How a sluggish vaccination program could delay a return to normal and invite vaccine-resistant variants to emerge

The president-elect’s pledge had a certain ring to it: “at least 100 million covid vaccine shots” in 100 days. That was on Dec. 8, before Joe Biden took office. On the fifth day of his presidency, Biden appeared to aim higher, saying 1.5 million shots per day was within reach.

Less than a month into the Biden presidency, as the rate of vaccinations continues to increase, the country has nearly reached the pace needed to achieve that milestone, with 1.48 million shots per day administered over the past week.

[Tracker: How many people have been vaccinated in your state?]

Yet as the country faces a deadly pandemic made even bleaker by emerging and more infectious variants of the coronavirus, which causes the disease covid-19, epidemiologists and public health experts say the Biden administration must set its sights even higher.

“The man on the moon is the kind of goal that we should be aiming for at this point,” said Leana Wen, an emergency physician and public health professor at George Washington University who is also a contributing columnist for The Washington Post. “Having this 1 million a day, or even 1.5 million vaccines a day, is just not aspirational.”

Eric Topol, a cardiologist and founder of the Scripps Research Translational Institute, put it simply: “We can get to 3 [million per day].”

That daily total depends in part on the availability of the vaccine, which is in short supply in the United States. A less-than-vigorous vaccination program would prevent Americans from recovering some semblance of their pre-pandemic lives and would also increase the likelihood that new, potentially vaccine-resistant variants will become dominant in the United States.

This model is useful for understanding how the pace of vaccinations might delay or hasten the end of the pandemic. But like all models, it is a simplification, and many real-world factors complicate the picture.

The forthcoming single-shot vaccine from Johnson & Johnson, which could be available to the public as soon as March, would allow authorities to vaccinate people faster and reduce the number of doses needed to reach herd immunity. Additional vaccines could be available by summer, further alleviating supply issues.

The Biden administration has taken steps to accelerate the vaccination rate, announcing Friday that it would deploy military personnel to create mass-vaccination centers and invoke a Korean War-era law to ensure Pfizer has access to needed equipment to scale up production of its vaccine.

On the other hand, children under 16 are, at least for now, ineligible to receive the vaccine, so a larger share of adults will need to get vaccinated for the whole U.S. population to reach herd immunity.

And while some people who already caught the coronavirus are probably contributing to herd immunity, it remains unclear how long they will remain immune. The Centers for Disease Control and Prevention recommends that people with prior infections should still be offered the vaccine because “reinfection is low in the months after initial infection but may increase with time due to waning immunity.”

Their immunity may soon become even shorter as new, more infectious variants emerge and spread.

‘Evolving like mad’

Biden and public health officials are racing against a minuscule but pliable opponent. The novel coronavirus replicates by invading a person’s cells and effectively turning them into factories, each of which can produce hundreds of thousands of copies of the virus.

Over time, errors occur in the duplication, resulting in slightly modified versions of the virus. Often, these mutations will have no noticeable effect on the virus. But given enough time, mutations will emerge that make the virus more dangerous.

For instance, when a person with a compromised immune system is infected, a prolonged battle with the disease can result in mutations to the virus that help it elude the body’s immune response, resulting in what scientists call an “escape variant.”

“Certain people who don’t have a good immune system, they go into accelerated evolution of mutations. That’s where we think the bad boys have come from,” Topol said. “They never conquered their infection, and it just keeps evolving like mad.”

Not only could variants like these short circuit the immunity of those who were infected with earlier coronavirus strains, they could also reverse progress toward herd immunity, requiring people who have been vaccinated to get new shots in the future.

Vaccination delays could hamper Biden’s initial priority of controlling the outbreak: Public health experts fear that, left unchecked, these mutations could extend the pandemic’s end by months or even years.

“Part of the reason we discuss herd immunity is to say, first of all, you can be vulnerable to having severe effects from coronavirus, even if you’re previously young and healthy. That’s a medical fact,” Wen said. “But also the reason we get vaccinated is not just to protect us, it’s to protect others around us.”