Am I ‘fully vaccinated’? For the last few months I was sure I was — but recent events are making me doubt myself.

Take Monday, when President Biden rolled up his sleeve and presented his unusually hirsute arm for his third Pfizer shot. This followed some federal health advice last week that people over 65, as well as 18-to-64-year-olds with ‘underlying health conditions’ or ‘jobs that increase their risk of developing severe COVID’, are eligible for a third dose of Pfizer.

‘The booster line is if you’re fully vaccinated — the bottom line is that if you’re fully vaccinated and — you’re highly protected now from severe illness, even if you get COVID-19,’ explained the President with his trademark clarity.

Due to a fortuitous run through a hospital parking lot, I secured two doses of Pfizer in March 2021. Back then, we became ‘fully vaccinated’ a full two weeks after completing the course of the COVID vaccine: after your second dose of Pfizer or Moderna or your ‘one-and-done’ Johnson & Johnson. For me, that was mid-April. But is President Biden now ‘more than fully vaccinated’? Or is the definition of ‘fully vaccinated’ about to ‘evolve’ — with the rest of us Pfizerites set to be downgraded, left gazing with suspicion at the other two rows on our CDC cards?

It seems worth asking — the goalposts have shifted so many times over the last 18 months as public health officials squabble over what ‘guidelines’ or ‘mandates’ are ‘necessary’ for us all. Even on the booster shot question, the federal government is divided: a CDC advisory committee voted against allowing it for those at risk because of ‘on-the-job’ exposure, while CDC director Rochelle Walensky overruled them and sided with the FDA, who signed off on the booster for the same group of people last Wednesday. ‘I really do hope that it’s going to be a three-dose vaccine,’ Dr Anthony Fauci told Axios last weekend. Wait, so it’s no longer a two-dose vaccine?

The booster shot question arose due to several factors. First, a small number of breakthrough infections due to Delta and other variants. Second, the varying efficacy of the different vaccines against subsequent variants (Pfizer good, Moderna very good…the poor schmucks overseas who got Sinopharm might as well have injected toilet water into their veins). And third, the gradual waning of antibodies conferred by the vaccines — which, studies indicate, occurs faster than in people who had COVID.

Most Americans didn’t get a say in which shot they got, meaning they didn’t get a say in their level of participation in this discussion. According to several officials, boosters for Moderna and J&J are also in the pipeline. And the US government has written pharmaceutical companies a blank check in the interest of defeating the coronavirus. It seems fair to wonder whether it might be a better use of this money to expand antibody testing, among the vaccinated and the unvaccinated, to get more of a handle on how close to ‘herd immunity’ this country is.

After all, it’s the immune response to the coming iterations of COVID that matters far more than how ‘fully vaccinated’ you are.