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According to Loma Linda University Health physicians, there is no evidence that the COVID-19 vaccines cause infertility.

As people across the nation are considering whether to receive a vaccination protecting them from COVID-19, Courtney Martin, DO, FACOG, and Ciprian Gheorghe, MD, PhD, hope to address claims that the vaccination can cause infertility. 

“At Loma Linda University Health, many of our staff are young, female professionals — we understand the importance and severity of this question,” said Martin, medical director of maternity services.

The bottom line

There is no evidence that the COVID-19 vaccines cause infertility.

The claim

Several social media posts have claimed that there is a substantial similarity between the COVID-19 spike protein targeted by the mRNA vaccines and the syncytin-1 protein, which is necessary in developing a healthy human placenta. The claim is that cross-recognition from antibodies between the two proteins occurs due to a five amino acid overlap between both, which leads to infertility.

What we know

According to Gheorghe, a maternal fetal medicine specialist, the chances of having an amino acid overlap like this is very high due to the hundreds of thousands of proteins in a person’s body.

“To get the same five amino acids in a row is statistically probable given the large number of proteins in the human body," he said. "That small overlap is not enough to cause immunogenicity. If five amino acids were enough to cause a cross reaction, a person would have a very high number of cross-reactions to very diverse proteins.”

For any type of cross-reaction, a person would need an extensive matching sequence of much more than five amino acids, he said.

To provide perspective, there are matching sets of five amino acids found in many other known proteins in the human body, Martin said. For example, hemoglobin — the protein in red blood cells that carries oxygen — shares six amino acids with the COVID-19 spike protein. Collagen — the most abundant protein in a person’s body, which supports bones, skin, muscles, tendons, and ligaments — also has an amino acid overlap with the COVID-19 spike protein.

If antibodies to COVID-19 was causing fertility issues, women who have had the COVID-19 illness would not be able to get pregnant after their illness.

“Research is showing that is not the case,” Gheorghe said. “Women are still getting pregnant after having the virus. Women who had the illness early in pregnancy would also be miscarrying if these infertility rumors were true, and we are also not seeing that.”

The COVID-19 vaccines have led to zero deaths — only short-term side effects in some people, such as fever, soreness, headache, etc. This stands in stark contrast to the actual COVID-19 illness, which can cause lung scarring, heart damage, vascular damage, long-lasting symptoms and even death, Martin said.

“This claim was started by two people who decided to put their unsubstantiated thoughts on social media and countless numbers of young women are risking their health because of it,” Gheorghe said.

“After having all the information, it’s important for every person to weigh what they think is a greater health risk,” Martin said. “Talk to a trusted physician, discuss your concerns, and then make a decision, based on evidence, that will keep you safest in the long run.”

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