Vaccines get a lot of bad press about side effects. Some are real, like myocarditis with mRNA Covid vaccines and thrombocytopenia with the MMR vaccine. But fears about other vaccine side effects still permeate the Internet despite solid scientific evidence showing no relationship to the vaccine, like autism risk and the MMR vaccine.
Some adverse side effects are expected and looked for during a vaccine’s pre-licensure trials, eg, injection site reactions or a sore arm. Occasionally, rare but real side effects are detected after licensure resulting in the vaccine being removed from the market. The original rotavirus vaccine, RotaShield, was voluntarily removed from the market in 19991 when an increased risk of intussusception of 1 in 10 000 vaccine recipients was proven.
On the other hand, occasionally a “good” side effect associated with a vaccine turns up. For example, 3 papers recently published in Lancet Infectious Diseases report a protective effect from a meningococcal vaccine against gonorrhea. Case-controlled observational studies from the Centers for Disease Control and Prevention (CDC), on US data,2 and one from Australia3 both showed efficacy and the third, from the UK,4 found use of the meningococcal shot to prevent gonorrhea infections cost effective. These could be encouraging findings given that the need for a good vaccine against gonorrhea is high.
Take a quick 2-question quiz on this STI and the potential for vaccine cross-protection.