Skip to content

Correcting this week’s misinformation: week of December 7, 2023

Are COVID vaccines related to miscarriage?

The Claim:

During a hearing proctored by Rep. Marjorie Taylor Greene, a Florida OB-GYN claims that COVID vaccines are related to miscarriage, highlighting the increase in miscarriages in her office since 2021.

The Facts:

The testimony acknowledges a limited number of patients, saying they deliver between 20-25 patients. Compare that to this systematic review and meta-analysis which included 149, 685 women, which found no increased risk of miscarriage and had comparable rates for ongoing pregnancy or live birth.

Additionally, while the OBGYN mentions the overall vaccination rate of the clinic, she does not mention confounding factors, such as her patients’ previous vaccine history, COVID status, changes in patient demographics, or other variables that could influence miscarriage rates.

Conversely, some studies suggest that COVID infection itself in early pregnancy can cause miscarriage.

Is DNA hidden in vaccines causing cancer?

The Claim:

A conspiracy theorist posits that COVID vaccines contain “500 times the DNA molecules” allowed by regulators, and goes on to connect this DNA to cancer.

The Facts:

SV40 is a simian virus that is most commonly found in the kidneys of several kinds of monkeys. It can also sometimes infect humans and can potentially cause cancer via tumor (T) antigens. Unfortunately, early batches of the polio vaccine became contaminated with SV40, and the methods used to inactivate the poliovirus did not reliably inactivate SV40. Importantly, epidemiological studies have found no increased cancer risk in those who received these vaccines.

Since then, a promoter gene (a DNA sequence that starts RNA transcription) of SV40 has been found to promote a high level of gene expression for producing proteins and has been used in DNA vaccines. The sequence used is just the promoter gene and does not include any part of the DNA sequence that encodes for the T antigen of SV40. While promoters like the SV40 promoter are used in the manufacturing of mRNA vaccines, they are not considered an ingredient in the vaccines as the vast majority of it is removed during production.

Manufacturing vaccines for a small batch for a trial is a very different process than manufacturing of thousands of doses at a time. Process 1 is the small batch process, while process 2 is the scaled-up version. Although the processes are different, they are both held to the same safety and quality standards.

Original claims that DNA plasmids were found in mRNA vaccines at a higher proportion of mRNA to DNA than is allowed by FDA guidelines stem from a previous preprint paper acknowledging that one limitation of the study is the “unknown provenance of the vaccine vials under study.” They also note that the vaccines arrived without proper cold chain processes and were all expired. They follow up that paper with this preprint, where the authors obtained and tested “24 unopened expired vials” and “three vials of in-date remnants”. As mRNA degrades much faster than DNA, especially when held in suboptimal conditions, any proportion of trace amounts of DNA used in manufacturing would be amplified in expired vials, as these were,  or ones not held in optimal conditions.

Did measles mortality drop before there was a vaccine?

The Claim:

A common anti-vaccine trope is that diseases were on their way out before any vaccines were licensed; therefore, vaccines do not have any effect on disease. This anti-vaxxer’s recent tweet about measles is an example.

The Facts:

Measles is one of the most transmissible infections in humans. One infected person can infect 12-18 others in a group of susceptible people. Prior to vaccines, it was expected that nearly everybody would get measles at some point in their life, usually during childhood. If the measles vaccine conferred no immunity, as the tweeter suggests, measles would still be circulating freely. Instead, almost no one gets measles anymore.

Yes, measles mortality did decline before the introduction of the measles vaccine due to better medical treatments. Measles cases, however, did not decline until after vaccination began. And while people may not have died acutely at the same rates as they did, measles can also lead to blindness, deafness, and SSPE, a type of brain disorder that leads to death years after the initial infection.

This common trope relies on confusing death (mortality) and illness (morbidity). Medical advances slowed down the death rate from measles, but vaccines stopped it.

Just the Facts Newsletter:

Correcting this week's disinformation

Sign up to get a weekly look at the latest vaccination facts as we debunk the latest false vaccination claims making the rounds on the internet.


Back To Top