New study reveals extent of innate immunity to COVID

The Guardian made it into a horror story. “Exposure to one nasal droplet enough for Covid infection,” was the headline. 

Around half-way through the article, the discerning reader might notice that only half of those exposed to “one nasal droplet” actually became infected. The Guardian knows, of course, that most readers don’t make it that far.

The article is about an interesting “human challenge” study conducted in the UK on 36 young, healthy volunteers between the ages of 18 and 29, none of whom had evidence of prior COVID infection or vaccination. They all submitted to having wild-type SARS-CoV-2 “intranasally inoculated” and were then placed in quarantine, with constant medical monitoring including regular PCR and lateral flow testing.

After excluding two trial participants who became seropositive after screening, the results were that 18 volunteers (53 percent) became infected. 16 did not.

The viral load in those who became infected rose steeply, peaking at around five days post-inoculation. Viable virus was recoverable from the nose up to 10 days post-inoculation, however – meaning that the volunteers could still transmit the virus to others until that point. 

Not one of the 34 who completed the trial became seriously ill, nor were any adverse events recorded. 12 people developed issues with taste and smell.

The study’s results seemed to encourage use of the much-maligned lateral flow tests, with the authors noting that, “Lateral flow results were strongly associated with viable virus.” These tests picked up on viable virus on average 36 hours after a qPCR test did, but also tended to remain positive for up to three days after no more viable virus was present.

What was especially noteworthy in the study was that, “No quantitative correlation was noted between viral load and symptoms, with high viral loads even in asymptomatic infection [italics added] … our data clearly show that SARS-CoV-2 viral shedding occurs at high levels irrespective of symptom severity, thus explaining the high transmissibility of this infection and emphasizing that symptom severity cannot be considered a surrogate for transmission risk in this disease.”

Now for The Guardian’s take on the study. 

Their opening statement – “one nasal drop enough for Covid infection” – could equally have been, “one nasal drop not enough for Covid infection,” given that almost half of the study participants did not become infected, even though they had the virus literally dropped into their noses.

They then described the volunteers as “healthy, young … with no immunity to the virus [italics added],” without explaining how 16 people with “no immunity” nonetheless proved to be immune to the deadly droplet. 

The Guardian also claimed that lateral flow tests were shown to be “reassuringly reliable” in showing whether infectious virus was present, although returning a positive result three days after the person is no longer contagious is not especially reliable.

Their article also quoted one Professor Wendy Barclay, head of the department of infectious disease at Imperial College London, who warned that, “A lot of people could be walking around shedding virus and not realizing.” Of course, “A lot of people could be walking around immune to COVID and not realizing” too…

Admittedly, The Guardian did concede that there is such a thing as innate immunity (though they avoided calling it by that name), calling the finding “intriguing,” as if it was something doctors and scientists have never heard of before. 

And, not to be left out, Gilead Sciences Inc. got in on the action with a magnanimous donation of remdesivir to be used on trial participants showing symptoms.

The first ten volunteers to have PCR-confirmed infection were given “pre-emptive” remdesivir “with the aim of mitigating any unexpected risk of progression to more severe disease.” 

Interesting – The Guardian made no reference whatsoever to remdesivir. Now, why could that be? Could it possible be because remdesivir failed – once again – to show any clinical benefit?

“Following review by the DSMB and TSC, pre-emptive remdesivir was deemed unnecessary … of the first 10 participants prospectively assigned to receive pre-emptive remdesivir on PCR-confirmed infection, 6 became infected.”

What was more, “No apparent differences were seen in viral load … between remdesivir-treated and untreated infected individuals … With no significant differences between remdesivir-treated and untreated participants, infected individuals were therefore analyzed together.”