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No evidence that COVID-19 vaccines can be sexually transmitted or change people’s blood

Posted on:  2023-10-06

Key takeaway

Available COVID-19 vaccines only use protein fragments of the SARS-CoV-2 virus or genetic information to produce these fragments instead of a full virus. Thus, COVID-19 vaccines cannot replicate in the body nor can they pass from one person to another.

Reviewed content


COVID-19 vaccines can be sexually transmitted to unvaccinated people; vaccines cause blood discoloration and weaken immune system

Source: Facebook, Aaron Lewis, 2023-09-27

Verdict detail

Inadequate support: Available COVID-19 vaccines don’t use technologies that allow viral shedding. There is no biological mechanism that explains how the vaccine would be transferred from one person to another during sexual intercourse.
Factually inaccurate: There is no available scientific evidence supporting the claims that COVID-19 vaccines cause blood discoloration or weaken the immune system.

Full Claim

COVID-19 vaccines can be sexually transmitted to unvaccinated people; vaccines cause blood discoloration and immune system weakening


A video from naturopath Aaron Lewis circulated on social media in September 2023 claiming that COVID-19 vaccines could be sexually transmitted from a vaccinated person to an unvaccinated one.

To support his claim, Lewis showed what was allegedly a micrograph of blood from an unvaccinated person soon after sexual intercourse with a COVID-19-vaccinated individual. Lewis then claimed that the blood started to look like “a vaccinated person’s blood”. Among what Lewis considered to be the hallmarks of a vaccinated person’s blood were blood “discoloration” as well as a large amount of the fungus Candida. Lewis then added that “mass level of candida” “means that the white blood cells are non-responsive”.

Before delving further into the specific claims, we must emphasize that Lewis’ alleged experiment didn’t abide by the most elementary principles of the scientific method. Therefore, the validity and reliability of his observations are highly questionable.

To be reliable, such an experiment should check at least two boxes.

First, it should have a control. In this case, Lewis should have provided a normal blood sample to which he could compare other blood samples. In particular, one should compare the blood sample of an unvaccinated person after sexual intercourse to the blood of the same person before the intercourse and to the blood of a vaccinated person. But Lewis didn’t provide an experimental control.

Second, the experiment should be repeated on a large enough group of people to achieve sufficient statistical power and ensure that the results obtained aren’t due to pure luck. Lewis also didn’t do this.

Furthermore, Lewis’ claims aren’t supported by available scientific evidence.

The first claim is that COVID-19 vaccines can be “shed” from vaccinated people to unvaccinated people. We explained why this can’t happen in a previous review.

Briefly, vaccine shedding is the excretion of viral particles from vaccinated people. But this can only occur in rare cases and only when using live attenuated vaccines. This is because live attenuated vaccines use live virus that can still replicate and generate new viral particles.

However, none of the COVID-19 vaccines currently distributed use live attenuated virus. Available vaccines use either inactivated (“dead”) viruses, isolated viral proteins (the Novavax vaccine), or the genetic information to temporarily produce a single viral protein (the Janssen, AstraZeneca, Moderna, Pfizer-BioNTech vaccines). Therefore, none of these vaccines have the ability to replicate and produce viral particles that could be shed.

Shruti Gohil, associate medical director for epidemiology and infection prevention at the University of California, Irvine, told Politifact that “There is absolutely no biological mechanism for any COVID-19 vaccine side effects or vaccine components to shed to others.”

As a symptom of blood deterioration, the video cites blood discoloration. The claim that vaccination can change blood color isn’t new and several articles explained that it is inaccurate. Blood color can vary depending on many factors, like diet or oxygen level. However, there is no scientific data reporting changes in blood color following COVID-19 vaccination.

Lewis also claimed that the immune system of vaccinated people is weakened, which results in a heavy presence of the fungus Candida in the sample. Again, claims that COVID-19 weakens the immune system have been persistent and recurrent.

Yet, there is no data supporting them, as our previous reviews on the topic can attest. A search on PubMed for scientific articles describing COVID-19 vaccine-associated candidiasis returned no relevant results#. PubMed is a repository of published scientific studies hosted by the U.S. National Institutes of Health.

In fact, studies suggest that COVID-19 increases the risk of fungal infections, including Candida. For example, a study found a higher incidence of Candida infections among critically ill COVID-19 patients compared to non-COVID-19 patients[1] and another suggested that COVID-19 could alter the immune system, thus raising the susceptibility to Candida[2]. Therefore, available evidence suggests that, by reducing the risk of severe disease, COVID-19 vaccines might also reduce the risk of developing COVID-19-associated candidiasis.


# Pubmed search query: COVID-19[Title/Abstract] AND vaccine*[Title/Abstract] AND (candida[Title/Abstract] OR candidiasis[Title/Abstract])


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