Priorities for vaccination with the currently-available vaccines
The CDC reiterated its priority for vaccinating healthcare workers at high risk and care facility individuals first. Essential workers and those with conditions placing them at higher risk as well as those over age 65 would be in the second and third phase of the initial vaccination process.
Some reports predict 25 million people being vaccinated by the end of December and 25 million more in January.
Let’s pause for a moment and think about the information we have. With all the information flying about and the desire to get life back to the previous norm, it behooves us to take a breath and think about what we really know.
- There are still over 30 vaccine trials in progress and at least 6 other vaccine types in study. The great focus at present is on the only two that have reported early results. Both are in the process of requesting FDA approval under the EUA (Emergency Use Authorization). The UK just approved the Pfizer vaccine for use there.
- The Pfizer and Moderna vaccines are the same type of vaccine, so having similar results in both trials is reassuring about the potential for that type of vaccine.
- Let’s also look at some numbers from these two available vaccine trials. Both the Pfizer and Moderna vaccine trials had <1% of the placebo group get COVID-19. These are very small numbers. Based on the current information available, only 95 out of 22,000 contracted COVID-19 in the placebo group and 4-5 out of 22,000 in the vaccine group. That’s where the 90% effectiveness claim comes from. A question that arises from this early information is “what if 5000 people in the placebo group got COVID-19, would the vaccine group still show a 90+% prevention rate?” This is a very important question when assessing initial and early results from any study. As the vaccine trial continues and more people outside the trial get the vaccines, we will get more accurate information to better assess the true effectiveness of the vaccine.
- We still don’t know how long the protection will last.
- All that the statisticians can say at this point is that the vaccine effectively reduces the risk of getting COVID-19 and that the outcomes of the trials so far are not likely to be due to chance.
- The federal government has purchased a total of 200 million vaccines from both companies. That means that this vaccine purchase will be available for 100 million individuals since each are a series of two injections. That’s a lot of folks but not enough.
- Although both Pfizer and Moderna say that distribution would not be limited because of the low temperature requirements of both vaccines, it is likely that each will be distributed to a local entity like the Colorado Department of Health and Environment to then be distributed locally. How that will happen has yet to be determined.
- There has been little discussion about vaccine availability to those in more rural areas. This issue has yet to be adequately addressed.
- The current vaccine distribution is based on what has been pre-emptively purchased by the federal government. This does not preclude a distribution program outside the government-sponsored program. That would likely come later after the initial orders are filled.
- More vaccines are on the way, and I am optimistic there will be other equally effective vaccines coming down the pipeline. The only question is when.
The AstraZeneca vaccine initially reported a 70% effectiveness rate. Unfortunately, it seems there was a bit of a snafu about some people getting an incorrect dose. So it is possible the vaccine is more effective, but they may have to repeat their study to clear up their initial results and get through the FDA.
What is an effective vaccine?
We normally look for a vaccine that provides 90+% effectiveness with the disease it is intended to affect.
Effectiveness though has two definitions in the case of vaccine effectiveness.
- It can be defined as preventing the disease. This is the preferred outcome. This is true with the Pneumovax-23 and the new Shingrix vaccine. They prevent the intended disease 90+% of the time.
- It can also be defined as prevention of the disease or mitigation of its symptoms. A good example is the original shingles vaccine, Zostavax, that was reported as 90% effective. The reality was that the vaccine prevented the illness about 35% of the time and another 55% of people still got shingles, but it was a very mild case.
It is important to always ask what “effectiveness” means when someone says “a vaccine is 90+% effective”. In the case of the two available vaccine trials, the reporting of 90+% effectiveness means prevention of COVID-19.
In this time of the coronavirus pandemic, the FDA has defined a vaccine trial as “successful” if it shows a 50% reduction in cases of COVID-19.
This 50% number is unacceptably low for usefulness in the current pandemic. I would not consider giving my patients a vaccine that resulted in half them not receiving a benefit. A vaccine that shows 70% effectiveness at reducing COVID-19 would still mean that 30% of vaccinated individuals could still get COVID-19.
The goal is clearly to prevent COVID-19, and those with a 90+% prevention rate would clearly be preferred to those with a 50% or 70% prevention rate.
