The China jogger outbreak study is not believable because it isn’t plausible. Let’s stop citing it to confirm our own biases.

It is widely known that outdoor transmission is possible, but it occurs less often and requires close, sustained contact.


@Vbuy It depends on many variables. The jogger story might be false, but outdoors transmission can be very fast. Close contact, no wind, coughs and sneezes, and of course outdoor crowding.
It's not where we should emphasize the most important measures, but caution is due, bc this is by far the most transmissible airborne virus ever known. Just saying.

@xabitron1 A study in Ireland found that outdoor transmission accounted for 0.1% of all COVID cases nationally. As you say, probably not where we want to spend our advocacy efforts.

Here’s a twitter link in which an HVAC engineer (@joeyfox85) explains why a fleeting outdoor exposure is highly unlikely to transmit COVID


@xabitron1 @SARS2isAirborne OK, feel free to cite your own research study showing rates of outdoor transmission.

I’ve seen no empirical evidence to suggest that outdoors is where we should be focusing our advocacy efforts. It’s pretty clear that most transmission happens inside crowded unmasked spaces.

@Vbuy @xabitron1

We need to not be telling people who really can't afford to catch covid that they're safe outdoors. If you don't like this Chinese study then I can't really help you because China is the only country that's still in a position to do this sort of work.

@SARS2isAirborne @xabitron1 It’s not a matter of liking a study. I’m a scientist. I appraise research on the basis of scientific rigor. This one doesn’t even share the data on which the results and conclusions are based. And there are methodological flaws and missing information.

@Vbuy @xabitron1

What exactly is wrong with the paper that would materially change the conclusion? Their conclusion is the only one that makes sense based on the data presented. The only way I see that the paper is wrong is if they just made the whole thing up.

@SARS2isAirborne @xabitron1 There’s nothing wrong with the conclusion per se. But the study is flawed so it doesn’t support it. So it’s essentially an opinion, not an empirically based conclusion.

@Vbuy @SARS2isAirborne Indeed. It's not an empirically based conclusion, that for sure.
Maybe it's actually impossible to conduct any study of outdoor fleeting transmission in real life.
People can believe it occurred to them, but you never can proof that, unless it were possible sequential genomic following of infected. I don't think it's possible.

@OldYesButWise @Vbuy @SARS2isAirborne I think Dr Buysse is right. In settings outdoors when there isn't crowding, the risk is negligible indeed. Closeness regarding sars2 virus could mean certain risk. But I wouldn't be too concerned about that, but a bit of caution with a biohazard is always good.

@OldYesButWise @Vbuy @SARS2isAirborne The problem is that people take for granted that outdoors is utterly safe, and many have close contact for long, in conversations for instance, and end up transmitting it. Doing a selfie can mean contagion, for instance, a cough, and of course, a sneeze.
And we should be aware how much people actually cough and sneeze.

@Vbuy @xabitron1

The only reasonable critique I've seen is that the paper is a bit skimpy on the details of the sequencing and the actual sequences would have been nice. Neither if these things should actually affect the results. Everything else has boiled down to "I don't like the results so look at this problem I've invented".

@xabitron1 @SARS2isAirborne

We had this whole debate yesterday on Twitter and it was completely shut down after people began sharing their skepticism about the study and critiqued it. Not sure what else there is to say. The study methodology is questionable, there are no data to substantiate the results, which means no conclusions can be drawn.

If people want to raise concerns about outdoor transmission, that’s fine, but this study isn’t the best research to support that.

@Vbuy @SARS2isAirborne Yes. We must, after hammering home the need of measures in indoor spaces, raise concern about human to human transmission everywhere, even outdoors.
I, of course, trust you that the Chinese study is crappy.
But that doesn't entail that we have to only focus on indoor spaces. The main focus, yes! The only focus, no.

@Vbuy @SARS2isAirborne Can I go to clean the kitchen now, or do we have to start battling about this now 🤣

@Vbuy @SARS2isAirborne Yeah, I don't trust that study either.
Don't take my answers as confrontational. But I would be cautious even outdoors. For many of our behaviors there are not studies backing them.
Talking about outdoors transmission is not whimsical, it's precautionary principle because, even the risk being lower, it's higher than what would be recommended.

@Vbuy @SARS2isAirborne Yes, you are right, I don't have any research study. I would be cautious though. You can see it when it's foggy.

@Vbuy @SARS2isAirborne I think you are right that we should emphasize indoors measures. But recommending caution with sars2, even outdoors, shouldn't be taken as narrowing the scope.
I wouldn't recommend you going to a park where everybody is jogging to not wear a mask, for instance.
Do we need research studies for that, or it would suffice some common sense?

@SARS2isAirborne @xabitron1 Based on what we know about the transmission of respiratory viruses, parks and other places where people are spread out are low-risk. But crowded outdoor arenas or dining outdoors with others at a table increase the risk of transmission.

I would not mask up if a jogger ran by me in a park that was sparsely populated. This is a fleeting exposure, not a sustained close contact.

@Vbuy @SARS2isAirborne That's your personal take on the matter. Only one infection in that scenarion, among, say a million contagions, could mean dozens of infected people, in chains of transmission. During an airborne pandemic, chains of transmission can be very large. That we know. You don't need studies for that, do you?

@Vbuy @SARS2isAirborne I would be very careful though, the amount of aerosols coming from a jogger is very high. I they come too close, it takes one second to transmit it. With this virus there is not need of sustained close contact to transmit it. A jogger viral load expelled can be impressive. No wind, you are done.

@Vbuy @SARS2isAirborne The "sustained" hypothesis is still to be proven.
I would lean to the side of caution until proven wrong. I won't be, btw.

@SARS2isAirborne @xabitron1 Well, the aerosol experts place the risk of infection in this example to be quite low. Not zero, but low.

We face risks every time we wake up in the morning. The goal is to calculate those risks and mitigate accordingly. I worry more about the risks of driving my car on the highway than I do about passing someone on a path in a park, with wind flow and limited sustained contact in my favor.

@Vbuy @SARS2isAirborne Of course, but, please, keep having in the back of your mind that with this virus you are driving a road all the time there is people around.

@Vbuy I do not think your statement is correct. I have just read said raport. As far as I understand everything in it has been validated by checking the virus mutations of those infected.

On a sideline: Why o why should anyone trust the CDC on anything at this stage? They are lying openly!

@Vbuy how is it not plausible? Every variant has a more contagious. It’s airborne. Explain where the plausibility is missing.

@Cynde Please read the the thread that I attached from Twitter. It outlines the design flaws in this study, the lack of plausibility based on knowledge about airborne transmission outdoors, the lack of data on contact tracing to back up the results and conclusions, etc.

@Vbuy the study was done in China, that still does contact tracing. This updates the knowledge of airborne transmission outside. I read the study.

@Cynde “They successfully contact traced 20496 people in the park in a short period. You can believe this if you like.” -@joeyfox85

Plus the study provided no data. You can’t make an empirical claim without providing the data. Where’s the data?


Yes, I believe that China’s capacity and commitment to contact tracing is the only way this could have been accomplished.

@Cynde Then they need to link to the data used in the analysis. That’s the way publishing research results work.

@Vbuy I mean, I read the actual study and the data and most people will not read that kind of dense data. I don’t see what’s missing. Maybe you’re reading summaries and not the actual white paper.

@Vbuy what does surprise me though, is the anger underlying your responses. I’m immunocompromised and have been at home since March 2020 and I’m not as angry as you are. Can you explain?

@Vbuy I think it's important you raise this to the fore, that the study is flawed. Very flawed indeed.

@Vbuy Don't just cite sources because they're "plausible". Before you cite a source, check if it's reputable, i.e. from actual scientists with actual degrees, in a reputable journal, and preferably if the study is peer reviewed. Your first warning bell should NOT be that something is merely hard to believe.

Sign in to participate in the conversation

Everyone is welcome as long as you follow our code of conduct! Thank you. is maintained by Sujitech, LLC.