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New study in Lancet says viral load and therefore infectiousness is highest in early symptomatic patients

2020-03-30

(image courtesy of pixabay.com)

A new study in the Lancet, reported in the International Business Times, examined 23 patients in Hong Kong with viral load counts.  Viral loads indicate how much virus a person is excreting into his or her environment, therefore how infectious they can be.  Saliva examination measured the amount of SARS-COV-2 a person puts out, and found that the load is highest when symptoms first appear.  22 of the 23 patients had fever, suggesting that they had more than mild disease, although only ten had “severe disease” (two died).  Four of the ten with severe disease had high blood pressure (hypertension).

The presence of early high viral load is different from other coronaviruses like MERS and SARS, in which viral load is highest much later in the course of illness (about ten days).  This early presence of high levels of virus is also seen in influenza, in which patients are contagious at symptom onset.  Viral load declines as the illness progresses, but virus RNA is still detectable for 20 days in one-third of patients, when they are recovering.  Old age appears to be linked to higher viral load, meaning older patients are probably more infectious.

Dr. Yuen, whose team conducted the study, said that the results show that SARS-COV-2 is easily transmitted even when symptoms are mild.  The presence of RNA traces during recovery may not indicate that recovering patients are still infectious; cell culture is required to determine whether those traces are actually effective at transmitting infection.  One result that is confusing but not discussed was that three patients did not have detectable virus RNA but developed antibodies.

The study report states that its results argue for “early use of potent antiviral agents” (eg, remdesivir)– because high viral loads are present early in the course of disease.  This is unlikely to happen if individual cases are forced to be processed through the red tape involved in non-FDA-approved uses of investigational drugs.  I argue that remdesivir should receive an immediate emergency approval for use from the FDA to eliminate the red tape involved in using investigational drugs.  Instead, the FDA has approved chloroquine (a questionably effective and highly toxic drug), probably under pressure from Himself.  Lopinavir, ritonavir, ribavirin, or interferon 1b was given to most of these patients, but these drugs did not have any appreciable effect.

Another study published in the American Journal of Respiratory and Critical Care Medicine and reported in the International Business Times says that 50% of patients continued to shed virus after their symptoms had disappeared.  Shedding times are longer in patients with more severe illness.  Dr. Sharma, the study’s lead author, is at the Yale School of Medicine, but the sixteen patients studied were hospitalized at the People’s Liberation Army General Hospital Treatment Center in Beijing, China.  The time from infection to manifestation of symptoms (the incubation period) averaged five days, and the average duration of symptoms was eight days.  Patients were said to remain “contagious” for one to eight days after symptoms disappeared, but again cell culture to determine infectiousness as opposed to mere shedding of fragmentary, nonviable virus was not performed.

These studies show that the virus can appear in saliva on the first day of illness or even hours before, and high viral loads suggest extreme contagiousness early in the disease.  This means that the virus will be impossible to contain, even with isolation of most of the population, and people worried about getting sick should isolate themselves from everyone. Even those who appear to be well may be carrying high loads of virus and infecting others without realizing it.

After the acute illness has subsided, about half of patients continue to shed some virus.  There have been reports that apparently recovered patients have transmitted the infection to others, but how many can do so is unknown and is not being systematically studied.  Such a post-recovery study would be difficult to perform because it would require susceptible people to expose themselves, perhaps knowingly, to convalescent patients.

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