Analysis: Misleading claims about Pfizer/BioNTech vaccine safety for pregnancy

Annie Lab looks into the supposed ‘evidence’ mentioned in a tweet that claims the safety of Pfizer/BioNTech vaccine was determined based on lab tests on pregnant rats, not humans.

A tweet on June 8 suggested that Pfizer’s COVID-19 vaccine is not safe for pregnant women despite what the pharmaceutical company says.

It claimed the vaccine was tested on 42 rats in a lab and not humans, and half of the rodents produced babies with birth defects.

It went on to claim that “90% of vaccinated pregnant women lost their babies” as well.

The tweet was posted by Pearson Sharp who has over 28,000 followers. He describes himself as a host of One America News in the profile with a link to his YouTube channel.

The tweet in question has gained 1,172 likes and 946 retweets at the time of writing.

Annie Lab looked into the claims and supposed “evidence” mentioned by Sharp in the same tweet. We found all of them misleading and lacking context.

Pfizer-funded study on rats

The tweet links to a research article about the Pfizer-funded fertility and developmental toxicity study of the COVID-19 vaccine on rats.

This research was completed in December 2020 and, contrary to what Sharp claims, found no causal association between vaccination and birth defects in rats.

Although a higher occurrence of supernumerary lumbar ribs, or the condition of having additional ribs, and other anomalies and variations were observed, such findings from the fetal visceral and skeletal examinations were found to be incidental.

Historical records show Wistar Hannover rats, the subject species used for the toxicity study, have a higher incidence of spontaneous variations than other common lab rat species, the article noted.

Also analyzing the data from the control group (rats with no vaccination), the research found no apparent adverse effects of the vaccine.

Testing on animals before clinical trials is a regular process in the development of new medical products, including vaccines, to assess the possible health effects.

The World Health Organization (WHO) recommended Comirnaty, the product name for the Pfizer/BioNTech COVID-19 vaccine, to pregnant individuals and advised “against delaying or terminating” pregnancy for vaccination on Jan. 12, 2021.

Safety of vaccine for pregnant individuals

The WHO’s latest guideline updated on June 10, 2022, maintains the same recommendation.

It says the real-world data supports “a favorable safety profile” of Comirnaty for pregnant individuals and mentions the risk of having adverse consequences of COVID-19 disease during pregnancy.

The Centers for Disease Control and Prevention (CDC) in the United States also recommends pregnant persons to be vaccinated and suggests Comirnaty over Johnson & Johnson for primary and booster injection.

A CDC analysis in 2021 did not find an increased risk of miscarriage among nearly 2,500 pregnant individuals who received an mRNA COVID-19 vaccine.

According to the CDC, miscarriage typically occurs in about 11-16% of pregnancies, and this study found miscarriage rates after receiving a COVID-19 vaccine were around 13%, “similar to the expected rate of miscarriage in the general population.”

The tweet in question did not provide any particular source for the claim that 90% of the women who had Pfizer’s vaccine “lost their babies” but investigations into similar claims have been conducted by many fact-checking organizations around the world including Full Fact, USA Today, and Reuters.

They all found such claims misleading or groundless.

“Official document” mentioning the study on rats

The other “evidence” attached to the tweet is a screenshot of a document that discusses the study on rats.

Annie Lab found that it is a part of a document called Delegate’s Overview and Request for Advisory Committee on Vaccines’ (ACV) Advice published in Australia on Jan. 11, 2021.

It was prepared by Australia’s Therapeutic Goods Administration (TGA), the body mandated under the country’s Department of Health to regulate vaccines and other medicines, for ACV.

The ACV is an independent body that advises on the safety, quality and efficacy of vaccines supplied in Australia, comprising medical specialists.

Timeline of Comirnaty provisional approval in Australia (made by Annie Lab)

The screenshot shows a part of the TGA evaluation of Comirnaty in 2021 as Pfizer applied for provisional approval that would enable the public’s immediate and early access to the vaccine then.

As opposed to Sharp’s claim, however, this document also concluded that “studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.”

Furthermore, the attached screenshot was an earlier version of TGA’s evaluation.

According to the following meeting minutes, the committee proposed that with additional information obtained from Pfizer, the vaccine should be classified in a safer category, and the language was subsequently changed to “studies in animals have not shown evidence of an increased occurrence of fetal damage.”

Nonclinical Evaluation Report showing the edits on “Use in pregnancy” section.

The earlier version of the document, shown in the tweet’s screenshot, does not reflect the final decision by the health authority in Australia.

The country’s Department of Health currently says the Pfizer vaccine is safe for pregnant individuals at any stage of pregnancy and individuals planning on becoming pregnant.

They also recommend getting all three doses, based on “real world evidence.”