Public trust in vaccines appears to be waning. The percentage of Americans who agree that vaccinations are "crucial" to health has fallen by as much as 10 points in a decade.

When asked in 2008, 80 percent of Americans agreed that vaccinations were "very important" for the health of society. Fast-forward 10 years later and just 70 percent share that same sentiment. Meanwhile, the number of people who believe that vaccines are "somewhat important" has risen from 17 percent in 2008 to 22 percent in 2018. This is matched by an increase in those who believe vaccines are "not too important" or "not at all important". 

These figures are based on a poll recently conducted by public health non-profit Research!America, working in collaboration with Zogby Analytics. The survey involved a nationally-representative sample of 1,004 and claims to be accurate to a margin of plus or minus 3.1 percentage points.

The poll also revealed a decline in the number of people who trust in the safety of vaccinations, despite numerous studies that have shown side effects are extremely rare and that they do not cause autism (even in dogs). Thirty-two percent say they are "very confident" in vaccination safety (equal to 2008) and 45 percent are "somewhat confident", dropping 8 percent since 2008. Six percent admit they are "not at all confident".

While clearly the majority still support vaccinations, this is a worrying trend considering that vaccines are one of the most effective healthcare actions, both in terms of cost and lives saved – large-scale vaccination programs in developing countries are expected to save $820 billion (and 20 million lives) by 2020.

The good news is that this anti-vaxxer attitude doesn't seem to have much of an effect on actual vaccination levels (at least, not yet). Nancy Messonnier, the director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention, told US News that nationally, fewer than one in a hundred children are unvaccinated.

But if this were to change and fewer children were to be immunized, it could threaten the concept of "herd immunity". That is, if the vast majority of the population is immune, it slows down the spread of disease to such an extent that it protects even those who are not (children and adults going through chemotherapy, for example). For polio, this would mean 80 to 85 percent of people would need to be vaccinated, whereas, for a faster spreading disease such as measles, 90 to 95 percent would.

Already the US is seeing outbreaks of diseases, like measles, that are preventable – there were 6,503 incidents of vaccine-prevented disease in 2017 compared to 99 in 2008, as you can see for yourself in the map here.