When I made a pro-vaccination comment on Facebook recently I wasn't prepared for the backlash. I'd replied to a friend's post – a chart comparing the small number of vaccines children had in the 1940s to the much larger number they have now. Were so many vaccines a good idea, she wondered?

Yes, I wrote, explaining that I'm old enough to have lived through outbreaks of one of the scarier diseases that vaccination prevents: polio. As a child in the UK in the late 50s, you couldn't avoid the newspaper photos of kids encased in iron lungs – the coffin-like contraptions that helped them breathe. Polio can paralyse the respiratory system or spine. It can kill or leave you crippled – and I still remember the relief of lining up for the vaccine at school, knowing I'd be protected. So, yes, I said on Facebook, immunisation is good.

There is a strong consensus within the scientific community that vaccines don't cause autism. Credit:Wayne Taylor

The response to this was swift. I was misguided about immunisation preventing polio, the first commenter said – it was better sanitation, not vaccines, that brought the outbreaks to an end. More posts rolled in offering links to information questioning the value of immunisation. It was futile to answer back.

This was one of a few conversational brushes with vaccination I've had lately – some with mothers of small children concerned about too many vaccinations overloading young immune systems or with friends asking me if I think autism and immunisation are linked.