I'm given a vaccine requirement form. I have problem understanding the following requirement:

Td/Tdap: YES, substitute 1-time dose of Tdap for Td booster; then boost with Td every 10 years

On my imunization record, I find :

Tdap Unspecified (Tetanus, Diphtheria, Pertussis): 12/18/2017

I can't quite understand if I meet the requirements here. With a quick research, I can see that Td is for adults only, while Tdap is for adolescent and adult. But I'm still having hard time to Understand what "substitute" means.

My understanding: I just need to have had a single shot of Tdap within the previous 10 years. so I'm good.

1 Answer 1


Tdap is the tetanus+diptheria+pertussis vaccine, usually given to adolescents but some people miss it and get as an adult (may also vary by country, but see this CDC page for recommended vaccine ages in the US), and also to pregnant women.

Td is a tetanus+diptheria vaccine given as a booster, typically every 10 years or more frequently if there has been a recent wound/other higher risk exposure. It's not really that Td is for "adults only" but rather that if you are following the recommended schedule adults have had Tdap by the time they are adults, so they'll only be getting the booster, whereas adolescents have either not gotten Tdap so they'd be preferred for Tdap over Td, or they already got Tdap and won't typically need a booster as an adolescent because the inexorable passage of time means they will be adults by the time 10 years have passed. CDC guidance has no problem with Tdap being given instead of Td as a booster, though, if it's more available/convenient (the important bit is that people get the Td booster part; it's not important that they avoid the pertussis part).

It's common for employers to require employees to be up-to-date on these vaccinations because employers don't want to be liable for workers getting infected with tetanus due to an injury on the job.

The first phrasing is pretty nonsensical English. The simplest interpretation is that they require being current on Td/Tdap, which would suggest having a Tdap sometime in the past and either Td or Tdap within the last 10 years. If someone has never had Tdap, then the recommendation would be to get Tdap ("substitute for") one time only, and then to get Td every ten years after that.

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