COVID vaccines and relative effectiveness: Yahoo News Explains

On Thursday, Johnson & Johnson submitted it’s COVID-19 vaccine for Emergency Use Authorization by the U.S. Food and Drug Administration. If greenlit by the Food and Drug Administration, it could be the nation’s third COVID vaccine producer, joining Pfizer and Moderna. Johnson & Johnson said last week that its one-dose vaccine has an overall 66% efficacy rate, not as high as Pfizer or Moderna’s two-dose vaccines with nearly 95% efficacy. Yahoo News Medical Contributor Dr. Kavita Patel explains why all of the top coronavirus vaccine manufacturers with clinical trials are a success across the board.

Video transcript

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DR. KAVITA PATEL: The ultimate goal of any vaccine is to really prevent the worst-case outcomes for that disease, in this case death and hospitalizations. And we've achieved that. So efficacy, or effectiveness, really refer to how this vaccine, or a vaccine, can actually reduce the risk relative to a population that has not received the vaccines. But a better way to think about it is really 95% effectiveness, or efficacy, translates to a reduction of the risk by 95%, compared to people who do not get the vaccine.

We know that both Pfizer and Moderna reported out a 94% to 95% efficacy and interestingly enough, about 100% prevention of death, which is actually something we've seen across all the manufacturers. Pfizer and Moderna required two doses. At the time that Pfizer and Moderna conducted their trials, there were not as many or any evidence of these variants which we're now concerned about. And Moderna and Pfizer have been testing the currently available vaccines against these variants. There is a reduction in the antibody response with Moderna, but it still achieves what we look for with a vaccine, which is a neutralizing antibody response, meaning it's good enough, but not as good as it is against some of the other variants.

Johnson & Johnson in a press release recently reported that they had an overall efficacy of 66%, when they took into account the fact that they were in clinical trials with the evidence of these variants in their trial participants. So that reduced efficacy is probably driven from the effect of these variants. So they are not apples and apples or apples and oranges.

But the most important statistic is, once again, we saw 100% prevention of death and an 85% reduction of risk, or 85% efficacy, of severe disease-- so all in all, really incredible, strong news for a vaccine, which is one shot. Johnson & Johnson is one shot, and you're done.

ANTHONY FAUCI: I don't think we should be put aback by the fact that there was a difference in the initial number of any kind of efficacy, because there's a lot more to protection than just preventing from getting infected. You want to prevent people from getting seriously ill. You want to prevent them from getting into the hospital. And you want to prevent them from dying.

KAVITA PATEL: COVID is not the flu, obviously. But in terms of vaccines, we use a yearly flu vaccine, which can vary in efficacy, in some years as low as 10% and in great years, as high as 60% to 65%. So again, I think it's important to look at efficacy from what it does. It reduces the risk. And even reducing the risk by 50% is incredible when we have thousands of deaths a day, millions of cases so far. Remember, the Food and Drug Administration was setting a bar of 50%. So we achieved way above that, which is why I think we're all expecting what seems like near perfection. But these are incredibly good across-the-board efficacy rates, and we should be happy to take any of these vaccines.