In recent weeks, an allegedly peer-reviewed study from Stanford University exposing the dangers of facemasks has gained popularity online.
The paper may not have been peer-reviewed (in the conventional sense, at least) nor is it from Stanford University. It is published in a journal of dubious quality and makes various incorrect claims.
Face masks have been shown to reduce viral transmission. They are safe to wear. Under current rules you must wear a face mask in various public locations in the UK unless you are exempt or have a reasonable excuse.
The author
The paper titled “Facemasks in the COVID-19 era: A health hypothesis” was written by sole author Baruch Vainshelboim who is described as working in the cardiology division of the Veterans Affairs Palo Alto Health Care System (VAPAHCS) in California.
VAPAHCS describes itself as having close ties to Stanford University, and does have its own research operations.
The Associated Press has reported that both VAPAHCS and Stanford University have said that Dr Vainshelboim is not employed by them. Stanford University has confirmed this as well as saying it strongly supports the use of face masks.
The journal
The paper was published in the January edition of Medical Hypotheses, a journal which describes itself as “opening the field to radical hypotheses which would be rejected by most conventional journals”.
In the past, such radical hypotheses have included theories linking the wearing of high heels to schizophrenia, and suggesting masturbation for the treatment of nasal congestion in men.
A previous editor wrote in 2008: “The journal’s official stance is that more harm is done by a failure to publish one idea that might have been true, than by publishing a dozen ideas that turn out to be false.”
This suggests that theories in the journal should, at the very least, be taken with a pinch of salt.
Claims that the journal is peer-reviewed are misleading.
Peer review is a form of quality control whereby independent experts assess the methods, results and conclusions made by a forthcoming scientific paper, prior to publication.
In an interview in 2010, the current editor of Medical Hypotheses said that the journal would not use “classical peer review”.
Full Fact approached the journal’s editor for more detail on how this particular paper was reviewed who told us: “We are aware [of] all the issues related to the publication in question. Actions are in progress we will inform you as soon as final actions are complete.”
The paper itself
The paper makes many claims about Covid-19 and masks. We don’t aim to fact check them all but there are clear errors which cast doubt on the paper as a whole.
The paper misrepresents other papers examining the link between mask wearing and viral transmission.
One trial is claimed by the paper to have shown “no difference between wearing and not wearing facemask [sic] for coronavirus droplets transmission of particles of >5 µm.” (A µm is a micrometre, or one millionth of a metre).
This is false.
The trial looked at whether viral RNA was detectable in exhaled breath from 111 people infected with influenza, coronaviruses (though not SARS-CoV-2 which causes Covid-19) and rhinoviruses, depending on whether they were wearing a surgical mask or not.
It found that no droplets containing coronaviruses were detectable in breath exhaled from people wearing masks while coronavirus droplets were detected in 30% of people who weren’t wearing masks.
In a small study, this difference was not statistically significant, but that doesn’t make it evidence that masks have no effect.
Besides, masks did significantly reduce the number of aerosol particles containing coronavirus (aerosol particles being smaller than droplets). Coronavirus aerosol particles were not detectable in any of the participants wearing masks compared to 40% of those who were not wearing masks.
The Vainshelboim paper goes on to describe a meta-analysis (combining the results of several different scientific studies) which allegedly “found that compared to no masks, surgical mask and N95 respirators were not effective against transmission of viral infections or influenza-like illness.”
This is false. The meta-analysis cited didn’t look at whether masks were more effective compared to wearing no masks at all. It looked at whether surgical masks were less effective than N95 respirators (a different kind of mask).
In none of the six studies included in the meta-analysis were any of the participants told to not wear a mask, so it would have been impossible to measure the difference claimed.
The Vainshelboim paper also warns that wearing a surgical mask could harmfully raise carbon dioxide levels and lower oxygen levels in the blood.
Paul Hunter, Professor in Medicine at the University of East Anglia, conducted a review of the evidence on mask-wearing in April 2020. Last year he told Full Fact: “We spent some time looking for evidence of harm.”
“There are studies that show, with an N95 mask, some people have an elevated blood carbon dioxide level, and some also reduced oxygen level, so there is an element in truth in that. That does not apply to ordinary surgical masks, and it sure as heck doesn’t apply to other types of face covering.”
The paper also makes basic errors about epidemiology and the pandemic itself.
It muddles the “case fatality rate” (proportion of detected cases which are fatal) with the “infection fatality rate” (proportion of all infections, including undetected cases, which are fatal).
Despite using the wrong term, it also appears to claim that Covid has an “[infection] fatality rate of approximately 0.1%”. This would mean that 0.1% of people who catch Covid die from it.
This is easy to disprove, because many countries have sadly already lost more than 0.1% of their entire populations to Covid. In the case of the UK, it is 0.19% of the population.
We have approached the author for comment on these points and, at the time of publication, he has not responded.