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Trump's Covid-19 vaccine timeline is missing key context about logistics of herd immunity

Creating a safe vaccine is just one step. We then need to distribute it to a huge number of Americans.
Image: President Donald Trump tours the Center for Disease Control after a coronavirus briefing in Atlanta, Ga., on March 6, 2020.
President Donald Trump tours the Centers for Disease Control and Prevention after a coronavirus briefing in Atlanta on March 6, 2020.Tom Brenner / Reuters

With Covid-19 continuing to ravage communities, Americans are anxious to discover a vaccine. This week, President Donald Trump claimed we could have a vaccine as early as mid-October — something directly contradicted by Centers for Disease Control and Prevention head Robert Redfield, who predicted we might see something by the end of the year, if that. On Friday, Trump predicted more than 100 million doses of a vaccine will be available by the end of the year.

There’s an obvious political reason why Trump — or other lawmakers — might wish to get our hopes up about a vaccine before the November election.

There’s an obvious political reason why Trump — or other lawmakers — might wish to get our hopes up about a vaccine before the November election. But based on my 35 years spent developing drugs for serious medical conditions, including AIDS and sepsis, this is unlikely to happen as quickly as some politicians have told us.

Importantly, creating the vaccine is just one step. We then need to distribute it. Because while vaccinating everyone is impossible, vaccinating enough people to create a protective herd immunity is not. This is really the key when we talk about returning to “normal.” You’re not hearing much about that from the president because it’s easier to just allude to a magical vaccination that will immediately fix everything. And there is no magical solution to this problem.

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Until now, the federal government has eschewed a leadership role in pandemic response. The crew that tried to derail CDC’s venerable Morbidity and Mortality Weekly Report and accused the CDC of sedition has not positioned itself to be a credible force for public health. An administration that has eliminated nonpartisan careerists throughout government in favor of politically favored but professionally naive opportunists is unlikely to pull off the most significant logistical challenge ever undertaken by the government within our borders.

Vaccines are generally safe and effective because to be approved, they must go through rigorous testing. This helps keep people safer — and the drug companies that make those vaccines profitable.

Drug companies don’t make money by testing vaccines, but by selling them. When a drug company says vaccines take years to develop, that’s because the company wants to get the vaccine right. Some vaccines may make the disease worse, at least in some people, so proper testing is essential to protect public health. If we cut corners on testing, the risk goes up that a vaccine may be unsafe or ineffective.

But before we reach that herd immunity, we will have to clear four hurdles: clinical trials, regulatory review, filling the supply chain and getting enough people to get vaccinated.

To adequately test a vaccine, the sample population must be large enough, which in the case of Covid-19 is about 30,000 people, which may seem like a lot. However, the more people you study, the faster you can get to an answer. Since Covid-19 began in the United States in earnest in March, more than 6 million people have been infected in a nation with 330 million people. That’s about 2 percent of the U.S. population in six months. If we apply this to a study of 30,000 people, that would be about 45 cases per month in the control group and hopefully half of that with the vaccine.

That’s not a lot of people to study.

Still, Pfizer seems to have done a good job, with over 29,000 people enrolled in its study. So far, most of the possible side effects have been mild. This is encouraging and supports the CEO’s statement that it could have the results of interim analysis in late October. Moderna is not far behind. However, we must keep in mind that an early report does not guarantee there will be enough data to support even an emergency Food and Drug Administration authorization, much less full approval.

For the sake of discussion, let’s imagine there is a positive result announced in late October and the vaccine not only decreases viral infections, but also reduces clinical symptoms like shortness of breath and fever.

While I have great respect for the scientific integrity of Pfizer’s research and development group, terrible things have happened when a federal agency took a manufacturer’s word that its product was safe.

Therefore, the FDA will need to get the relevant vaccine trial data (this will take time) and conduct its independent review. One month to review this volume of data would be record-breaking. However, given the novelty of the product (no mRNA vaccine has ever been approved) and the shortcuts being taken for Operation Warp Speed, an independent advisory committee of medical and statistical experts will also need to review the data. If all give up their holidays, a recommendation could be made at the end of December. However, if there are any hold-ups at all, there will be a further delay.

Then the supply chain needs to be filled and the drug delivered to the professionals who will administer it.

It is reported that Pfizer’s product may require ultra-cold storage at minus 94 degrees Fahrenheit. This type of specialized storage is not available in your typical doctor’s office; it is found in universities and research centers. If the vaccine that’s first out of the gate does require this kind of storage, the logistics of distribution will be daunting. Even if the military is mobilized to distribute the vaccine, the hurdles will be formidable. Suppose a second vaccine is approved rapidly. In that case, the complexity will multiply, since the vaccines are not interchangeable: You must have the same vaccine for both shots.

And how many people will need to be vaccinated? An optimistic model says 43 percent will need to have potent antibodies to achieve herd immunity, and the administration claims it will do it in one year. That is 142 million people. But if the vaccine is only 50 percent effective, it could take many more people to reach immunity. Currently, we can’t get that many people to wear a mask. And an NBC News poll showed that more than half of Americans are still wary of a Covid-19 vaccine.

Nonetheless, if the federal government steps up to the job, pharmaceutical companies and the military fill the supply chain and vaccine supply is unlimited and available at every hospital with an ultra-cold freezer, each of the approximately 7,000 hospitals in the U.S. will need to vaccinate 20,000 people, two times. That will be 40,000 visits or nearly 800 per week, on top of continuing to provide their routine care.

If this overwhelming task can be accomplished, then there will only be three things left to worry about: potential rare but serious side effects that were not discovered during testing, the possibility of vaccine-enhanced infections or respiratory disease and the ever-present risk of mutation that could cause us to need to do the whole thing over again.