Summary
- Measles is a highly infectious disease that can be prevented through vaccination, with an estimated 57 million deaths averted since 2000.
- Vaccination failure can result in measles infection in immunized persons, with two types of failure documented: primary vaccination failure (no immune response) and secondary vaccination failure (immunity waning over time).
- Measles infection after secondary vaccination failure is generally milder but can still occur, leading to modified measles.
- Persons with secondary vaccination failure have lower measles viral loads in bodily fluids, reducing their likelihood of transmitting the virus.
- Studies show that the risk of onward transmission from persons with measles secondary vaccination failure is very low, suggesting that public health responses could focus on unvaccinated individuals first during large outbreaks.
A recent study conducted by researchers from the University of Queensland has shed light on the risk of measles transmission from individuals who have experienced vaccination failure. Measles, a highly infectious disease, can be prevented through vaccination, but in rare cases, vaccinated individuals can still become infected.
The study, which analyzed data from 14 different studies conducted in high-income countries, found that the risk of measles transmission from individuals with vaccination failure is very low. In fact, the study reported a very low attack rate (0%–6.25%) and an estimated effective reproduction number (Rₑₓ) of 0.063. This suggests that individuals with vaccination failure are much less likely to transmit the virus compared to unvaccinated individuals.
The researchers also noted that the risk of transmission is higher in settings where individuals have prolonged exposure to acutely unwell patients, such as in healthcare settings. However, overall, the risk of measles transmission from individuals with vaccination failure is very low.
While the study highlights the low risk of measles transmission from vaccinated individuals, it also emphasizes the importance of continued vigilance and appropriate public health measures. By directing resources towards unvaccinated individuals and those with primary vaccination failure, public health responses can be more targeted and effective during outbreaks.
The researchers recommend routine serologic testing for vaccination failure, in addition to standard PCR tests, as a useful tool for risk stratification during outbreak management. By enhancing data collection and reporting on measles transmission dynamics after vaccination failure, future public health responses can be better informed and more efficient in controlling outbreaks.
It is important to note that the study had some limitations, including potential publication bias and a small sample size of studies available for analysis. Despite these limitations, the findings provide valuable insights into the risk of measles transmission from individuals with vaccination failure and the implications for public health response strategies.
Infectious Diseases, Pediatrics