Mexico City ivermectin updates

Imagen TV screenshot

We posted our decision to withdraw the paper, “Ivermectin and the odds of hospitalization due to COVID-19″, here. Since then there have been new developments. I will update this page if needed. -Philip Cohen

As of February 5.


  • The lead author on the paper, José Merino, tweeted a link to a letter to me over the names of six of the original seven authors. The letter called the decision to withdraw their paper “unethical, colonialist, and authoritarian,” and demanded my resignation. You can read the statement here.
  • The Secretaría de Salud de la Ciudad de México posted a statement (in Spanish; English translation here), arguing that the use of ivermectin to treat COVID-19 was “supported by the scientific evidence available worldwide in 2020,” before the availability of vaccines, due its documented effectiveness, low cost, and lack of harmful effects. Distributing the medicine was not an experiment, they wrote. In addition, about SocArXiv, they wrote: “This study was kept on the SocArxiv portal for almost a year, it always had code and data available for replication, and its conclusions are very similar to other works (Ascencio-Montiel et al. 2022).” (Note, that study, which used the same data from the Mexico City COVID-19 health kit distribution, acknowledged that the kids “included, besides an information brochure and a pulse oxymeter, medications such as azithromycin, ivermecin, acetaminophen and aspirin” — and the study made no claims about the effects of ivermectin itself, and the data doesn’t indicate who took which medicines.)



On withdrawing “Ivermectin and the odds of hospitalization due to COVID-19,” by Merino et al

On withdrawing “Ivermectin and the odds of hospitalization due to COVID-19,” by Merino et al.

4 February 2022

Preamble by Philip N. Cohen, director of SocArXiv

SocArXiv’s steering committee has decided to withdraw the paper, “Ivermectin and the odds of hospitalization due to COVID-19: evidence from a quasi-experimental analysis based on a public intervention in Mexico City,” by Jose Merino, Victor Hugo Borja, Oliva Lopez, José Alfredo Ochoa, Eduardo Clark, Lila Petersen, and Saul Caballero. [10.31235/]

The paper is a report on a program in Mexico City that gave people medical kits when they tested positive for COVID-19, containing, among other things, ivermectin tablets. The conclusion of the paper is, “The study supports ivermectin-based interventions to assuage the effects of the COVID-19 pandemic on the health system.”

The lead author of the paper, José Merino, head of the Digital Agency for Public Innovation (DAPI), a government agency in Mexico City, tweeted about the paper: “Es una GRAN noticia poder validar una política pública que permitió reducir impactos en salud por covid19” (translation: “It is GREAT news to be able to validate a public policy that allowed reducing health impacts from covid19”). The other authors are officials at the Mexican Social Security Institute and the Mexico City Ministry of Health, and employees at the DAPI.

We have written about this paper previously. We wrote, in part:

“Depending on which critique you prefer, the paper is either very poor quality or else deliberately false and misleading. PolitiFact debunked it here, partly based on this factcheck in Portuguese. We do not believe it provides reliable or useful information, and we are disappointed that it has been very popular (downloaded almost 10,000 times so far). … We do not have a policy to remove papers like this from our service, which meet submission criteria when we post them but turn out to be harmful. However, we could develop one, such as a petition process or some other review trigger. This is an open discussion.”

The paper has now been downloaded more than 11,000 times, among our most-read papers of the past year. Since we posted that statement, the paper has received more attention. In particular, an article in Animal Politico in Mexico reported that the government of Mexico City has spent hundreds of thousands of dollars on ivermectin, which it still distributes (as of January 2022) to people who test positive for COVID-19. In response, University of California-San Diego sociology professor Juan Pablo Pardo-Guerra posted an appeal to SocArXiv asking us to remove the “deeply problematic and unethical” paper and ban its authors from our platform. The appeal, in a widely shared Twitter thread, argued that the authors, through their agency dispensing the medication, unethically recruited experimental subjects, apparently without informed consent, and thus the study is an unethical study; they did not declare a conflict of interest, although they are employees of agencies that carried out the policy. The thread was shared or liked by thousands of people. The article and response to the article prompted us to revisit this paper. On February 1, I promised to bring the issue to our Steering Committee for further discussion.

I am not a medical researcher, although I am a social scientist reasonably well-versed in public health research. I won’t provide a scholarly review of research on ivermectin. However, it is clear from the record of authoritative statements by global and national public health agencies that, at present, ivermectin should not be used as a treatment or preventative for COVID-19 outside of carefully controlled clinical studies, which this clearly was not. These are some of those statements, reflecting current guidance as of 3 February 2022.

  • World Health Organization: “We recommend not to use ivermectin, except in the context of a clinical trial.”
  • US Centers for Disease Control and Prevention: “ivermectin has not been proven as a way to prevent or treat COVID-19.”
  • US National Institutes of Health: “There is insufficient evidence for the COVID-19 Treatment Guidelines Panel (the Panel) to recommend either for or against the use of ivermectin for the treatment of COVID-19.”
  • European Medicines Agency: “use of ivermectin for prevention or treatment of COVID-19 cannot currently be recommended outside controlled clinical trials.”
  • US Food and Drug Administration: “The FDA has not authorized or approved ivermectin for use in preventing or treating COVID-19 in humans or animals. … Currently available data do not show ivermectin is effective against COVID-19.”

For reference,  the scientific flaws in the paper are enumerated  at the links above from PolitiFact, partly based on this factcheck from Estado in Portuguese, which included expert consultation. I also found this thread from Omar Yaxmehen Bello-Chavolla useful.

In light of this review, a program to publicly distribute ivermectin to people infected with COVID-19, outside of a controlled study, seems unethical. The paper is part of such a program, and currently serves as part of its justification.

To summarize, there remains insufficient evidence that ivermectin is effective in treating COVID-19; the study is of minimal scientific value at best; the paper is part of an unethical program by the government of Mexico City to dispense hundreds of thousands of doses of an inappropriate medication to people who were sick with COVID-19, which possibly continues to the present; the authors of the paper have promoted it as evidence that their medical intervention is effective. This review is intended to help the SocArXiv Steering Committee reach a decision on the request to remove the paper (we set aside the question of banning the authors from future submissions, which is reserved for people who repeatedly violate our rules). The statement below followed from this review.

SocArXiv Steering Committee statement on withdrawing the paper by Merino et al. (10.31235/

This is the first time we have used our prerogative as service administrators to withdraw a paper from SocArXiv. Although we reject many papers, according to our moderation policy, we don’t have a policy for unilaterally withdrawing papers after they have been posted. We don’t want to make policy around a single case, but we do want to respond to this situation.

We are withdrawing the paper, and replacing it with a “tombstone” that includes the paper’s metadata. We are doing this to prevent the paper from causing additional harm, and taking this incident as an impetus to develop a more comprehensive policy for future situations. The metadata will serve as a reference for people who follow citations to the paper to our site.

Our grounds for this decision are several:

  1. The paper is spreading misinformation, promoting an unproved medical treatment in the midst of a global pandemic.
  2. The paper is part of, and justification for, a government program that unethically dispenses (or did dispense) unproven medication apparently without proper consent or appropriate ethical protections according to the standards of human subjects research.
  3. The paper is medical research – purporting to study the effects of a medication on a disease outcome – and is not properly within the subject scope of SocArXiv.
  4. The authors did not properly disclose their conflicts of interest.

We appreciate that of the thousands of papers we have accepted and now host on our platform, there may be others that have serious flaws as well.

We are taking this unprecedented action because this particular bad paper appears to be more important, and therefore potentially more harmful, than other flawed work. In administering SocArXiv, we generally err on the side of inclusivity, and do not provide peer review or substantive vetting of the papers we host. Taking such an approach suits us philosophically, and also practically, since we don’t have staff to review every paper fully. But this approach comes with the responsibility to respond when something truly harmful gets through. In light of demonstrable harms like those associated with this paper, and in response to a community groundswell beseeching us to act, we are withdrawing this paper.

We reiterate that our moderation process does not involve peer review, or substantive evaluation, of the research papers that we host. Our moderation policy confirms only that papers are (1) scholarly, (2) in research areas that we support, (3) are plausibly categorized, (4) are correctly attributed, (5) are in languages that we moderate, and (6) are in text-searchable formats. Posting a paper on SocArXiv is not in itself an indication of good quality – but it is often a sign that researchers are acting in good faith and practicing open scholarship for the public good. We urge readers to consider this incident in the context of the greater good that open science and preprints in general, and our service in particular, do for researchers and the communities they serve.

We welcome comments and suggestions from readers, researchers, and the public. Feel free to email us at, or contact us on our social media accounts at Twitter or Facebook.

SocArXiv policy on withdrawing papers

The Center for Open Science has added withdrawal functionality to its preprint service platform. We are glad to have this capacity, but we will not be permitting the withdrawal of papers in routine cases. Withdrawing is a convenient option if an author makes an error in the submission process, for example accidentally submitting the wrong version; if a paper has not yet been approved, we are happy to accommodate such requests. However, if a paper has already been accepted, and thus entered the scholarly record, we will follow the policy below.

Unfortunately, authors now see a large “Withdraw Paper” button on the page where they edit their paper entries. We are working with COS to change how this option is presented to authors, and also to make users aware of our policy. Posting a paper on SocArXiv is easy, which brings great benefit to the thousands of people who have shared their work. However, authors should be aware that posting papers is generally nonreversible. We offer this policy and its explanation to help further this understanding.

Dog leaping fearlessly off a dock into water
Photo by Emery Way

SocArXiv Withdrawal Policy

May 25, 2019

In case of revision, the current version will be found here.

The Center for Open Science (COS), which hosts SocArXiv, has enabled the withdrawal of papers from its paper services. Authors who wish to withdraw their papers may request a withdrawal from the SocArXiv moderators, according to the terms of this policy.

Permission for withdrawal will only be granted in the very rare circumstance in which we have a legal obligation to remove a paper, such as if it contains private personal information or it is subject to a substantiated copyright claim. In cases where a paper is withdrawn, it will be replaced by a “tombstone” page (here is an example), which includes the original paper’s metadata (author, title, abstract, DOI, etc.), and the reason for withdrawal. After that point, the paper will be locked to further modification.

Papers that infringe on copyrights will be removed in accordance with the Digital Millennium Copyright Act, under the Center for Open Science terms of use, available here.

If authors wish to withdraw papers for other reasons — for example, if they are not confident of the findings or otherwise no longer endorse the paper — they should post a new “version” of the paper that is a single page announcing the withdrawal. They may, for example, request that readers do not further cite, use, or distribute previous versions (which will remain available under the list of previous versions). Instructions on how to post a new version are available here; we are happy to help authors do this.

This policy is very similar to the retraction of an article by an academic journal, which only rarely involves removal of access to the original paper, instead generally relying on a notification of retraction in its place.

Instructions for request a withdrawal are available here:

Why doesn’t SocArXiv let authors decide when to withdraw a paper?

Papers on SocArXiv are part of the scholarly record. Upon being posted, they are given a Digital Object Identifier (DOIs), and a persistent URL from COS. The link is automatically tweeted by our announcement account, and the system also generates a citation reference. The document is immediately citable and retrievable by human or machine agents. In short, posting a paper on SocArXiv is a research event that cannot be undone by deleting the document. Preserving the scholarly record is our obligation to the scholarly community.

Authors who post papers on SocArXiv are notified, at the final point of submission, that they will be “unable to delete the preprint file, but [they] can update or modify it.” Authors also are required to confirm that all contributors have agreed to share the paper, and that they have the right to share it. (All co-authors have the same rights to distribute a copyrighted work, unless a subsequent agreement has intervened, so an objection to the posting by a co-author is not the basis for removal.)

The Internet has made it possible to distribute work without relinquishing the original digital file, which makes it possible to delete the version readers access — a privilege that was not available when research was distributed in printed form. However, the Internet has also made it difficult or impossible to remove all traces or copies of a digital document. This is a challenging environment for authors.

We are sympathetic to the desire of some authors to remove copies of their earlier work from circulation, for a variety of reasons, and we appreciate that our policy may cause frustration. We hope authors will carefully consider it before they post their work.

Our policy is very similar to that employed by the older and more established preprint servers, arxiv and bioRxiv.

bioRxiv’s FAQ page reads:

Can I remove an article that has already posted on bioRxiv?

No. Manuscripts posted on bioRxiv receive DOI’s and thus are citable and part of the scientific record. They are indexed by services such as Google Scholar, Microsoft Academic Search, and Crossref, creating a permanent digital presence independent of bioRxiv records. Consequently, bioRxiv’s policy is that papers cannot be removed. Authors may, however, have their article marked as “Withdrawn” if they no longer stand by their findings/conclusions or acknowledge fundamental errors in the article. In these cases, a statement explaining the reason for the withdrawal is posted on the bioRxiv article page to which the DOI defaults; the original article is still accessible via the article history tab. In extremely rare, exceptional cases, papers are removed for legal reasons.

At this writing, just 32 out of 50,401 preprints on bioRxiv have been withdrawn, a rate of 6 per 10,000.

On arXiv, the instructions read:

Articles that have been announced and made public cannot be completely removed. A withdrawal creates a new version of the paper marked as withdrawn. That new version displays the reason for the withdrawal and does not link directly to the full text. Previous versions will still be accessible, including the full text.

On the other hand, at least one paper service, Elsevier’s SSRN (formerly the Social Science Research Network), allows authors to delete their papers from their repository immediately for any reason (FAQ). Similarly, some authors choose to distribute their work on their own websites, where they have more complete control over the contents. We believe these approaches put the needs of the author of over those of the research community. While a reasonable choice in some cases, this represents a philosophy different from ours.

We want an open, equitable, inclusive scholarly ecosystem in which people are free to share and use information as freely as possible. We have created this policy to serve that goal.