麻豆传媒

Following the FDA's authorization and CDC's recommendation that all kids ages 12-17 years should receive COVID-19 booster shots, Paul Offit, MD, director of the Vaccine Education Center at Children's Hospital of Philadelphia, reflects on the U.S. vaccine strategy. Offit, who serves on the FDA's Vaccines and Related Biological Products Advisory Committee, also examines some of the missteps in communicating with the public during the pandemic.

The following is a transcript of his remarks:

Recently, what we did is that we recommended a booster dose for children between 12 and 15 years of age. What percentage of children in that age group have been fully vaccinated? About 50%. That means 50% haven't been vaccinated. Does it really make sense to focus on further protecting people who are already protected against serious illness? Or should we really devote our resources to protecting those who are completely unprotected?

If you work in a hospital, as I do, and you see children between 12 and 15 years of age coming into your hospital, they're not there because they haven't gotten a third dose, they're there because they haven't gotten any doses. I mean, this really is, at least at the hospital level, a disease for the unvaccinated, and that has to be our focus. I just feel like to some extent we've kind of given up on that, and this constant talk about boosting is in many ways a detour.

The question is, what do we want from this vaccine? If what we want from this vaccine is protection against serious illness, the current two-dose vaccine strategy for mRNA vaccines, or the two-dose strategy for the J&J [Johnson & Johnson] vaccine, offers protection against serious illness, right up to the present time for all age groups. So if that's the goal, we've reached it. If, on the other hand, the goal is to try and also protect against mild illness, which will fade over time, then you can argue for giving a booster dose, realizing that the protection against mild illness that you're getting from that booster dose will probably last for about 3 to 4 months.

I think there's been a number of miscommunications regarding these vaccines. For example, a year ago, when in December, we the FDA vaccine advisory committee, considered the Pfizer and Moderna vaccine. What you saw was 95% efficacy against mild illness. That was remarkably high. The reason it was so high is that those were 3-month studies. In other words, most participants in those studies had recently received their second dose. So neutralizing antibodies were high and therefore effectiveness against mild illness was high. There was no way that was going to last. Neutralizing antibodies had to come down and therefore protection against mild illness also had to come down.

The second miscommunication, I think, occurred on July 4 of last year when thousands of men got together and in Provincetown, Massachusetts. Roughly 80% of them were fully vaccinated. Nonetheless, 346 of those men developed COVID; 346 fully vaccinated men developed COVID. Four of those 346 went to the hospital, for a hospitalization rate of 1.2%. That's great. That's a vaccine that's working well. The other 342 had mild illness or asymptomatic infections. Those infections were called breakthrough infections, and that [term] should have never been determined that we should use that.

The term "breakthrough" implies failure. That's not a failure. What you want from these vaccines is, you want protection against severe illness. For vaccines like the influenza vaccine or the rotavirus vaccine, or the pertussis or whooping cough vaccine, you get excellent protection against moderate-to-severe disease, but not very good protection against asymptomatic or mildly symptomatic effects. That would also be true for this vaccine, and I think we inadvertently kind of damned this vaccine by holding it up to a bar that it's almost impossible to reach.

What makes Omicron difficult is, although everybody talks about how it's more contagious, it technically is really not more contagious. The contagiousness index for Delta was between 5 and 9. So what contagiousness index means is that, if it's a contagious index of 5, for example, that would mean that if I had the infection and I went about my normal day and came in contact with everybody who was susceptible, I would infect five more people.

The contagiousness index for Omicron is probably somewhere between 3 and 5. There's no evidence that it's more contagious. The problem with Omicron is that it is, to some extent, immune evasive. So even if you're vaccinated, you still might get a mild infection. If you look, for example, at Delta and Omicron in a home of unvaccinated people, it's really equally spread. However, if you look at Delta and Omicron in a home where people are vaccinated or even vaccinated and boosted, you're much more likely to still get a mild illness with Omicron, than you would have with Delta. And that's the problem with Omicron. Even people who are vaccinated can have a mild illness. And that's why you see this huge increase in cases, but don't see a proportional huge increase in hospitalizations and deaths.

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