CLAIM: The head of research at Pfizer says the COVID-19 vaccine causes female sterilization because it contains a spike protein known as syncytin-1.
THE FACTS: The Pfizer and BioNTech COVID-19 vaccine does not contain the protein syncytin-1, which is important for the creation of placenta.
The head of research at Pfizer made no such claim. Social media users are sharing a screenshot from an article titled “Head of Pfizer Research: Covid Vaccine is Female Sterilization” to claim the vaccine results in sterilization of women. Information in the article, carried by the blog “Health and Money News,” is attributed to Michael Yeadon, a retired British doctor who left Pfizer nine years ago. The article says “the vaccine contains a spike protein called syncytin-1, vital for the formation of human placenta in women.” It goes on to say “the vaccine works so that we form an immune response AGAINST the spike protein, we are also training the female body to attack syncytin-1, which could lead to infertility in women of an unspecified duration.”
Posts carrying the false information shared a petition filed by Yeadon and Wolfgang Wodarg, a German physician, to the European Medicines Agency that demanded that clinical trials of the Pfizer vaccine be stopped in the European Union until more safety and efficacy data can be provided. In the petition, the two acknowledge that there is no indication “whether antibodies against spike proteins of SARS viruses would also act like anti-Syncytin-1 antibodies.” But they go on to say “if this were to be the case this would then also prevent the formation of a placenta which would result in vaccinated women essentially becoming infertile,” the petition says. Yeadon said he is not saying there is a guaranteed problem between the vaccine and fertility, but asked if the vaccine makers would be sure there would not be a problem.
Pfizer spokeswoman Jerica Pitts confirmed to The Associated Press that their vaccine candidate has not been found to cause infertility. “It has been incorrectly suggested that COVID-19 vaccines will cause infertility because of a shared amino acid sequence in the spike protein of SARS-CoV-2 and a placental protein,” she said in an email. “The sequence, however, is too short to plausibly give rise to autoimmunity.” Experts also say there is no evidence that the Pfizer vaccine would result in sterilization of women. Rebecca Dutch, chair of University of Kentucky’s department of molecular and cellular biochemistry, said in an email that while syncytin-1 and the spike protein broadly share some features, they are quite different in the details that antibodies recognize. Aside from the fact that COVID-19’s spike protein and syncytin-1 are viral fusion proteins that cause membrane fusion, they are not related at all, Dutch said.
Additionally, the vaccine being developed by Moderna, like the one being developed by Pfizer and BioNTech, relies on messenger mRNA, which tells the body how to make the spike protein and trains the immune system to identify the real virus. They do not contain syncytin-1.
—Associated Press writer Beatrice Dupuy in New York contributed this report.