I remember having measles as a kid. Believe me, it was no fun. Also, measles could cause birth defects if a pregnant women got infected. If you were elderly, measles could be fatal.

Eventually, after vaccinations became nearly universal in America, measles was declared eliminated from the US in 2000.

But now the measles are back – already surpassing 700 cases this year, in 22 states. So far, 66 people have been hospitalized, a third of them with pneumonia.

What happened? We stopped vaccinating everyone. More than 500 of the new cases are in people who had not been vaccinated.

Last Monday, the Centers for Disease Control and Prevention renewed an urgent call for parents to have their children vaccinated.

We stopped vaccinating all children because some parents have had religious objections. Others haven’t liked the idea of injecting a live virus into their little ones. Some just never got around to it.

And some parents – succumbing to growing skepticism about science and burgeoning conspiracy theories – believe vaccinations cause autism. The claim has been promoted by Russian internet trolls as well as Donald Trump.

In a 2015 presidential debate, Trump told of an employee with a two-year-old daughter who “went to have the vaccine and came back and a week later got a tremendous fever, got very, very sick, now is autistic”.

Trump has finally stopped pushing this lie. Last week he tersely said “they have to get the shots”, which is about as much of a concession to the truth anyone can expect from America’s liar-in-chief.

In reality there’s zero evidence connecting measles vaccine to autism.

Let’s be clear. To eradicate measles – and other dread diseases such as tuberculosis, polio and tetanus (which also protects from whooping cough and diphtheria) – parents must have their children vaccinated.

Parents have a right to choose what happens to their own children, of course. But the right isn’t absolute.

Parents who abuse their children may lose custody of them. Courts have ordered that children with cancer receive chemotherapy despite their parent’s objections.

There are also the interests of other children and of society overall.

Measles travels through the air. The virus can live for hours after an infected person has coughed or sneezed.

The core issue here is the common good. If enough people are vaccinated, everyone benefits. But if enough people decide to opt out of vaccinations, for whatever reason, they put everyone at a higher risk of contracting disease.

So what’s the incentive to get yourself and your child vaccinated when you might prefer to rely on everyone else vaccinating themselves and their kids instead?

Partly it’s laws that make vaccination compulsory. Yet right now only three states require vaccinations for children to attend kindergarten without any nonmedical exceptions.

Most states give parents a pass if they have religious objections. Nearly 20 states don’t even require that objections be religious – any objection will do.

So the first step is for all states to require vaccinations, or for the federal government to step in and make them mandatory.

At the most fundamental level, vaccination comes down to a duty inherent in being a member of a society

But not even a universal legal requirement would be adequate if enough parents were determined to thwart it.

So at the most fundamental level, vaccination comes down to a duty inherent in being a member of a society.

In all sorts of ways, each of us might prefer to rely on everyone else doing certain things so we don’t have to – whether following mundane norms such as not littering or of giving up our seat on the bus to an older person, or simply obeying laws that are rarely or inadequately enforced, or taking on more heroic roles like teaching in a poor school, being a social worker, serving in the armed services or acting as a first responder.

The idea of the common good was once widely understood and accepted in America. After all, the US constitution was designed for “We the people” seeking to “promote the general welfare” – not for “me the selfish person seeking to do whatever I want for myself and my family”.

Yet the common good is no longer a fashionable idea. We celebrate our personal freedom on Independence Day but pay less heed to our interdependence. We relish our bill of rights but are less attentive to what might be called our bill of responsibilities.

Some demagogues insist our national identity depends on the whiteness of our skin, our European heritage and our English language. And on keeping “others” out.

Rubbish. Our identity depends on the ideals we share and our willingness to sacrifice for the good we hold in common.

Measles are back, largely because some people have stopped vaccinating themselves and their kids against them.

Vaccination against measles and other dread diseases isn’t just a personal choice. It’s a social responsibility.

If we really want to make America great again, social responsibility is the place to begin.