Now that boosters are becoming more widely available, questions have arisen as to what being fully vaccinated means – is it the first two doses or is it all three.
"I personally don’t like the term fully vaccinated," said Dr. Robert Siegel, a professor of microbiology and immunology at Stanford University, on Thursday’s Ask an Expert with KCBS Radio's Holly Quan and Dan Mitchinson.
“Fully vaccinated is not an immunological term, it’s actually sort of a policy term,” said Siegel.
Instead, it’s better to go with sufficiently vaccinated. "That way you realize that this can change over time," he said.
As of right now, the current definition of the policy term "fully vaccinated" is having the two shots for the majority of people, and that’s likely to remain the case until the boosters are made available to everyone.
The definition can change due to a variety of factors, such as the variants of the virus in circulation, differences in individual immunological response, changes in manufacturing or delivery protocols, and the prevalence of the virus in the population, said Siegel.
Being fully vaccinated would look different for someone who is immunocompromised versus someone who isn’t, he said.
And as science and innovation progress, policies change as well.
The recent approval of the vaccine for children aged 5-11, the authorization for the Johnson & Johnson and Moderna boosters, and the ability to mix and match vaccines have all been major recent policy changes affecting the concept of being fully vaccinated.
The reason, "the key" to why so much emphasis is placed on the term fully vaccinated boils down to policies related to in-person attendance in the workplace, in public spaces, at public events. "Whatever the definition of fully vaccinated at the time will be reflected in what companies ask for," said Siegel.
But the definition is unlikely to change too much until booster shots are disseminated to the general population.
Booster is also a term that shouldn’t be given too much weight, said Siegel. Except if a person is immunocompromised. "The third dose is really considered to be a part of the initial series and then they are now eligible for a fourth dose so they can properly boost their immune system," he said.
It takes about two weeks for the third dose to boost a person’s immunity, but regardless, it’s still the first dose that is the most important, he said. "The second dose is the second most important and the third dose gives you this incremental protection against acute disease."
