Amid a slower than expected coronavirus vaccine rollout in the U.S., health officials in the U.K. will focus on giving more people one COVID-19 vaccine dose, which will likely delay their second doses, CNBC reports. Now experts in the U.S. are discussing whether or not an approach like this is worth the risks of deviating from the original vaccine schedule.
There are now two COVID-19 vaccines available in the U.S., one developed by Pfizer and BioNTech and one developed by Moderna. Both of them are administered in two separate doses that are meant to be given a few weeks apart.
Currently in the U.S., for every first dose given, a second dose is reserved for a few weeks down the line to complete the dosing schedule according to the clinical trials. On the other hand, with the U.K. approach, the priority is to use the currently available doses to give as many people as possible their first dose, knowing that this will extend the time between doses beyond the time period studied in the clinical trials while the supply catches up.
But considering the slow rollout of vaccines across the U.S. (only about 2 million out of an expected 20 million doses were given by the end of 2020) and COVID-19 cases continuing to rise, experts are grappling with a new set of questions: Should we stick to the original plan and give everyone in the first priority groups both shots of the vaccines, which might mean holding onto half of those doses for now? Or would it be more valuable to give more people their first dose of the vaccines knowing that we may not have a predictable, steady supply of doses in the future and, therefore, that people could have to wait longer than the recommended time between their doses? And on the more extreme end, could we just give people one COVID-19 vaccine dose without the second? Will we be so short on supply that we need to stretch it out by giving two smaller doses?
Many experts say that it’s best to stick to the original plan for now because that’s what the pharmaceutical companies used in their clinical trials, which means that’s what we have the most relevant data for.
“Stick to the vaccine schedule,” Angela Rasmussen, Ph.D., virologist at Georgetown University Center for Global Health Science and Security, said on Twitter. Even Pfizer and BioNTech agree: “The safety and efficacy of the vaccine has not been evaluated on different dosing schedules as the majority of trial participants received the second dose within the window specified in the study design,” the companies said in a joint statement, Reuters reports.
The Food and Drug Administration (FDA) also released a statement saying that it’s too early to be having any discussion of changing the vaccine schedules. “Without appropriate data supporting such changes in vaccine administration, we run a significant risk of placing public health at risk, undermining the historic vaccination efforts to protect the population from COVID-19,” the statement reads. “We know that some of these discussions about changing the dosing schedule or dose are based on a belief that changing the dose or dosing schedule can help get more vaccine to the public faster. However, making such changes that are not supported by adequate scientific evidence may ultimately be counterproductive to public health.”
“I think it would be good to give the second dose as soon as possible,” Florian Krammer, Ph.D., professor of vaccinology in the department of microbiology at the Icahn School of Medicine at Mount Sinai, said on Twitter. “It is likely that the second dose is needed to generate long-lived and strong immunity.” (To be clear, though, we still don’t know definitively how much protection either vaccine offers.)
On top of the concerns about vaccine efficacy, changing or delaying the schedule could have consequences for the public’s trust in science and medicine. “While there may be strong arguments for halving vaccine doses (and even a delayed dosing strategy) in order to vaccinate as many people as possible, any change from the protocols used in clinical trials will likely further undermine already eroded public trust in vaccines,” Uché Blackstock, M.D., emergency medicine physician and founder of Advancing Health Equity, wrote on Twitter.
“Regarding last-minute changes to vaccination strategy, I’m going to keep beating the same drum for a while,” Natalie E. Dean, Ph.D., assistant professor of biostatistics at the University of Florida, said on Twitter. “Please don’t underestimate the importance of the public having trust in the process for long-term success.”
But there are some reasons why the U.K. approach is worth considering, and an increasing number of experts agree it may be the best course of action—provided that people do get a second dose eventually. “I’ve been thinking about the debate of delayed vs. immediate 2nd dose for some time,” Ashish K. Jha, M.D., MPH, dean of the Brown University School of Public Health and one of the authors of a new op-ed in the Washington Post about vaccine schedules, said on Twitter. “Over past week, have become convinced that getting all doses out now is better. It’s NOT a no-brainer.”
There is evidence from the clinical trials that people do develop some protection from the vaccines within about 10 days after their first dose, Dr. Jha explained. We don’t know whether or not that protection lasts beyond 21 to 28 days (the time between doses in the trials), but considering that the CDC predicts the U.S. could see an additional 100,000 COVID-19 deaths by the end of January, that “most 75 year-olds won’t get their first dose for many more weeks and most 64 year-olds won’t for months, and the new variant will become dominant in that time,” Dr. Jha said we should prioritize getting the first doses out.
“Debate over whether to defer the second dose of vaccine in US misses the obvious first order of business: Stop holding back 50% of doses,” Tom Frieden, M.D., former director of the Centers for Disease Control and Prevention (CDC), wrote on Twitter. “Yes, there’s a risk manufacturers will fall behind production schedule, but that risk is worth taking to get more people vaccinated sooner.”
Ultimately, this is still just a proposal right now. And it’s likely that, depending on the level of spread in a particular community, the delay between doses may matter more or less. But more than anything we need to address the many issues that are making it difficult to vaccinate enough people right now, including vaccine hesitancy, lack of funding for local health departments, and a lack of public health staff to administer the shots.
“Arguments for evaluating a single-dose vaccine regimen rely heavily on the idea that demand greatly exceeds supply (true) & could protect the most people quickly,” Rasmussen said. “That’s all irrelevant if we can’t distribute the supply that we have now.”
This story has been updated to include a statement from the FDA.
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