SALT LAKE CITY – As of Thursday, 714,049 Utahns have been vaccinated against COVID-19. But of these, only 394,004 are completely vaccinated.
This means that 320,045 Utahns have one more blow to do, provided 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 was recently approved for use, requires a single dose.
An AstraZeneca vaccine, probably the next one approved for widespread use in America, requires two doses.
But how much does it matter to get the second dose of vaccine? After all, scientists agree that obtaining a dose of Pfizer and Moderna vaccine will create a certain degree of immunity, introducing the body into a virus with which it was not previously familiar and starting the process of creating antibodies.
Two KSL.com doctors spoke Thursday urging Utahns to end their vaccine course, but said it was crucial for the state to develop the herd immunity it seeks before lifting all coronavirus restrictions.
“Almost 100%” effectiveness
Dr Tamara Sheffield, medical director for community health and prevention for Intermountain Healthcare, said it was not uncommon for vaccines of all kinds to require more than one dose.
“Most vaccines will have multiple doses in a series to stimulate the immune response,” Sheffield said. “In the first year, a child receives the flu vaccine, he needs two doses, because they have not been exposed to the flu vaccine in the past.” Only then, when patients receive the annual flu vaccine, do they need a single dose at a time, Sheffield added.
The second dose of coronavirus vaccine creates a greater and more effective immune response and also makes the response last longer. Human “memory T” cells, Sheffield said, create long-lasting virus prevention and may require more than one exposure to activate.
Estimates vary, but the effectiveness of the Pfizer vaccine after a dose is thought to be about 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, a doctor for infectious diseases at the University of Utah Health, said complete vaccines are “almost 100%” effective in preventing severe illness.
“People kind of get into weeds, well, it’s 70% effective … compared to 90%,” Spivak said. But they all prevent the severe effects of the disease almost entirely, and that’s the important part, she said.
“I think that regardless of the numbers, the real thing you can take at home is that you can take COVID-19 – and I’ve seen it countless times – between the first and second dose,” Spivak said. She encouraged Utahns to remain vigilant even a week or two after receiving the second dose.
“I hesitate for people to be obsessed with the real number – is it 70, or is it 50? – because the answer is that the two doses make it extremely effective. As if it hasn’t been seen so far, except for measles.”
Officials recommend that the two doses of Pfizer-BioNTech vaccine be taken 21 days apart and that Moderna doses be taken 28 days apart. Sheffield and Spivak said it probably doesn’t hurt to wait a little longer, but recommends that Utahns avoid taking a second dose too soon.
Mutations and asymptomatic spread
Sheffield said there are two other big reasons why Utahns should receive the second dose.
The first concerns the immunity of the herd. People who are only partially vaccinated and partially protected, she said, could become unwanted vectors of transmitting the virus. They could be protected from symptoms, Sheffield said, while still transmitting the coronavirus to others.
“When you are partially protected, you may still have the disease, but you can get it, but you do not feel the symptoms,” she said. “So you’re more likely to be a distributor.”
People who are partially vaccinated are also more likely to create new viral mutations, Sheffield explained, as are those that have appeared in Brazil, South Africa and the United Kingdom.
Getting a single dose of the two-shot vaccine creates a “partial or weak” immune response, similar to what happens to an immunocompromised individual, Sheffield said.
“Those individuals who have that weaker immune response tend to be the ones in which we get escaped mutations,” she said. “Viruses that move easily, like the coronavirus – a partially immune individual is one in which these mutations are more likely to survive because they are different and the immune system does not catch them.
“While the usual virus you could control, the mutant virus you don’t control as well.”
For these and many other reasons, Spivak asked Utahns to receive the second dose of vaccine, if necessary. “Please, please, definitely follow the recommendations,” she said. – Take the second dose.