Vaccines Q & A

Q&A: U.S. Vaccine Supply Appears To Be Surpassing Demand

The United States government and partners in the pharmaceutical industry developed, manufactured, and evaluated safe and effective COVID-19 vaccines in record time. A massive national vaccination infrastructure was built to deliver vaccines. And by May 2021, the public and private sectors transported, stored, and injected nearly 238 million doses of vaccines into American arms all across the country. One last monumental task awaits: Getting vaccines to the hardest-to-reach individuals and those who are hesitant to be vaccinated, allowing vaccine supplies to exceed demand. William Moss, executive director of the International Vaccine Access Center, discusses the challenges that all successful vaccination campaigns eventually face.

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William Moss, Executive Director
May 3, 2021

What is the biggest concern when vaccine supplies begin to outpace demand?

One of the major problems about vaccine supplies exceeding demand is vaccine wastage.

We do not want to have areas of the nation where vaccines are just sitting in freezers not being used. There is a saying that ‘vaccines save lives.’ But it’s slightly incorrect. Vaccines don’t save lives. Vaccinations save lives. Every dose represents another person who could be protected from severe COVID-19 or, worse, death.

And that’s really the biggest concern about unvaccinated populations in the United States: Those people are going to be at high risk of getting infected and getting severe disease. If there are enough of them, they could potentially overwhelm the health care systems and we could continue to see people dying.

Do vaccines have shelf lives?

There is shelf life for vaccines and it’s actually shorter than for most medications. We’re talking about fairly short timelines on these vaccines.

Take the Pfizer vaccine, for example. Once that vaccine ships out it can be stored for up to six months if it’s kept in ultra-cold freezers. If kept in a shipper, the shelf life is 30 days. If it’s taken out and put in refrigerators, the shelf life is only five days.


‘People who don’t get vaccinated often underestimate the risk of disease and overestimate the risk of the vaccine’

Who are the hard-to-reach individuals who are causing diminishing demand?

Early in mass vaccination campaigns you quickly reach the people who have access to vaccines and the people who want to get vaccinated. We’ve made tremendous progress in vaccinating people in the United States, but there are still many people who remain to be vaccinated.

The reasons vary for why people are hesitant to get vaccinated.

  • Many people have safety concerns because they fear these vaccines were rushed and we don’t know what the long-term consequences might be.
  • There are also concerns about the efficacy of the vaccines to protect against the virus.
  • And some people just believe they’re not at high risk for getting a severe case of COVID-19.

While it’s true that younger people are at a lower risk than older people, everyone is at risk. No unvaccinated person can be sure they will not get severe disease.

People underestimate the risk of the disease to themselves and overestimate the risk of the vaccine. It’s that kind of risk calculus that leads many people to choose not to get vaccinated.

There is a small proportion in the United States who are anti-vaxxers and there is no amount of information or persuading that is going to change their minds. But there are lots of people in the United States whose decisions can be changed with appropriate messages from the right messengers.

‘There is no magical threshold that we can reach with vaccination coverage where the virus will just go away.’

What can be done to encourage more people to get vaccinated?

There’s been a fair amount of outreach conducted but much more needs to be done. It gets harder and harder to reach people as we are seeing in the United States. And this is typical of vaccination campaigns. You always have this remaining piece of the population that is hard to reach.

We need to intensify our efforts going forward to reach those who are hesitant. The efforts really need to be at very local levels. We need the influencers in people’s lives and in their communities to advocate for vaccination.

That can be health care workers, community leaders, religious leaders, church leaders. All of those leaders at the very local level need to address the specific concerns of the people in their communities. That is the best way forward.

Won’t herd immunity protect people after a certain percentage of the population is vaccinated?

Herd immunity is a useful concept that we use frequently in infectious disease epidemiology. It basically means that in a particular population the probability of an infectious individual coming into contact with a susceptible individual goes to near zero because there is an abundance of protected people in that population.

There is no doubt that as more and more people are protected you reach a point where you start driving transmission down. But that doesn’t make the virus go away completely.

There is no magical threshold that we can reach with vaccination coverage where the virus will just go away. It will continue to transmit wherever you have clusters of susceptible people, such as people who refuse to get vaccinated.

Can the lack of vaccinations in a community result in the emergence of new variants that could bypass the vaccine’s defenses?

I think the risk of new variants emerging is greater at the global level than at the national level in the United States. The big concern would be if we find variants that are able to fully escape vaccine immunity. We haven’t seen them yet. But we’ve seen variants that are more contagious and cause more severe disease.

The dire situation that we’re seeing in India, with extremely high levels of virus transmission, is an ideal setting for the emergence of new viral mutations and variants.

William Moss, Executive Director

William Moss, MD, MPH, is Executive Director of the International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health.