I assume conspiracy theories are already circulating on Facebook that there was no actual “adverse reaction” in this study. It’s just the darned deep state again, cooking up a pretext to go slow on vaccine development so that Trump doesn’t get the “October surprise” he’s clearly pining for.

In reality, this looks like a textbook example of why going slow is the responsible approach. As I understand it, phase one of vaccine trials is a *basic* safety test: A few dozen people get the shot just to make sure that no one keels over upon receiving it. The real safety test comes in phases two and three, though, as the number of participants balloons. Unexpected side effects that might not have showed up in the small phase-one group purely by chance are more likely to show up when you’re testing on 30,000 people or whatever. Hence the shudder that went through the planet yesterday when news broke that someone enrolled in AstraZeneca’s trial of the Oxford vaccine had developed a serious enough adverse reaction that the entire study had to be paused. Oxford is the leader of the pack in vaccine development, ahead of everyone else in the western world. If their product’s too risky to use, it’s a setback.

And potentially, if their product is causing a serious side effect, other vaccines in development like Moderna’s and Novavax’s might have the same problem. Which would be a lot worse than a “setback.”

Bear in mind that Russia isn’t even doing phase-three testing. They rang the bell after phase two and told the Russian public to come and get it.

The spokesperson described the pause as “a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials.” The spokesperson also said that the company is “working to expedite the review of the single event to minimize any potential impact on the trial timeline.”

An individual familiar with the development said researchers had been told the hold was placed on the trial out of “an abundance of caution.” A second individual familiar with the matter, who also spoke on condition of anonymity, said the finding is having an impact on other AstraZeneca vaccine trials underway — as well as on the clinical trials being conducted by other vaccine manufacturers.

Every story about this on the wires today is careful to note that pausing a clinical trial has been known to happen. All it means is that someone enrolled in the study developed a serious illness. It’s possible that that illness is unrelated to the vaccine; in fact, one of the first things AstraZeneca will do is try to figure out whether the sick participant actually received the vaccine or a placebo. If it’s the latter, there’s no problem. Full speed ahead. If it’s the former, they need to make a judgment about whether it’s likely or not that the vaccine is related to the illness.

The Times’s report contains this ambiguously worded detail:

A person familiar with the situation, and who spoke on the condition of anonymity, said that the participant had been enrolled in a Phase 2/3 trial based in the United Kingdom. The individual also said that a volunteer in the U.K. trial had been found to have transverse myelitis, an inflammatory syndrome that affects the spinal cord and is often sparked by viral infections. However, the timing of this diagnosis, and whether it was directly linked to AstraZeneca’s vaccine, is unclear.

Reading that, I thought they were claiming that myelitis is what triggered this new study “pause.” But maybe not: A Twitter pal points to this passage in another story by the magazine Nature.

It is the second time that administration of the vaccine has been paused in the UK, according to two people who took part in the study and to information sheets uploaded to a clinical trial registry. Previously, a participant developed symptoms of transverse myelitis, an inflammation of the spinal cord which is often sparked by viral infections, according to an information sheet given to trial participants dated 12 July. After a safety review, the trial resumed. The individual was diagnosed with an “unrelated neurological illness”.

So myelitis caused the first “pause.” Is the Times claiming that myelitis also caused this new, second pause? Because that would be an “uh oh” moment and might cause researchers to revisit their assessment that the first myelitis case was unrelated to the vaccine. Or is the current pause due to some other disease, one which might reasonably be explained as unconnected? A lot rests on the answer. A doctor who advises the FDA told NBC that study pauses due to suspicions of serious side effects are “uncommon, but not unheard of,” and expects that we’ll know the cause in a few days.

What if all of the vaccines go bust? Well, a new theory has emerged that we already have a type of crude vaccine in our possession: Masks. The idea is that, although masks mainly protect people around you from being infected by you, they can also block *some* viral particles spewed by others before they enter your nose and mouth. “Some” is the key here. If it’s true that someone who inhales a smallish viral load will develop a mild or asymptomatic case of COVID (and scientists have, er, no idea if that’s true) then in some cases the filtration process provided by the mask is working to “vaccinate” people. Enough of the virus is getting through to your system to evoke an immune response but not enough is getting through to actually get you sick, at least not with serious symptoms.

Laying aside the fact that this theory rests on various unproven assumptions, would popularizing it actually do more harm than good?

Taken the wrong way, the idea could lull the masked into a false sense of complacency, potentially putting them at higher risk than before, or perhaps even bolster the incorrect notion that face coverings are entirely useless against the coronavirus, since they cannot render the wearer impervious to infection.

“We still want people to follow all the other prevention strategies,” Dr. Popescu said. That means staying vigilant about avoiding crowds, physical distancing and hand hygiene — behaviors that overlap in their effects, but can’t replace one another…

[I]t is difficult to pin down the infectious dose required to sicken a person, Dr. Rengarajan said. Even if researchers eventually settle on an average dose, the outcome will vary from person to person, since factors like genetics, a person’s immune status and the architecture of their nasal passages can all influence how much virus can colonize the respiratory tract.

How anyone is supposed to convert this theory into sound pandemic practice escapes me. Let’s say, hypothetically, that absorbing 100 viral particles is enough to evoke an immune response without symptoms whereas absorbing 1,000 viral particles will produce symptoms. Imagine masking up and standing next to someone who’s in the early stages of a symptomatic case — cough, very mild fever, etc. Whether you get sick or not would depend on how many particles the infected person is coughing into the air and on how effectively your mask filters those particles, both of which would be hugely variable. You’d be nutty to take your chances in that situation just because you’re wearing a mask.

But then, the theory isn’t really prescriptive. It’s descriptive, a possible explanation for why there are so many asymptomatic cases out there (and why there are fewer hospitalizations now than there were when the first wave hit in March). Masks aren’t foolproof in protecting people from serious infection but they might be “protective enough.”