How Social Media Posts Twisted the Conclusions of a Vaccine Safety Study

Scientists take vaccine safety very seriously. Even after a vaccine has entered the market, vaccine safety monitoring systems are in place to identify any rare side effects that may not have shown up in clinical trials.

Most recently, a study of more than 99 million vaccinated people around the world, conducted by the Global Vaccine Data Network, reported its conclusions on COVID-19 vaccine safety.

The study largely confirmed the known, rare side effects that already have been identified via researchers’ scrutiny, Staff Writer Kate Yandell explains in a new story.

The study also found a possible new safety signal for a very rare problem that the authors said needed to be investigated further. The study means that “early warning systems are solid,” said Marc Veldhoen, an immunologist at the Instituto de Medicina Molecular João Lobo Antunes in Portugal, in a post on X, formerly known as Twitter.

But as has happened before, a flurry of social media posts managed to twist scientists’ efforts to evaluate vaccine safety into fodder for anti-vaccine narratives.

Some posts left out the fact that the adverse events identified are rare, that they had largely already been identified via other systems and that the vaccines have proven benefits. Others made unfounded claims that people should not have received the vaccines or that the risks of vaccination outweigh the benefits.

In fact, the study confirmed the Moderna and Pfizer/BioNTech vaccines come with a rare risk of myocarditis and pericarditis, conditions characterized by inflammation of the heart muscle and lining. It also confirmed rare blood clotting and neurological side effects that have been reported with the AstraZeneca vaccine — which uses similar technology to the Johnson & Johnson vaccine that was linked to the same side effects in the U.S. 

For the Moderna and AstraZeneca vaccines, the researchers found a possible association between the first dose and a rare autoimmune neurological condition. If the new association is causal — which has not been established — it would translate to 1 case per 1.75 million people vaccinated, study co-author Anders Hviid, head of the department of epidemiology research at the Statens Serum Institut in Denmark, told Kate in an email. 

For more about the study and how it was misrepresented, read “Study Largely Confirms Known, Rare COVID-19 Vaccine Side Effects.”

Reader: Approximately how many people have entered the US illegally in the past 4 years, and from what countries?

FactCheck.org Managing Editor Lori Robertson: We published a story this week that's related to your question: "Breaking Down the Immigration Figures."

In that story,  we wrote:
 
"Encounters on the southern border of those trying to enter the U.S. without authorization have gone up significantly under President Joe Biden. Government statistics show that in the initial processing of millions of encounters, 2.5 million people have been released into the U.S. and 2.8 million have been removed or expelled."

We cautioned that these are the initial dispositions – people who are released have notices to appear in immigration court or notices to report to Immigration and Customs Enforcement. Some have parole, which are specific programs that permit temporary residence in the U.S. In other words, what ultimately happens to those released into the U.S. isn't yet known. Immigration cases can take years to work their way through court backlogs. 

There are a lot more statistics and information in our story. The data come from the Department of Homeland Security on this webpage.

We didn't provide a breakdown for the 2.5 million releases by all countries, but you can see that data in the DHS spreadsheet titled CBP SW Border Encounter Book-Out Outcomes by Selected Citizenship. It shows that the releases include people from Mexico, Venezuela, Guatemala, Honduras, Colombia, Cuba, Ecuador, Nicaragua, Haiti, Peru and "other." A footnote says that the named countries are the top 10 citizenships of encounters at the border for the period December 2022-November 2023.

Wrapping Up

Here's what else we've got for you this week:

• "Posts Mislead About COVID-19 Vaccine Safety With Out-of-Context Clip of FDA Official": Given the extra scrutiny and large number of doses, reports of possible side effects to a vaccine safety monitoring system increased with the COVID-19 vaccines. The high number of reports does not mean the vaccines are unsafe, contrary to suggestions made by posts sharing a clip of a Food and Drug Administration official acknowledging the surge.=  
• "Posts Misrepresent Rescue of Crew from Ship Attacked by Houthis": A missile fired by Yemen’s Houthi militants damaged a British-owned cargo ship on the Red Sea on Feb. 18 and forced its crew to evacuate. Some social media posts falsely claimed the Houthis “made sure to rescue” the 24-member crew. U.S. Central Command said the crew was rescued by a “coalition warship along with another merchant vessel.”
• "Posts Use Bogus Document to Falsely Claim Zelenskyy Plans Move to Florida": President Volodymyr Zelenskyy has traveled throughout the world seeking support for Ukraine’s effort to resist Russia’s invasion, but he has always returned to his war-torn country. Some social media posts — showing a fake naturalization document — falsely claim preparations are underway to bring him to the United States.

• "Publicaciones utilizan un video descontextualizado de un funcionario de la FDA para engañar sobre la seguridad de las vacunas contra el COVID-19": Dado el intenso escrutinio y el gran número de dosis administradas, los informes de posibles efectos secundarios presentados al sistema de control de seguridad de las vacunas aumentaron con las vacunas contra el COVID-19. El elevado número de informes no significa que las vacunas sean inseguras, contrariamente a lo que sugieren publicaciones que comparten un video de un funcionario directivo de la FDA admitiendo el aumento.