Hacker News Reader

Comment by nostromo | Hacker News Reader

This article speaks in a very authoritative tone, but the assertions aren't fully backed by the research it links to.

And it bothers me that the quote, "dramatically less likely" is not a quote from the linked research, but seemingly just a pull quote of the article itself.

I support people wearing masks, even if it turned out to only be marginally better than not wearing one, but this article is borderline overreaching.

View on HN

The linked article seems to back it up: https://link.springer.com/article/10.1007/s11606-020-06067-8

> In a more recent report from a different cruise ship outbreak, all passengers were issued surgical masks and all staff provided N95 masks after the initial case of COVID-19 on the ship was detected. In this closed setting with masking, where 128 of 217 passengers and staff eventually tested positive for SARS-CoV-2 via RT-PCR, the majority of infected patients on the ship (81%) remained asymptomatic, compared with 18% in the cruise ship outbreak without masking.

> A report from a pediatric hemodialysis unit in Indiana, where all patients and staff were masked, demonstrated that staff rapidly developed antibodies to SARS-CoV-2 after exposure to a single symptomatic patient with COVID-19. In the setting of masking, however, none of the new infections was symptomatic. And in a recent outbreak in a seafood processing plant in Oregon where all workers were issued masks each day at work, the rate of asymptomatic infection among the 124 infected was 95%. An outbreak in a Tyson chicken plant in Arkansas with masking also showed a 95% asymptomatic rate of infection.

It makes intuitive sense that a face covering would reduce the viral load one is exposed to. I've heard of other studies that have shown that the degree of virus exposure affects outcomes. Those involved exposure time and exposure distance to symptomatic patients with COVID-19. If a face covering reduces the viral load you get exposed to, seems like it would have the same effect as getting a lower dose exposure due to being a greater distance away or because of a reduced exposure time with a contagious individual. I hope more research supports the benefits of masks as it sounds like good news.

The viral load thing came up in some podcast I was listening too. So experiments were done with the flu Or cold virus and a smaller load resulted in a less severe infection.

They obviously can’t repeat the experiment with COVID. They suspect the same thing happens but they aren’t sure.

Oh the off chance it really is true, I’m wearing a mask!

would be great if someone can find them, but pretty sure there was a study done during the SARS 1 outbreak in the Canadian hospital that attempted to demonstrate that physical proximity to severe cases (and highly symptomatic individuals?) was correlated to viral load and further correlated to severity of illness. At least I saw people early on in Novel Coronavirus days of Jan/Feb speculating about the meaning of said study.

> It makes intuitive sense that a face covering would reduce the viral load one is exposed to.

I've been astounded and dismayed by people's ability to reason themselves out of this obvious conclusion.

How similar were the strains on the two cruise ships?

That cruise ship didn't issue masks until after the outbreak had occurred: "The first recorded fever on board the ship was a febrile passenger on day 8. Isolation protocols were immediately commenced, with all passengers confined to cabins and surgical masks issued to all. Full personal protective equipment was used for any contact with any febrile patients, and N95 masks were worn for any contact with passengers in their cabins. The crew still performed duties, including meal services to the cabin doors three times a day, but rooms were not serviced. Expedition staff helped with crew duties at meal service."

So passengers were already infected when that 81% figure was computed.

https://thorax.bmj.com/content/75/8/693

In a village in Tuscany, over 3000 people were actively tested and 50-75% were asymptomatic: https://www.bmj.com/content/368/bmj.m1165

And among NYC labor and delivery patients, 88 percent were asymptomatic: https://www.washingtonpost.com/outlook/2020/04/20/we-tested-...

This number is not at all unusual in the general population, regardless of mask wearing.

The comments on the WaPo article are very high quality but show that we have no idea what's going on because the reporting of scientific data is uselessly vague in the critical details.

That doesn’t really support the idea that they protect the wearer, though, does it? They’re both cases where everyone was masked.

I think the hypothesis could be correct, but as presented, those observations are very poor data. For example, we would want to see if these few examples generalize to other cases, or are they just outliers.

It compares the Diamond Princess outbreak, which occurred in the hot spot temperature range (40s-50s F, mid-humidity), to a cruise around the Antarctic peninsula, which looks like it was about 20 degrees below the hot spot range and way outside the humidity range.

While there's no single slam-dunk study yet proving this with SARS-Cov-2 (Covid-19), there's so much mutually-reinforcing suggestive evidence that the authoritative tone of this UCSF professor/researcher/doctor seems justified, to me. In particular, there's a lot of evidence from other similar respiratory viruses.

Now also, there are patterns observed in masked-vs-unmasked Covid-19-hotspots for which the idea "masks cut initial infectious dose enough to make infections milder or totally asymptomatic" fits really well.

You can watch Dr. Gandhi presenting on this topic with slides & multiple paper/incident references, during a UCSF 'Grand Rounds' a few weeks ago - here's a direct link to where her talk starts:

https://youtu.be/Cio3rh6ta3w?t=1740

> but the assertions aren't fully backed by the researched it links to.

To say the least...

The article links to https://jamanetwork.com/journals/jama/fullarticle/2768396 to support, "Most infectious disease researchers and epidemiologists believe that the coronavirus is mostly spread by airborne droplets".

However, the linked study concludes, " All told, current understanding about SARS-CoV-2 transmission is still limited. There are no perfect experimental data proving or disproving droplet vs aerosol-based transmission of SARS-CoV-2."

That's not the conclusion, and cherry-picking those sentences is misleading because makes it sound like the article is citing a totally inconclusive paper. The next sentence is "The balance of evidence, however, seems inconsistent with aerosol-based transmission of SARS-CoV-2 particularly in well-ventilated spaces."

That "particularly in well-ventilated spaces" is doing a lot of work.

In normal times, people spend a lot of time with other people in not-very-well-ventilated spaces - including, unfortunately, many conference-rooms, classrooms, small shops, bars/nightclubs, etc.

So in all those actual places, Covid-19 is aerosol-transmissible.

Also, in just the few weeks since that JAMA discussion, more actual examples of Covid-19 almost certainly transmitted by aerosols have been compiled; see for instance study/stories linked at:

https://twitter.com/EricTopol/status/1293276767042416640

I didn't use the word "conclusion". The article does conclude with the sentence I quoted as well as what you quoted. If you honestly read what I wrote, you would see that what I wrote is in the linked page, as is what you wrote, and the sentence from each of our posts is orthogonal to the support that was being sought for the article.

I was not restating the conclusion, but showing how the original article was quoting support from a place that did not support what was being said.

That is a weird wording on the last sentence, because the virus doesn’t transmit by magic. All epidemiologists I’ve read sofar seem to speak of mostly droplet transmission with some role for aerosols, which is indeed still studied afaik.

there is a growing number of those that believe the virus also transmits airborne. droplet != airborne.

Any good links for that? I haven’t seen anything beyond speculation that suggests that, and the patterns of infection in places I’m aware of aren’t consistent with airborne.

https://www.nytimes.com/2020/08/11/health/coronavirus-aeroso...

Aerosols are basically floating particles with virus, which is not airborne, but still carries the virus a lot further.

I agree. That is why the article for this post is so odd. It links to many pages that do not support what is being stated. It's almost as if they chose 100 random places to link, possibly from only looking at the first hits on google searches.

Reply on news.ycombinator.com