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When Bruce Y. Lee was helping the U.S. government model delivery plans for H1N1 influenza vaccines, he came to expect one constant: The schedule would always change.

“We’d constantly have to update the models as new production numbers came out,” said Lee, a professor at CUNY Graduate School of Public Health & Health Policy, who developed computational models to guide the national response to the H1N1 flu pandemic in 2009. “That just became accepted.”


The shifting timelines are already apparent with Covid-19 vaccine distribution in the U.S. — even before the rollout starts in the coming days. The Trump administration declared in May that 300 million vaccine doses would be available by January 2021, with the first distributed in October of this year. By October, that had shifted to 100 million doses by the end of the year, according to Health and Human Services Secretary Alex Azar. Currently, the plan is for 40 million doses to be distributed in December, though some in health care are skeptical of even that prediction.

Pharmaceutical and vaccine production involves complex coordination, involving product development, manufacturing, packaging, storage, distribution, and regulatory review, and each stage can cause unexpected delays.

The manufacturing process can — and usually does — go awry at some point. “Manufacturing never goes 100%, there’s always issues and stock you have to throw out,” said Lee. “You bake a thousand cakes, you’re not going to get a thousand successful cakes.”


At every stage of production, manufacturers must test the product to show that each batch, from each different facility, is equivalent to the original. This will inevitably reveal issues that need addressing as Covid-19 vaccines are produced at unprecedented scale and speed. “Not only do we want it yesterday, but we need a lot of it yesterday,” said Thomas Denny, chief operating officer of the Duke Human Vaccine Institute. “If you try and do something quickly in your kitchen, even if you have a recipe, sometimes things go wrong.”

Every feature of the final vaccine, including buffers, glass, pipette tips, dry ice, and packaging, then comes with its own potential production issues. Pfizer recently had to cut its end-of-year supply projections for Covid-19 vaccines in half, because of delays in scaling up the raw material supply chain.

As more vaccines are rolled out, this will increase the pressure on available supplies. “You’re dealing with a limited supply chain,” said Denny. “I would not be surprised, as we get two or three vaccines being manufactured, if we see some challenges.”

Another challenge for those making predictions about vaccine availability is that manufacturing capacity is a closely guarded secret, and companies are unlikely to reveal precise details even to major buyers such as the U.S. government, said Lee.

“Vaccine manufacturers hold their production capacity pretty close to their vest because it’s a point of a negotiation.” he said. Companies want to have flexibility in their contracts so they can balance production of various drugs and vaccines. “These companies are businesses and want to maximize their revenue. They’ll continue to make other products they can sell while manufacturing their vaccine.”

“Manufacturing never goes 100% … You bake a thousand cakes, you’re not going to get a thousand successful cakes.”

Bruce Lee, professor at CUNY Graduate School of Public Health & Health Policy

Even during a medical emergency, companies won’t reveal this information, said Mark Capofari, who was director of global logistics at Merck from 1995 to 2007 and currently lectures on supply chain management at Penn State University. During the AIDS crisis, when Merck made a key treatment drug, Crixivan, production capacity wasn’t shared outside the company, he said.

Once vaccines have been fully prepared, some degree of waste is inevitable, said Lee, meaning it will take more than 80,000 vaccines to inoculate 40,000 people (each person gets two doses). Vaccine is wasted if vials are broken, stored at the wrong temperature, or opened and only a portion of the doses inside are used. Wastage of between 1% and 10% is fairly common, said Lee, and this adds unpredictability to the system.

Distributing vaccines to the right people, and at the required storage temperatures, is its own complex logistical feat. Any problems with distribution can affect manufacturing, and vice versa. “You have to match supply and demand. If you don’t, you can end up with vaccines not being used, and people not being vaccinated,” said Lee.

There’s a limited amount of storage where vaccines can be kept to one side before being sent out, meaning the entire system has to work smoothly to quickly send vaccines to locations where they can be used as soon as they’re produced. “Once you make it and pack it, you just have to move it,” said Capofari. “You only have so much time from a cold-chain perspective to get it to the clinic.”

The package delivery companies FedEx and UPS are involved in distributing Pfizer’s vaccine, and both face their own limitations, especially during the holiday season. These companies seem to be at capacity, said Capofari. “I don’t know how much you can put lift into the system now.”

Despite the many variabilities, the U.S. government is still making optimistic predictions. Earlier this week, Azar said the government is “very confident” there will be enough doses for everyone in the U.S. who wants to be vaccinated by the second quarter of 2021.

Others are less sure. “This is all the world of guesstimates. I would think you’ll see these estimates reissued and refined every couple of weeks as we go through this process,” said Denny.

Given the current information, it’s reasonable to expect that vaccine rollout in the U.S. will continue well into the third quarter of 2021, agreed Denny, Lee, and Capofari. But even this prediction is dependent on everything going to plan.

“This is a best guess with everything aligning with everything you hope it will align,” said Denny. “Rarely do we get everything to work out with that type of alignment.”

  • Reading about the history of the vaccine, as an ignorant layman, admittedly, it appears human challenge testing, which would have been a true unknown back in March 2020, would have resulted in both Pfizer and Moderna vaccines being found both safe and effective in May or June. This might not totally obviate concerns with safety, but for old folks at truly high risk, I would say approving it for them, to be taken on a voluntary basis, would have been the way to go – while truly, unreservedly, building out all the production capacity which is needed, and of course stockpiling it pending approval.
    A large scale human challenge testing program of a vaccine which was available – IN MARCH – could have lead to the public being vaccinated starting about four months back -the epidemic would be over here already.
    I hope next time the authorities will do what needs to be done. No one can assess risk of unknowns with more than guesses, but the KNOWN destruction due to lockdowns was clearly enough to justify taking risks. I think the medical establishment was just too cautious. No one wanted to be blamed if it went bad – they did not even think it would – they let the country fall apart rather than take some risks. We need to change the way CDC and FDA work, at least in these kinds of extreme situations.

  • Few questions I still have is about if covid can be catch more than once and if it can how does a vaccine prevent this? cuz doesnt a vaccine give the same result of getting over a virus?
    Will there need to be a new vaccine created after sometime like is done for flu? Also how is it tested, that people know that it’s working and how long will it work for? after the second shot when do you need the next one?
    Also are we prepared for the cause that his vaccine doesnt work as well as we hope or problem in production or distribution stopping supply for many months or if he have to stop using it cuz of side effects?
    I truly believe hope for the best but prepare for the worse.
    Its scares me that the belief that his magic bullet will make everything go back to normal including not having to worry about or act cautious.

  • Yet if you think the US isn’t approaching normal by summer you’re out of your mind. Too many people that are experts are saying “fall 2021”. I think that’s reasonable. Spring is an absolute home run. Summer is expected. Fall is the deadline. Winter is people better be losing their jobs.

  • Interesting how most articles published only discuss problems inherent in distribution but never applauds one of quickest production of a proven vaccine for a pandemic in world history be cause it does not sell eyeballs well

    • Congratulations aren’t journalism. Journalism is conveying important information to people in a way that is useful. We got a vaccine? Wonderful. Now the question is, when can I get it? Which is why information about distribution is important. No one cares about tooting horns. We care about when we can get back to normal.

    • You raise a good point. As the author points out, it’s the holiday season, and all the major shipping companies, DHL, FedEx, UPS, USPS are already to their necks in delivering seasonal packages. The US military is the obvious candidate to bypass existing delivery systems. They have the manpower, the lift capacity, and they already have a presence in all 50 states.

    • We def should not be depending on companies to do this. their job is to make money not help the country, that is the job of, the reason what government is for. The plan from the beginning should have been for a national vaccine program. with them setting up their own R&D and working with universities and companies. Then also have deal with companies to fund development and guarantee payment of dev cost and some prize incentives including patent for private production. But on the national vaccine program would ultimatly be taking charge and also from the beginning they would have created what will be needed for any vaccine with plans, procedures,infrastructure for the production and distribution and administering/application for mass vaccinations then once a canadate vaccine seems likely create the rest of the plan for the specific vaccine then if it works well enough and approved then implement the plan. Most likely the Military and national guard would be the best choice for logistics from production to administering the vaccine. Since public production of vaccine it would be distribute based on need like front line health care workers then I think should be the essential workers that cannot work from home and are the ones keeping things running. and they too should get it for free since they are prob getting mini wage and no bonus hazard pay. Then [if] the company that developed a vaccine used will be able to do what they are doing now, setup their own production and distribution and and sell it to who they want. This is such a massive effort with so many gears that there should not be the added issue of trying to make a profit and work between multiple companies that all do other things as well. Also there would be the benefit of having this vaccine program since this is only going to keep happening with more and more ppl on the planet and since vaccines normally aren’t profitable. Also the program would need to make a through report on what we will do different next time esp with containment/prevent spreading, along with handling public safety also the economy and not just how to react but what should be in place.
      Plus Im still a bit worried about side effects all medications have them and at this scale 100s of millions to billions of people so .001% of a billion is a million. I dont like giving immunity to corps. also the way money is going to flow is just so inefficient. we are going to have government pay for a bunch of stuff that they would not be paying for if did it on own and would be spending more of it on vaccines rather than medical insurance, and increased prices from each company along the chain cuz of operating cost.

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