Both COVID vaccines and the virus itself are "plausible triggers" of the disease, but the study authors specify that vaccines were "more frequently" linked to the ulcers than the virus.
The study also found that the effectiveness of the Pfizer and Moderna vaccines was only 29% during the omicron BA.4 and BA.5 variant phases, 20% during the BQ-dominant phase, and 4% during the XBB-dominant phase.
Under-reporting of injuries following vaccination "should be considered when delivering information to the community and in public health decision-making," the study authors write.
The FDA has "repeatedly stated that effectiveness against transmission remains unproven," the trio write, noting that the agency’s website maintains: "the scientific community does not yet know if Comirnaty will reduce such transmission."
"The conventional SARS-CoV-2 vaccine’s ability to provide immunological protection may be significantly impacted by over-vaccination. If this happens, either newly diagnosed COVID-19 cases or people who have already contracted the virus again may have a more severe case of the illness. This concept was proposed after seeing tolerance of both the humoral and cellular immune responses to prolonged booster immunization doses."