Posted 10:17 a.m. Tuesday, Aug. 10, 2021

Student holds a sticker reading "I got my COVID-19 vaccine."

Immunology expert discusses vaccine efficacy, future boosters and concerns about the Delta variant

Just as Americans were beginning to breathe a maskless sigh of relief, feeling a return to some pre-pandemic modes of meeting, working and playing, the Delta variant of the coronavirus has surged across the country. This highly-contagious strain of the coronavirus that began in India in December is now the dominant strain in the U.S. A growing number of cases has created a heightened urgency to increase vaccine coverage across the country and generated more questions among the vaccinated and unvaccinated alike.  

Peter Wilker, associate professor of microbiology at UWL, has a doctoral degree in immunology and a master’s degree in public health epidemiology. Over the last 12 years, he has been studying influenza viruses. Here he addresses primary questions about this strain, the effectiveness of vaccines and more. 

What is the Delta variant?  

The Delta variant is one particular version of coronavirus. It is now the dominant strain in the U.S. The reason we are concerned about the Delta variant is that this particular version of the virus has some mutations that make it much more contagious. It can spread through communities much more efficiently than the original coronavirus strain. It is a concern because we still have a large number of people out in the community who have not been vaccinated, as well as children under 12 who cannot be vaccinated. 

Is the vaccine effective against the Delta variant?  

The Delta variant is much more infectious compared to original coronavirus strains. If you are vaccinated, I have good news for you. The vaccines have been shown to be very protective against the Delta variant. They prevent infections, severe disease, hospitalization and death. If you are unvaccinated, the Delta variant poses a very significant threat because of how easily it can be transmitted from person to person.    

What are the chances you can get COVID-19 after being fully vaccinated?  

It is important to recognize that no vaccine is 100 % protective. That said, break through infections for this coronavirus remain pretty rare. By breakthrough infections, I mean a coronavirus infection in someone who has been fully vaccinated. It is hard to know how many fully-vaccinated people experience coronavirus infections because the vaccines are doing a good job. They give your immune system a head start on fighting that infection. That means even if you suffer a breakthrough infection, it is typically very mild or even asymptomatic. 

Are there any benefits to not getting vaccinated?  

The best way to address this question is to weigh the risks associated with the vaccines against the risks of not being vaccinated. All three vaccines that are licensed for use in the U.S. have been thoroughly tested. They have been shown to be safe and very effective at preventing severe COVID-19. Severe adverse reactions from vaccines are extremely rare. In contrast, there is a much higher risk of contracting severe COVID –19 disease and long-lasting symptoms in unvaccinated people. The benefits of being vaccinated far outweigh the risks.  

Am I immune if I’ve already had COVID-19?  

If you’ve had a documented case of COVID-19, you have probably acquired some protective immunity from a prior infection; however, we are not sure if that level of immunity from the prior infection will be sufficient to protect you from being reinfected long term.  In contrast, vaccines have shown to prevent severe infection and disease. For that reason, we recommend people who have had a prior infection with COVID-19 still receive the full course of COVID-19 vaccines to boost their immunity. 

Is a booster likely coming for the Delta variant? 

Data show the current vaccines are very effective against the Delta variant. That said there may be a need for booster vaccinations down the road as new virus variants emerge. But right now our primary need is to vaccinate those who, up to this point, have chosen to remain unvaccinated. Vaccinating the unvaccinated will go a lot further than revaccinating people who have already been vaccinated. 

Do you predict more virus variants in the future?  

Yes, I do. As a virus continues to circulate, new variant strains will emerge. This is because coronaviruses make relatively frequent mistakes when copying their genome during an infection. Those mistakes or mutations occasionally confer some new properties to the virus and give it an advantage. That is what is seen with the increased infectivity of the Delta variant.  It is a very similar problem that we have when we deal with influenza. Influenza is a virus that also accumulates mutations, generating variants. Because of those new variants, we have to update the influenza vaccine and be revaccinated annually. 

Are there other ways to boost the immune system?  

The idea of boosting the immune system is a very attractive idea, but really our ability to do that has remained pretty elusive. I know you can go to the pharmacy or grocery store and there is no shortage of products that claim to be immune system enhancers or boosters. But there is actually very little scientific evidence to support that. In general healthy living strategies make a lot of sense to me, and they come with a lot of other health benefits as well.  

Why would you wear a mask if you’ve been vaccinated? 

Vaccines aren’t perfect. They don’t work like a magic forcefield. So, if you are a person spending time indoors with unvaccinated people or with people who you don’t know their vaccination status, you may wear a mask for additional protection. Another reason people choose to wear masks is if they have vaccinated loved ones who would suffer severe consequences if they were infected with the coronavirus. A mask is a way to help prevent bringing the virus home and to your susceptible loved ones.