A WhatsApp forward is doing the rounds, claiming that polio vaccines are contaminated with “some virus” and warning parents not to give the oral polio vaccine, or its booster, to children. This is fake news of the worst, fear-mongering kind.

Dangerous fake news.

First, the vaccine isn’t contaminated; it’s just an older version of the vaccine. Polio vaccines used to contain mild versions of the three strains of the polio virus: Type 1, 2, and 3. However, once polio type 2 was eliminated from the population in 1999, it was pointless to continue vaccinating against it, and it was phased out of vaccines, which now only include mild versions of type 1 and type 3, since those are the versions still ‘in the wild,’ that is, present among the global population.

In the recent, botched polio vaccination drives in Maharashtra, Telangana and Uttar Pradesh, the vaccines weren’t contaminated — they were just older versions that targeted all three types of polio, even type 2, instead of the more modern vaccines that target only types 1 and 3. There’s no harm to children receiving these shots; they’ll simply be protected against a disease they were never at risk of contracting. There are worse things.

This leads us to recent reports that type 2 polio, the one that was eradicated in 1999, has been found ‘in the wild,’ again — in a Mumbai sewer to be precise, and in a child in UP. This is true — but it doesn’t mean that type 2 polio is flourishing and dangerous again. The polio vaccine, like many vaccines, contains very mild versions of the virus — the exposure to which is what allows vaccinated people to develop immunity to the antigen. These mild strains are evacuated from the body via bodily waste after vaccination. So of course, if an older model of the vaccine, one containing type 2 polio antigens, has been administered — like it was in Maharashtra and in UP — the virus would be expected to show up in sewage and in also, temporarily, in a child who received the vaccine there. This does not mean it’s an active, disease-causing strain — it’s a mild version more suitable to prompting immunity than infection. While public health officials are, of course, monitoring the situation, no one expects this to develop into a situation where type 2 polio ‘is back.’

Unfortunately, ‘botched vaccines’ and ‘polio in the sewage’ sounds terrifying — hence the fear-mongering WhatsApp messages. But it’s actually not. It’s certainly no reason to avoid a polio vaccination or a polio vaccine update for your child.

Bottom line: Skipping a vaccine or booster leaves children more at risk of contracting polio types 1 and 3, which are still present in the general population. And accidentally getting a vaccine that immunizes against all three types, while evidence of gross negligence by the manufacturer, will do more to protect your child than it will do any harm.

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