SALT LAKE CITY – As of Thursday, 714,049 Utahns have been vaccinated against COVID-19. Of these, only 394,004 were fully vaccinated.
This means that 320,045 Utahns still have a chance to go, 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, recently approved for use, requires only one dose.
An AstraZeneca vaccine, probably the next to be approved for widespread use in the United States, also requires two doses.
But how much does it really matter to get the second dose of vaccine? After all, scientists agree that taking one dose of the Pfizer and Moderna vaccine will create some immunity, by introducing the body to a virus for which it was not yet familiar, and the process of creating of antibodies begin.
However, two doctors with whom KSL.com spoke on Thursday urged Utahns to complete their vaccine, saying it was crucial for the state to secure herd immunity before lifting all coronavirus-related restrictions.
‘Almost 100%’ effectiveness
Dr. Tamara Sheffield, medical director of community health and prevention at Intermountain Healthcare, said it was not uncommon for vaccines of all kinds to require more than one dose.
“Most vaccines have multiple doses, in a range, to stimulate the immune response,” Sheffield said. “The first year a child gets the flu vaccine, they need two doses because they have not been exposed to the flu vaccine in the past.” It is only then, when patients get their annual flu shot, that they only need one dose at a time, Sheffield added.
The second dose of coronavirus vaccine creates a larger, more effective immune response and also prolongs the response. These are human “memory T” cells that, according to Sheffield, create long-lasting virus prevention and require more than one exposure to activate.
Estimates vary, but the efficacy of the Pfizer vaccine after one dose is thought to be around 52%, based on its own data. After the second dose, it 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 “almost 100%” effective in preventing serious cases of the disease.
“People get into the weeds of, well, this is 70% effective … versus 90%,” Spivak said. But all almost completely prevent serious consequences of the disease, and that’s the important part, she said.
“I think, regardless of the numbers, the real home is that you can get COVID-19 – and I’ve seen it several times – between your first and second dose,” Spivak said. She encouraged Utahns to stay awake for even a week or two after receiving their second dose.
“I hesitate that people have an obsession with the actual number – is it 70, or is it 50? – because the answer is that the two doses make it extremely effective. Like never before so effective, 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 does not hurt to wait a little longer, but recommends that Utahns not get a second dose too soon.
Mutations and asymptomatic spread
Sheffield said there are two other big reasons why Utahns should get their second dose.
The first is related to herd immunity. People who are only partially vaccinated and partially protected can become, according to her, unconscious vectors of virus transmission. They can be protected from symptoms, Sheffield said while still transmitting the coronavirus to others.
“If you are partially protected, you may still have the disease, you may be able to pass it, but 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 explains, such as those that have emerged in Brazil, South Africa and the United Kingdom.
Getting only one dose of a two-vaccine vaccine creates a “partial or weak” immune response, similar to what happens to an individual with an immune deficiency, Sheffield said.
“The individuals who have the weaker immune response tend to be the ones where mutations escape,” she said. “Viruses that mutate easily, such as coronavirus, are a partially immune individual where the mutations are more likely to survive because they are different and your immune system does not catch them, so they multiply.
“Although you can control the common virus, it is the mutated virus that you also do not control.”
For these reasons and many more, Spivak pleaded with Utahns to get their second vaccine dose if necessary. “Please, please stick to the recommendations,” she said. “Get your second dose.”