Hillary Clinton

Mitch McConnell/Facebook

U.S. Senator Mitch McConnell weighed in on the 2016 presidential race at a luncheon in downtown Lexington Thursday. 

As the measles outbreak continues to spread, political leaders with an eye on the White House in 2016 spent much of the week jumping into, and then trying to bail themselves out of, the vaccine debate.

Some brushed the issue off as an unnecessary media circus, but it's worth taking a look at its deeper political meaning. Here are five things the vaccine politics kerfuffle of 2015 tells us about the emerging field of presidential candidates for 2016.

1. Vaccination politics are a problem for Republicans — not Democrats.

Hillary Clinton: The Fresh Air Interview

Jun 12, 2014

Hillary Clinton is on a national book tour for her new memoir, Hard Choices. The book outlines her four years as secretary of state during President Obama's first term, when she met with leaders all over the world.

One of her priorities was to campaign for gay rights and women's rights. She says she saw the "full gamut" on how women were treated, and in some cases it was "painful to observe."

In a new survey released Wednesday, Public Policy Polling found that in a hypothetical 2016 presidential race Democratic Hillary Clinton leads Republican Sen. Rand Paul in Kentucky.

Clinton is the outgoing U.S. Secretary of State who many Democrats want to run in four years, while Paul is a rising GOP star and Tea Party favorite. Both are rumored presidential candidates at this point, but the PPP survey shows Clinton ahead of Paul by a 5-point margin in the commonwealth at 47-to-42 percent.

A large reason for Clinton's lead is that she is far more popular in Kentucky than President Obama, who has struggled amongst state Democrats.

From PPP:

Clinton has a 48/42 favorability rating with Kentucky voters. By comparison Barack Obama's approval rating is 38/59.