SALT LAKE CITY – Until Thursday, 714,049 Utahns were vaccinated against COVID-19. But, of these, only 394,004 are fully vaccinated.
This means that 320,045 Utahns still have another chance, as long as they have received one of the vaccines developed by Pfizer-BioNTech or Moderna; both require two doses for maximum effect. A third vaccine developed by Johnson & Johnson, which has recently been approved for use, requires only one dose.
An AstraZeneca vaccine, probably the next approved for widespread use in America, requires two doses as well.
But how much does it really matter to take the second dose of the vaccine? After all, scientists agree that receiving a dose of the Pfizer and Moderna vaccine will create some degree of immunity, presenting the body with a virus it was not familiar with and starting the process of creating antibodies.
Two doctors KSL.com spoke to on Thursday asked Utahns to complete the vaccine course, however, saying it is crucial for the state to develop the collective immunity it seeks before lifting all restrictions related to the coronavirus.
‘Almost 100%’ effectiveness
Dr. Tamara Sheffield, medical director of community health and prevention at Intermountain Healthcare, said it is not uncommon for vaccines of all types to require more than one dose.
“Most vaccines will have multiple doses, in series, to stimulate the immune response,” said Sheffield. “In the first year that a child receives the flu vaccine, they need two doses because they have not been exposed to the vaccine in the past.” Only after that, when patients get the annual flu shot, do they only need one dose at a time, Sheffield added.
The second dose of the coronavirus vaccine creates a larger and more effective immune response and also makes that response last longer. It is the “memory T” cells of humans, said Sheffield, that create long-term viral prevention and may require more than one exposure to activate.
Estimates vary, but the effectiveness of the Pfizer vaccine after a dose is believed to be about 52%, based on its own data. 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 complete vaccines are “almost 100%” effective in preventing severe cases of the disease.
“People kind of get the weeds from, well, this is 70% effective … versus 90%,” said Spivak. But they all prevent the serious effects of the disease almost entirely, and that is the important part, she said.
“I think that regardless of the numbers, what really matters is that you can get COVID-19 – and I’ve seen it several times – between the first and the second dose,” said Spivak. She encouraged the Utahns to remain vigilant even a week or two after receiving the second dose.
“I hesitate that people are obsessed with the real number – is it 70 or 50? – because the answer is, both doses make it extremely effective. As never seen before, effective, except maybe for measles.”
The authorities recommend that the two doses of the Pfizer-BioNTech vaccine be administered 21 days apart and that the doses of Moderna be administered 28 days apart. Sheffield and Spivak said it probably doesn’t hurt to wait a little longer than that, but recommend that the Utahns avoid taking a second dose too soon.
Asymptomatic mutations and dissemination
Sheffield said there are two other major reasons why the Utahns should receive their second dose.
The first is related to herd immunity. People who are only partially vaccinated and partially protected, she said, can become involuntary vectors for the transmission of the virus. They could be protected against symptoms, Sheffield said, while still passing the coronavirus on to others.
“When you are partially protected, you may still have the disease, still be able to transmit it, but you may not feel the symptoms of it,” she said. “So, you’re more likely to be a propagator.”
Partially vaccinated individuals are also more likely to create new virus mutations, Sheffield explained, like those that originated in Brazil, South Africa and the United Kingdom.
Receiving just one dose of a double vaccine creates a “partial or weak” immune response, similar to what happens to an immunocompromised individual, Sheffield said.
“Individuals who have a weaker immune response tend to be those in which the mutations escape,” she said. “Viruses that mutate easily, such as the coronavirus – a partially immune individual is one in which these mutations are more likely to survive, because they are different and their immune system cannot detect them. Then, they proliferate.
“Although the normal virus you can control, the mutant virus you can’t control either.”
For these and many other reasons, Spivak begged Utahns to get his second dose of vaccine, if necessary. “Please, please, definitely follow the recommendations,” she said. “Take your second shot.”