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Tara C. Smith A Covid vaccine can save America — but not if we can't convince Americans it's safe

As vaccines from Moderna, Pfizer and AstraZeneca/Oxford University head into the final stretch, a number of questions remain, including how the public will respond to their release.

We are in a dark place right now. Watching surges of Covid-19 in the spring and summer was like following a bouncing ball across the country: from San Francisco Bay to New York to Washington state, Michigan, Florida and Arizona. Case numbers oscillated in many areas, ticking up after holidays and then slowing down for a bit. More states instituted mask mandates; in states lacking them, many cities made their own. Health care workers from other states where cases were low were brought in to help in hard-hit locales.

And then came November.

Dr. Rick Bright warned in May that the U.S. could see its “darkest winter” if we didn’t get the virus under control. We’re there now.

Now, we’re seeing record case numbers in almost every state. Since November 1, we’ve added over three million new cases in the U.S.; right now we're averaging around 170,000 new cases diagnosed every day. At the beginning of the month, we were at closer to 80,000 per day. And thousands of deaths are following. Dr. Rick Bright, a member of President-elect Joe Biden’s coronavirus task force, warned in May that the U.S. could see its “darkest winter” if we didn’t get the virus under control. We’re there now.

But like any good drama, it’s always darkest before the dawn. Press releases about vaccines developed by Moderna, Pfizer, and AstraZeneca/Oxford University suggest that all three are safe and effective, and will be looking for Food and Drug Administration (FDA) approval soon. Pfizer has already applied for an Emergency Use Authorization.

We could be headed for an embarrassment of riches when it comes to vaccines to slow the pandemic — but as the vaccines head into the final stretch of testing and approvals, a number of questions remain, including how the public will respond to their release. Most importantly — how do we know these are safe and effective?

Earlier this spring, we saw the first signs of danger as anti-vaccine groups and coronavirus conspiracy theorists started to adopt similar rhetoric. To combat this “unholy alliance,” as I wrote previously, transparency will be key to rebuild diminished trust, counter false beliefs, and assuage fears. Vaccine development was unfortunately politicized, to the point that the FDA had to reiterate that it would follow its own guidelines on vaccine approval. Many Americans are already nervous about vaccines developed so quickly, so clear data on their effectiveness and potential side effects are important. To add to this, all three use new or new-ish technology.

Though all three vaccines target the virus’s spike protein (which binds to host cells), they do it in different ways. The Pfizer and Moderna vaccines use mRNA technology, which carries the instructions to make the viral protein — the host immune response then recognizes it as foreign. The AstraZeneca/Oxford vaccine uses a chimpanzee adenovirus that carries genetic instructions for the SARS-CoV-2 spike protein. None of the companies have published results of their Phase III clinical trials yet, but must release this data to FDA in order to gain approval.

Once that happens, which vaccine to get? The consensus for that seems clear: whichever one is available in your area. Vaccine developer Dr. Peter Hotez noted in an interview that once a vaccine is approved by the FDA, “Don't overthink it. Don't wait. Get what vaccine you can.”

Vaccines will likely be tiered in distribution so that individuals at the highest risk get vaccines early on before the general public, including health care workers, individuals in nursing homes and prisons, other essential workers, and individuals who are at high risk due to age or other conditions will be among those who receive the vaccine perhaps late this year or early in 2021. Specifics of this distribution will likely vary state to state.

For the three vaccines closest to approval, all are two-dose vaccines, meaning you get the initial shot and then need to return for another dose a few weeks later. What if a person has a mild reaction to the first shot — could they get a different vaccine for the booster dose? Virologist Angela Rasmussen of the Georgetown Center for Global Health Science and Security cautions that there are “currently no data about mixing vaccines” and therefore moving between one vaccine and another should be avoided. This may be tested later once the vaccines are approved and in wide use, but for now, finalizing the ongoing studies and moving the vaccines toward distribution is the primary goal.

Which brings up the next question: How long will immunity last? Almost a year after the discovery of SARS-CoV-2, there’s still a lot of uncertainty about how long immunity can protect against a natural infection, with some suggesting it could last for “years” and others that it may be only months. For the vaccines, we won’t know how long vaccine-induced immunity lasts until we’re able to follow a large number of vaccinated individuals over time.

Though some have compared the Covid-19 vaccine to yearly influenza shots, there are some differences. Rasmussen explains, “This will be a little different than the annual influenza booster since that's needed in part because of new flu strains circulating. Right now, there is only one strain of SARS-CoV-2 circulating as far as the immune system is concerned.” She also explains that SARS-CoV-2 has a lower mutation rate than influenza and is unable to change rapidly by reassortment — a shuffling of gene parts with related viruses — as the flu does. This means that a need for a repeat vaccination each season will be driven more by the durability of the host’s immune response than the emergence of distinct strains of coronavirus.

At what point, then, can we begin to act and feel “normal” again as a society? I’d caution against putting the cart before the horse. The hope is that most individuals in the U.S. who want the vaccine will be able to receive it by summer 2021. There is some disagreement about the exact level of protection needed in the population to reach herd immunity from vaccination, but generally it is assumed to be about 60-70 percent of the population that needs to be immune to the virus; reaching this threshold would then significantly reduce the chances of viral spread.

Sixty percent of the U.S. population is about 200 million individuals. But more than that number need to be vaccinated, because vaccination isn’t a guarantee of immunity — vaccines are not 100 percent effective. If we assume the combination of the three pending vaccines would average out to about 90 percent based on their distribution and use in the population, that means that closer to 225 million would have to receive the vaccine.

Another wrinkle? The vaccines have not yet been fully tested in children; Pfizer and AstraZeneca recently began such tests, and Moderna will begin soon. That means that approximately 80 million children cannot yet be vaccinated. Tests have also not yet been done on pregnant women, which account for about 16 million people at any time point. That leaves roughly 234 million potentially eligible Americans. About 96 percent of those eligible would need to be vaccinated.

A recent Gallup survey (carried out before news of the potential vaccine efficacy was released) suggested that about 58 percent of Americans would get a Covid-19 vaccine.

And that brings us back to the vaccine hesitant minority. A recent Gallup survey (carried out before news of the potential vaccine efficacy was released) suggested that about 58 percent of Americans would get a Covid-19 vaccine. Even with a perfect vaccine, that’s not enough. Encouraging individuals to get vaccinated is difficult, as there is already considerable misinformation about a Covid-19 vaccine— misinformation that has circulated for months.

The response to the pandemic has also been highly politicized, making vaccination programs even more difficult to promote. The Gallup survey found that political identification factored into willingness to take a vaccine, with Democrats more likely and Republicans more hesitant. This may mean that some pockets of the country could reach herd immunity locally, while others, where vaccine uptake is lower, could struggle with cases for a longer period of time.

Personally, I’m planning to get myself and my family vaccinated as soon an FDA-approved vaccine becomes available to me. But I’m also expecting to stay at least partly in “pandemic mode” for much of 2021. I am hoping to do some late summer travel, to spend time with extended family members, and maybe even eat in a restaurant or go to a movie again at some point next year.

But for the foreseeable future, I’m also planning to continue to wear my mask and minimize unnecessary public outings, regardless of my personal vaccine status. Vaccination ultimately will be our most important long-term advance against this pandemic, but like masks, it works best when use is high within the community. Slowing this pandemic is within our reach — but will we do it?

Listen to Tara Smith discuss the consequences of an anti-vaccine unholy alliance on "Modern Ruhles," a new podcast from Stephane Ruhle and NBC News THINK, available on the iHeartRadio App, Apple Podcasts or wherever you get your podcasts.