SALT LAKE CITY - As of Thursday, 714,049 Utahns have been vaccinated against
COVID-19. But of those, only 394,004 are fully vaccinated.
That means 320,045 Utahns still have another shot to go, provided they
received one of the vaccines developed by Pfizer-BioNTech or by Moderna;
both require two doses for maximum effect. A third vaccine developed by
Johnson & Johnson,
which was recently approved for use, requires only one dose.
An AstraZeneca vaccine,
likely the next approved for widespread use in America, requires two doses as well.
But how much does it really matter to get the second dose of the vaccine?
After all, scientists agree that getting one dose of the Pfizer and Moderna
vaccine will create some degree of immunity, introducing the body to a
virus it was previously unfamiliar with and starting the process of antibody creation.
Two doctors KSL.com spoke to Thursday urged Utahns to finish their course
of the vaccine, though, saying it’s crucial for the state to develop
the herd immunity it seeks before lifting all coronavirus-related restrictions.
‘Nearly 100%’ effectiveness
Dr. Tamara Sheffield, medical director of community health and prevention
for Intermountain Healthcare, said it’s not uncommon for vaccines
of all kinds to require more than one dose.
“Most vaccines will have multiple doses, in a series, in order to
stimulate the immune response,” Sheffield said. “The first
year a child gets the influenza vaccine, they need two doses because they
have not been exposed to the influenza vaccine in the past.” It’s
only after that when patients get their yearly flu shot that they only
need one dose at a time, Sheffield added.
The second dose of the coronavirus vaccine creates a greater, more effective
immune response and also makes that response last longer. It’s humans’
“memory T” cells, Sheffield said, that create long-lasting
virus prevention and may require more than one exposure to activate.
Estimates vary, but the Pfizer vaccine’s effectiveness after one
dose is believed to be about 52%,
based on its own data. After the second dose, that jumps to roughly 95% - a nearly unprecedented
level of protection for modern vaccines, doctors say.
Dr. Emily Spivak, infectious disease physician at University of Utah Health,
said the full vaccines are “nearly 100%” effective at preventing
severe cases of the disease.
“People sort of get in the weeds of, well, this one is 70% effective
... versus 90%,” Spivak said. But they all prevent severe effects
of the disease almost entirely, and that’s the important part, she said.
“I think regardless of the numbers, the real take-home is that you
can get COVID-19 - and I have seen it numerous times - between your first
and second dose,” Spivak said. She encouraged Utahns to stay vigilant
even a week or two after they’ve received their second dose.
“I hesitate for people to obsess about the actual number - is it
70, or is it 50? - because the answer is, the two doses make it extremely
effective. Like, never-seen-before effective, except maybe for measles.”
recommend that the two doses of the Pfizer-BioNTech vaccine are taken 21 days apart
and that Moderna doses are taken 28 days apart. Sheffield and Spivak said
it probably doesn’t hurt to wait a little bit longer than that,
but recommend that Utahns avoid getting a second dose too soon.