COVID-19 vaccines don’t cause leprosy, aren’t responsible for leprosy cases in Florida
CLAIM
COVID-19 vaccines cause leprosy
DETAILS
Incorrect: The increase in reported leprosy cases started before COVID-19 vaccines became available to the public. Thus, vaccination couldn’t have caused them.
Inadequate support: Studies reporting a leprosy reaction in people recently vaccinated against COVID-19 don’t show that vaccines cause leprosy. In fact, leprosy reactions are inflammatory reactions occurring among people who were already infected with leprosy-causing bacteria before being vaccinated.
KEY TAKE AWAY
Leprosy is a disease caused by the bacteria Mycobacterium leprae. Most of the population is already immune to this infection due to natural immunity. It is a slowly progressing disease, with a low risk of transmission, that is curable with a six to twelve months multidrug therapies.
FULL CLAIM: COVID-19 vaccines cause leprosy
REVIEW
A reel posted on Instagram in early January 2024 claimed that COVID-19 vaccines caused leprosy. The video mentioned a surge in leprosy cases in the U.S., where “none of the traditional risk factors are being found” and that medical journals had been establishing a correlation between COVID-19 vaccines and the surge in leprosy cases. The reel was viewed more than 30,000 times.
The video didn’t explicitly use the word “vaccine”. However, multiple elements made it clear that the video blamed COVID-19 vaccines for these cases. First, both individuals appearing in the video made a gesture mimicking an injection in the shoulder when saying the word “medication”. Second, the expression written on the video “Rona V” clearly refers to “coronavirus vaccine”. Third, the video’s caption included the expression “the you know what V”, where “V” clearly stands for “vaccine”.
This isn’t the first time that social media posts claimed COVID-19 vaccines cause diseases. Previous claims associated COVID-19 vaccines with monkeypox and herpes zoster. Health Feedback reviewed the claims at the time and found them to be inaccurate. Here again, a closer examination of the claim shows that it is baseless: COVID-19 vaccines don’t cause leprosy. We explain why below.
Leprosy is a disease known to humanity for thousands of years causing skin and nerve lesions[1]. Its cause is well-known: the pathogen responsible for leprosy is the bacterium Mycobacterium leprae, identified by Norwegian scientist Gerhard Armauer Hansen during the nineteenth century. Nowadays, leprosy still occurs in some countries but is very rare in the U.S.
Contrary to the image conjured by the stigma and fear associated with leprosy, this disease isn’t easily transmitted and it takes prolonged contact with someone with untreated leprosy to get infected. Furthermore, around 95% of all people are naturally immune, meaning most people don’t become sick upon infection. Leprosy is also curable nowadays, with a six-month to one-year combination therapy comprising dapsone, rifampicin, and clofazimine.
The video didn’t provide a source for its allegation of an uptick of leprosy in the U.S. However, it showed part of a webpage from the U.S. Centers for Disease Control and Prevention (CDC) mentioning Florida.
It is possible that the source for this is a case report of a 54-year-old man from Florida with leprosy appearing in the August 2023 issue of the journal Emerging Infectious Diseases published by the CDC[2]. In their report, the authors also mentioned that the incidence of leprosy has gradually increased since 2000, with a total of 159 new cases in 2020, mostly in Florida.
However, Charles Dunn, a third-year resident of the Orlando Dermatology Residency Program and a co-author of the letter, refuted that claim, stating that the observed increase in leprosy started before the distribution of COVID-19 vaccines to the population.
The Associated Press also reported that vaccine safety surveillance systems didn’t detect any increase in leprosy cases following the COVID-19 vaccination campaign in the U.S. Thus, the epidemiological data on leprosy in the U.S. doesn’t support the claim.
It is also inaccurate to say that the leprosy cases in the U.S. weren’t associated with any risk factors. As the case report explains, some cases identified in Florida were caused by a strain of M. leprae identified in local armadillos, strongly suggesting a zoonotic transmission[2].
In a separate interview with NPR, Dunn explained that contact tracing of leprosy isn’t straightforward, because the disease progresses slowly:
“So this is a very slow-growing bacteria that replicates over the course of years. So whenever you’re contact[ed] tracing a bacteria like this, it’s not like I can ask you, where were you 24 hours [before] you contracted this illness? This is the equivalent of me asking you, what did you have for dinner seven years ago?”
Thus, the absence of identified risk factors for some leprosy cases doesn’t mean that they are “atypical” as claimed, but rather that establishing how a person became infected is difficult in the case of leprosy.
Some studies have reported a leprosy reaction among people who had been recently vaccinated against COVID-19[3-5].
However, these reports don’t imply that the vaccine caused leprosy. Instead, the immune response to vaccination might increase the likelihood of leprosy reactions, which are inflammatory reactions in people already infected with M. leprae. Indeed, vaccination and infections caused by other pathogens have been identified before as possible risk factors for developing leprosy reactions[6,7]. Therefore, COVID-19 vaccines don’t cause leprosy; for the vaccine to trigger a leprosy reaction, the person needs to be already infected with M. leprae.
