SALT LAKE CITY – As of Thursday, 714,049 Utahns have been vaccinated against COVID-19. But only 394,004 of these have been fully vaccinated.
That means 320,045 Utahns still have a chance, provided they receive 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 that was recently approved for use only requires one dose.
An AstraZeneca vaccine, probably the next approved for widespread use in America, also requires two doses.
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 vaccines will create a degree of immunity, introduce the body to a virus it was previously unfamiliar with, and the process of creating it. of antibodies would start.
Two doctors KSL.com spoke to on Thursday urged Utahns to complete their course of vaccination, saying it is critical for the state to develop the herd immunity it seeks before all coronavirus-related restrictions are lifted.
‘Nearly 100%’ effectiveness
Dr. Tamara Sheffield, medical director of community health and prevention at Intermountain Healthcare, said it’s not uncommon for all kinds of vaccines to require more than one dose.
“Most vaccines will have multiple doses in a row to boost the immune response,” Sheffield said. “The first year a child gets the flu vaccine, they need two doses because they haven’t been exposed to the flu vaccine in the past.” Only after that, when patients get their annual flu shot, do they only need one dose at a time, Sheffield added.
The second dose of the coronavirus vaccine produces a larger, more effective immune response and also makes that response last longer. It’s the “memory T” cells of humans, Sheffield said, that create long-term virus prevention and may require more than one exposure to activate.
Estimates vary, but based on our own data, the effectiveness of the Pfizer vaccine is believed to be about 52% after a single dose. After the second dose, that jumps to about 95% – an almost unprecedented level of protection for modern vaccines, doctors say.
Dr. Emily Spivak, an infectious disease physician at the University of Utah Health, said the complete vaccines are “nearly 100%” effective in preventing severe cases of the disease.
“People are crawling in the weeds of, well, this one is 70% effective … versus 90%,” Spivak said. But all of them almost completely prevent serious consequences of the disease, and that’s the most important part, she said.
“I think, regardless of the numbers, the real benefit is that you can get COVID-19 – and I’ve seen it several times before – between your first and second dose,” said Spivak. She encouraged Utahns to stay vigilant even for a week or two after getting their second dose.
“I hesitate for people to obsess over the actual number – is it 70, or is it 50? – because the answer is that the two doses make it extremely effective. Effective as never before, except maybe for measles.”
Officials recommend that the two doses of the Pfizer-BioNTech vaccine be taken 21 days apart and that Moderna doses be taken 28 days apart. Sheffield and Spivak said it probably wouldn’t hurt to wait a little longer, but Utahns recommend not getting a second dose too soon.
Mutations and asymptomatic dissemination
Sheffield said there are two other main reasons why Utahns should be getting their second dose.
The first concerns the immunity of the herd. People who are only partially vaccinated and partially protected could become unwitting vectors of virus transmission. They can be protected from symptoms, Sheffield said, while still transmitting the coronavirus to others.
“If you’re partially protected, you may still have the disease, you can still get through it, but you may not feel the symptoms of it,” she said. “So you’re more likely to be a spreader.”
Partially vaccinated individuals are also more likely to create new virus mutations, Sheffield explained, such as those originating in Brazil, South Africa and the UK.
Getting just one dose of a dual vaccine creates a “partial or weak” immune response, similar to what happens with an immunocompromised individual, Sheffield said.
“Those individuals with that weaker immune response are usually the ones in whom we get escaped mutations,” she said. Viruses that mutate easily, like coronavirus – a partially immune individual is one where those mutations are more likely to survive because they’re different and your immune system doesn’t catch them. So they proliferate.
“While you may be able to control the common virus, you also have no control over the mutated virus.”
For those and many more reasons, Spivak pleaded with Utahns to get their second dose of vaccine if needed. “Please, please do stick to the recommendations,” she said. “Get your second dose.”