UF Health researcher says vaccination key to protecting against the coronavirus delta variant

Kartik Cherabuddi, M.D.The coronavirus continues to mutate and evolve, and the latest in a parade of variants is causing particular worry among infectious disease specialists.

The delta variant fueled a devastating surge of cases and deaths in India, and it has proved highly transmissible while circling the globe, according to scientists. The variant has a small but rapidly increasing foothold in the United States and is already dominant in the United Kingdom, where it has delayed the lifting of COVID-19 restrictions.

Kartik Cherabuddi, M.D., an associate professor and epidemiologist in the University of Florida College of Medicine’s division of infectious diseases and global medicine, talks about the delta variant and why it concerns him more than any that has come before.   

Question: What is the delta variant and why is it worrisome?

Answer: The delta variant of the SARS-CoV-2 virus was first detected in India in October. It has now been detected in at least 80 countries, causing surges in many of them. As of June 22, it makes up more than 95% of cases in the United Kingdom, replacing the previously dominant alpha variant, and about 20% of cases in the United States in which the virus has been sequenced. The Food and Drug Administration says that U.S. cases of this variant are expected to double roughly every two weeks. This is definitely the most transmissible variant we’ve seen so far and by a wide margin. We’re seeing delta take over and expect it to become the dominant strain in the U.S. That level of transmissibility makes it very concerning.

Q: Is the delta variant more dangerous to those people who become infected?

A: Emerging data indicate delta causes more severe disease and more hospitalizations. According to a Scottish study, it causes twice the number of hospitalizations compared with alpha. For deaths, we don’t have enough data yet to know.

Q: What can we do to battle this variant?

A: Get vaccinated now. It’s as simple as that. I think we’re fortunate in this country to have several extremely effective vaccines. In our daily lives, we evaluate risk and benefit with all our activities, often subconsciously. At this time, the benefit of getting fully vaccinated is exceptionally high for adults. We want to continue to have the economy do well and continue to have the kids enjoy their summer vacations and get back to school and college in person this fall. If we want all these good things to happen, we just have to get more vaccinations done, make them more accessible, have more conversations with unvaccinated people, hear them out, and explain the benefits of a vaccine. We have to convince people to get the shot in their arms.

Q: But are the COVID-19 vaccines still effective against this variant?

A: Data from Public Health England and Scotland reveal a high degree of protection when people get both doses of the Pfizer or AstraZeneca vaccines. They’re both extremely effective at preventing symptomatic cases as well as severe disease and hospitalization. The important difference with delta is that data indicate one dose of the Pfizer vaccine provides only 33% effectiveness. So it is really important to get both doses of the Pfizer and Moderna vaccines. Moderna’s is an mRNA vaccine like Pfizer’s and is expected to offer similar levels of protection against delta, although we do not have data yet. We need to learn from what is happening in other countries. We can’t wait to ramp up vaccinations when people in our own communities start to get sick because it takes six weeks for two-dose vaccines to confer full protection. We have to do this immediately. The pandemic has not ended, especially for unvaccinated individuals.

Q: Are we particular vulnerable right now to a highly transmissible coronavirus variant?

A: We have large pockets of largely unvaccinated communities, especially in the southern United States. Introduction of this highly transmissible variant to communities with low rates of vaccinations is, unfortunately, a recipe for cases to emerge and spread rapidly. We’ve seen tough times during the pandemic. And we’ve overcome a big surge. So understandably, we have a sense of security and are using fewer protective measures. That is exactly what happened in India. After their first surge, they felt like they had overcome the virus. They lifted precautions. And then the delta variant just took over. That is why I worry. We need to get effective vaccines to the world. Our country, similar to others, can’t afford another surge. It just can’t. That is why we need to act now.

Media contact: Ken Garcia at kdgarcia@ufl.edu or 352-265-9408.


Learn more about UF Health's efforts to combat the COVID-19 pandemic at Coronavirus.UFHealth.org.

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Bill Levesque

Science Writer

Bill Levesque joined the UF Health staff in May 2017 as a science writer covering the Institute on Aging and research of faculty physicians in the College of Medicine. He...Read More