Hey there, time traveller!
This article was published 18/4/2015 (2100 days ago), so information in it may no longer be current.

These days there's lots of news about vaccinations. There's good news and there's bad news. Let's unscramble them; maybe we can learn from both.
There is good news about Ebola vaccines. Ebola is about eight times less infectious than measles but it's far more deadly. It's a gruesome way to die. Tom Clancy's novel, Executive Orders, depicts an Ebola epidemic in the United States. It's fiction but its gruesome details of the suffering Ebola brings to those whom it infects are facts. You would not wish it on an enemy. Today, unsung heroes are bringing the Ebola epidemic under control in West Africa. Yet they have no cure to offer; they can only isolate its victims to survive or die. Ebola will be back someday, emerging from the jungle. That's where it hides, that's what it does. The good news is by then the world should have at least one vaccine and some data showing it will work. And, faced with Ebola, no one rejects a vaccine.
Then there is news of those who, with good intentions, oppose vaccines. To appreciate the issues that they raise, let's look at what a vaccine is. It is an agent that imitates a micro-organism (a.k.a. a bug) that causes a disease. It must be a good imitation to immunize you, but not so good that you get the disease. There are three main kinds: a disabled version of the bug; or fragments of the bug; or a like organism that won't make you sick. Each exposes you to something you could meet in nature if you were so fortunate. What each does in its own way is train your immune system to attack the bad bug fast. In other words, a vaccine does what an infection does without the ill effects.
A practical vaccine has more ingredients. Think of this like baking bread. You may see bread as nutrition made from wheat. But the baker adds ingredients for purposes such as stopping mould, improving taste, and keeping fresh. Likewise, many vaccines include additives to preserve them better or to make them more effective with a lower and so less expensive dose. For example, the Public Health Agency of Canada's laboratory in Winnipeg created a pure Ebola vaccine; NewLink Genetics and Merck Vaccines are using it to make a practical Ebola vaccine and you can bet they will use additives.
Thoughtful parents want to know about the fine print on vaccines for their kids. Good for them! But not so good if they don't find the facts. Some find false stories instead. Fact is vaccines and their additives are subject to testing and reporting and strict regulation. Fact is, too, there is no guarantee they are completely safe. Nothing is. But their risks are very small; their benefits are huge. Their benefits compare with those of running water we can safely drink. No doubt additives obscure the vaccine good-news story. But additives are just one aspect of the larger anti-vaccine push. Let's not mince words here: Civilization as we know it can't survive without vaccines. The risks from not being vaccinated against many common diseases are far worse than any risks from the vaccines. Those wholesale anti-vaccine stories are untrue; some are frankly fraudulent.
These false stories have sad consequences. For example, measles is much less deadly than Ebola but measles does kill kids and does ruin lives. The victims of the anti-vaccine stories include children of parents who believe the stories. They include others who have reasons (such as weak immune systems) why they can't get vaccinations; they may succumb to bugs they catch from those who can but don't.
Measles vaccination rates in North America are now lower than the rates in 16 countries in Africa! We can do better than this. Vaccination is not only sensible and safe, it's a duty that we all owe to the rest of us.
Colin Gillespie is a physicist and author whose most recent book is Time One: Discover How the Universe Began. He writes a weekly web blog Science Seen.