Health Features

Asked & Answered: Vaccine Update

This year, it’s fair to say that we’ve been thinking more about vaccines than usual. With August being National Immunization Awareness Month, we reached out to Dr. Sharon Frey, the clinical director of Saint Louis University’s Center for Vaccine Development, with some questions about COVID-19 vaccines and the upcoming flu season.

How long are COVID-19 vaccines effective?
We have data that shows the vaccines protect against severe infection for at least eight or nine months. They aren’t going to be 100% effective. People can still get mild or moderate causes, but there is less of a chance that hospitalization will be required. When we talk about vaccine efficacy, we’re looking at antibody protection. As time goes by, the antibody response will wane. We need to be patient and see what that means for COVID.

Do the vaccines work against variants?
They have been shown to be effective against the variants they’ve been tested against, and it’s important that people get vaccinated to stop the creation of new ones. Variants are mutations of the virus that vary from the original strain. The less a virus can spread, the less likely it is able to mutate.

Is it likely that a booster will be required?
It wouldn’t be unreasonable to think that at some point we may need a booster if the strain cicularating varies enough from the one we developed the vaccine against. For example, with the flu, the virus mutates easily, so there are several variants spreading every flu season. Each year, we pick the four virus strains that are most likely to circulate and develop the vaccine against those. Right now, the COVID vaccines are highly effective, so the question is how long do we wait until we recommend booster injections? It will definitely improve the antibody response, but that doesn’t mean a person’s existing response isn’t effective.

At the end of July, around half of the population was fully vaccinated. What does that mean for herd immunity?
We can’t have herd immunity at 50%. It occurs when enough people are vaccinated that it interrupts transmission of the virus, making it impossible for it to survive. People also can develop antibodies that disrupt the process by being infected. However, COVID-19 has killed many people; we don’t want more getting sick. It’s much preferable to be protected via vaccination and not infection.

Are there any concerns with students returning to school and flu season approaching?
Kids, like all people, are social. They play together, and if one person becomes infected, they can easily transmit it. We’re already seeing a higher incidence of other respiratory infections because people are wearing masks less. With flu, COVID and other viruses circulating this winter, it will be hard to tell what people are sick with, which will make it difficult to determine who needs to stay at home if they are ill. People should strongly consider receiving their flu and COVID vaccines.

When is the best time to get a flu shot?
We tell people to wait until late September to get vaccinated. In St. Louis, flu season usually doesn’t start until around October. However, this year is not going to be typical. We have no idea what is going to happen with the flu. It may come back harder, but we just can’t predict what the situation will be.

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