid rebound.
As we heard on the June 10, 2022 episode, Paxlovid is a drug that contains two antiviral drugs:
Nirmatrelvir, which acts directly on SARS-CoV-2,
And ritonavir, which, despite not having a direct action on SARS-CoV-2, is included because by increasing the concentration of the first drug, it makes it more effective in its antiviral action.
In studies conducted to demonstrate its usefulness, the Pfizer laboratory published results showing that treatment with Paxlovid - started within the first days of presenting the first symptoms - reduces the risk of hospitalization or death by 89% in adults who have a high risk of complication.
That is why Paxlovid is indicated in older adults and in people of any age, who suffer from a disease that can lead to complications.
President Joe Biden's covid-19 infection
With this criterion, and due to his age, Biden —79 years old— received a 5-day course of Paxlovid, which he completed from July 21 to 25, reporting halfway through his treatment —on July 23— that he had improved and was working.
According to the isolation guidelines of the Centers for Disease Control and Prevention of the United States, the CDC, for its acronym in English, the president had a negative test on the fifth day of illness, after finishing Paxlovid, for which on Tuesday, July 26, was discharged, returning to work from Wednesday, July 27, observing a more frequent use of a mask.
At the direction of his doctor, Biden took daily tests, both during his treatment with Paxlovid and after finishing it, coming out negative on July 27, 28 and 29.
However, the surprise occurred on Saturday the 30th in the morning when the doctor reported that, despite the fact that the president had no symptoms, the test that day had come out positive, so —according to the CDC guidelines— the president had to isolate himself again until his test comes back negative.
President Biden was then diagnosed with rebound by Paxlovid, and according to the CDC guidelines, he had to start a new period of isolation, but without needing a new course of treatment.
Use of Paxlovid against covid-19 would cause expansion of the virus 1:59
Is this rebound phenomenon new?
As we heard on the June 10 episode, the rebound phenomenon had already been documented in clinical studies done to test the effectiveness of Paxlovid.
In Pfizer's application to the FDA for approval of the drug, it was found that "a small number" of participants who had a negative molecular test after completing five days of treatment, returned positive a few days later.
This finding was seen in both people given Paxlovid and people given placebo.
It is possible that the rebound could be a consequence of still unknown mechanisms related to the infection.
Regarding the frequency with which Paxlovid rebound occurs, a preprint by American authors on June 22 provides some interesting information.
The authors studied rebound in 13,644 patients.
They were diagnosed with covid-19 between January 1 and June 8, 2022, and received Paxlovid or the antiviral molnupiravir.
The bounce classes
Rebound was classified into three groups:
return of the infection,
return of symptoms
And hospitalization.
And it was studied in two moments: at 7 and 30 days after finishing the treatment.
The results indicated that the rebound of infection with Paxlovid was:
3.53% at 7 days,
And 5.40% at 30 days,
Finding a symptom rebound of 2.31% and 5.87% on the same days and 0.44% and 0.77% for hospitalizations.
Statistical analysis showed that there were no significant differences in the risks of rebound between Paxlovid and Molnupiravir.
The study has been criticized as "out of time" by some experts because it does not include a sufficient number of cases of the BA.5 subvariant, the predominant one these days in the United States and the world.
It is possible, say some, that the rebound phenomenon is much higher than what the studies say.
Why does a person keep testing positive for antigens?
Let us now look at the third phenomenon, the persistence of positive tests for covid-19.
Surprisingly, and since he had a positive test on Saturday, July 30, President Biden presented positive antigen tests on July 31, and on August 1, 2, 3, 4 and 5, only having a negative test on Saturday 6 , exactly one week after his first positive test after Paxlovid.
President Biden was definitely discharged from this unique episode of 7 consecutive positive antigen tests.
This occurred after giving a second negative test on Sunday, August 7.
Let us remember that an antigen test -which detects virus coat proteins- is not the same as a PCR or molecular test.
According to CDC guidelines, many people may have positive PCR molecular tests for up to three months after being discharged, not having been shown to be contagious.
It is likely that, due to their sensitivity, these PCR tests can recognize non-infectious viral particles, so they should not be used to discharge a patient.
That's why—even though the CDC doesn't recommend testing after completing isolation—many people, including President Biden, get an antigen test, which can also, as we've seen, be persistently positive, not consensus having been reached to determine if the person is still contagious and therefore should be isolated.
What should be done?
Some experts recommend that the persistently positive person, such as President Biden, remain isolated.
Others propose that contact with people who may be vulnerable to complications should be avoided if they are infected.
Since this is a very recent phenomenon, the CDC does not yet have a clear recommendation, so we think that the resolution of President Biden's case will shed light on what the experts think.
In summary, the case of President Biden shows us three sobering phenomena: becoming infected while fully vaccinated, rebounding to Paxlovid, and having persistent antigen tests for a full week.
Do you have questions about covid-19?
Send me your questions on Twitter, we'll try to answer them in our next episodes.
You can find me at @DrHuerta.
If you find this podcast useful, make sure to subscribe to get the latest episode on your account.
Help others find it by rating and reviewing it on your favorite podcast app.
And for the most up-to-date information you can always go to CNNEspanol.com.
Thanks for your attention.
coronavirusCovid-19Joe BidenPaxlovid