The Pacific Northwest is dealing with an outbreak of the measles, and that is prompting many to wonder how the measles made a comeback.
The virus that causes the measles spreads quite easily, and while many people afflicted with the disease make a full recovery without any serious, long-term complications, others won’t. In some cases, the infection can lead to pneumonia, encephalitis, premature birth, and even death.
While there can be a variety of reasons that certain infectious diseases make their way through a population, this particular outbreak seems to be affecting those who haven’t complied with recommended vaccinations.
According to the concept of herd immunity (sometimes called community immunity), a threshold percentage of a population needs to have protection from a pathogen to provide a level of protection to those members of the population who aren’t protected. That protection typically comes in the form of vaccinations.
While no vaccine is 100% effective, studies have shown that after one dose of the MMR vaccine (which is usually given between 12 and 15 months of age), 93% of patients receive immunity. After the second recommended dose (which is often given between 4 and 6 years of age), 97% of the population achieves protection. It is also believed that when a community is 93-95% protected against the measles virus, the level of herd immunity with this disease can be reached.
But as vaccination compliance rates fall, the number of potential hosts in the population increases, and the more hosts there are, the more viruses there will likely be. And the more viruses there are, the greater the potential is for mutations that can even threaten protected members of the community!
Many members of the population can’t be vaccinated against such diseases, either because of age, family history of adverse reactions, or being in an “immunocompromised” (weakened immune system) state.
When it comes to gathering information that the community needs to approach outbreaks such as these, the internet can be a source of misinformation, almost as much as it can serve to provide credible, peer-reviewed data. Stopping to conscientiously consider the credibility of sources can go a long way in terms of keeping our communities safe and healthy.