COVID-19: Third Dose Vaccines

There is a lot of confusion about the role of a third vaccine, or extra doses, for Americans and West Virginians and the potency of vaccines given late 2020 or early 2021.

First of all, let me try to be clear on what we know, what we believe and what we do not know about this issue.

What we know

We know that vaccines are the treatment that saves lives, amazingly well and remarkably consistent. That is right – I said treatment. I was asked why we are not working on more treatments for COVID-19, and I said, “We have a treatment that, two weeks after the last dose, gives over 90% protection from becoming infected from COVID-19 and over 95% effective in preventing severe disease.”

That is exactly what the mRNA vaccines from Pfizer and Moderna do.

In this way, they are among the most effective vaccines ever made. Like gifts to protect us. But only if we use them. That is what is so tragic today.

We have the answer to the most important problem that is acutely affecting our entire world – COVID-19.

We know that vaccinations are the cornerstone of our treatment strategy and that the unvaccinated are at much higher risk of severe consequences of COVID-19 than fully vaccinated West Virginians and Americans, irrespective of how long it has been since your vaccination.

We also know from real-world data coming largely from Israel and, to a lesser degree, from the United Kingdom, we know that six months or more after the second vaccination, there is a loss of some potency of the vaccines.

Because Israel partnered with Pfizer and has reported step-by-step experiences, this is where I am learning about this part of what we know.

People that were vaccinated over six months previously were protected less well from developing symptomatic infection. To be clear, this is not hospitalization, ICU admission or death. It is becoming infected with COVID-19 two weeks or more after completing the vaccines. This protection went from over 90% to 37-46% overall. Importantly, for those older than 60 and more than six months from their second vaccine, their protection was only 16%.

This data from Israel is focused on Pfizer’s vaccine. Similarly, Moderna is now coming out with their data, which shows a peak in antibody production at 43 days. Recent data published in the Morbidity and Mortality Weekly Report from Centers for Disease Control shows that several studies (from the Mayo Clinic, state of New York and from a group of nursing homes) that the potency of Pfizer and perhaps to a lesser degree, Moderna, is allowing more breakthrough infections.

My last blog talked about the data in Provincetown, Massachusetts, where 75% of approximately 1,000 people who were infected with COVID-19 during a July 4 celebration were fully vaccinated. Also, as previously communicated, only four of these people with breakthrough infection needed to be hospitalized.

This data reinforces that in the United States, being fully vaccinated is still very protective against severe illness from COVID-19.

However, let’s explore what has progressed in Israel, as a warning to us.

With the Delta variant now dominant in Israel, despite having almost 70% of their total population vaccinated, Israel has seen their new cases of COVID-19 rise rapidly. Over the last two months, their active infections went from around 200 to now over 50,000.

Moreover, they are tracking severely ill people in the hospital. On August 15, the number of people tracked was 514. This group is growing, as evidenced by a 38% increase in these severely ill people over four days prior. What is concerning is that a reported 20-58% of this severely ill population are fully vaccinated (conflicting numbers from two reports). Most of these severely ill (hospitalized) vaccine breakthrough cases are in those who are over age 60 and have other health challenges.

Israel decided to offer third dose vaccinations to all their elders with vaccination five months before or more. They initially offered this booster to those over age 50 and now to those over age 40, as well.

Importantly, Israel reports that in their citizens over age 60 who had the third dose shot a week ago or more, there is an 86% reduction in severe illness. This data suggests that in their most highly vulnerable group, third vaccine doses work much more quickly than the two-week period we saw with the first two shots.

Data from Israel is applicable to us. We know that we are all deeply connected in our world, and to protect each of us, we need to protect all in the world. This should be our mission – to protect West Virginians and Americans – but to be active and effective world citizens, too.

What we believe

We believe that third doses may induce a longer-lasting antibody response than the first two doses.

There is data suggesting the most powerful dosing schedule for maximal and prolonged antibody production may be two months between shots. In this scenario, perhaps the first two shots actually functioned as priming doses and this third “booster” will give a more prolonged benefit.


We also believe that seeing breakthrough infections are the first step to seeing more severe infections in some of our most compromised citizens who were vaccinated the earliest.

We believe that third doses will protect these people and all that have been vaccinated in the past from the much more infectious Delta variant.

What we don’t know

We don’t know if the third dose will help reverse symptoms of long COVID-19 that may have come in those with vaccine breakthrough infections, although some will likely benefit.

We don’t know if other more powerful variants than the Delta variant will come, necessitating additional strategies. But we do know that the fewer fully vaccinated people we have, the more the virus can mutate and new variants/strains will form.

We don’t know how many more of us will decide to be fully vaccinated, but I hope that it is all eligible people. Too many deaths and too much suffering have occurred that is treatable by full vaccination.

We don’t know the future.

But we do know that staying together, loving each other, protecting each other, caring about and for each other is always the right answer.

Stay strong and stay together, West Virginia.

Show why we remain Almost Heaven.

Clay Marsh, MD
West Virginia COVID-19 Czar
Vice President and Executive Dean, WVU Health Sciences