Do vaccines protect against the COVID Delta variant, are booster shots needed, and can vaccinated people get symptoms?

• Vaccines protect against the Delta variant, but questions remain over how long they remain effective.

• Most fully vaccinated people who get the COVID Delta variant are asymptomatic, according to world health officials.

• Data shows states with low vaccination rates are seeing the most Delta variant cases.

With the Delta variant becoming the most dominant strain of COVID-19 in the U.S., Americans want to know if vaccinated people are protected from the easily transmissible variant.

There have been reports about vaccinated people traveling on vacation and contracting COVID-19. At a wedding near Houston, TX, a COVID-19 outbreak involving the Delta variant infected six fully vaccinated individuals.

So as positivity rates vary by state, new questions emerge: Will you be required to get a booster shot to stave off the Delta variant? And can you get sick from the Delta variant if you’re fully vaccinated?

Here are ansers to three timely questions.

Do vaccines protect against the Delta variant?

COVID-19 vaccines are effective against multiple variants of COVID-19, including the Delta variant, according to research.

Two doses of AstraZeneca or the Pfizer vaccine were found to be 60% and 88% effective, respectively, while Johnson & Johnson and Moderna also said their vaccines are effective against the Delta variant.

Do I need a booster shot to protect against the Delta variant?

Health experts say no, but we don’t really know right now.

While the big three vaccines available in the US — Moderna, Pfizer, and Johnson & Johnson — all show signs of protection against the Delta variant, it’s unknown how long the protection lasts.

Speaking to USA Today, Dr. Paul Offit of the Children’s Hospital in Philadelphia, said he’s “not worried yet” about the vaccinated needing a booster shot because if the vaccines weren’t protective, more vaccinated people would be getting sick from the variant.

Pfizer recently said it plans to seek authorization for a booster shot in the US, saying that its vaccines could become less effective in six to 12 months after someone receives the two shots.

However, the Centers for Disease Control (CDC) and Prevention and the Food and Drug Administration (FDA) said that they will make a decision as to whether fully vaccinated people will need an additional shot.

“Americans who have been fully vaccinated do not need a booster shot at this time,” acccording to a joint statement via the New York Times. “We are prepared for booster doses if and when the science demonstrates that they are needed.”

Are fully vaccinated people experiencing symptoms from the Delta variant?

Global health officials said those who have received shots against COVID-19 can still get infected by the Delta variant, but the vaccines have protected most from getting severely ill.

Dr. Soumya Swaminathan, the World Health Organization’s chief scientist, said at a press briefing on Monday that the “majority of [Delta variant infections] are mild or asymptomatic” for the vaccinated.

Brandon Brown, PhD, an associate professor in the School of Medicine at the University of California, Riverside, told Healthline that fully vaccinated people can still transmit the Delta variant to others due to how transmissible the strain is.

“Infections and hospitalizations may continue to rise,” he said, “and it is possible for fully vaccinated people to transmit the virus to others who are unvaccinated.”

Fully vaccinated people are much less likely to contract an infection, which greatly reduces their ability to transmit the virus.

But scientists are still trying to determine exactly how often fully vaccinated people who contract an infection transmit the virus to others.

Where is the Delta variant most prevalent right now?

Nearly every state has seen a new surge in COVID-19 cases over the past week, according to new data. However, the Delta variant, which first appeared in India, hit stateside in March and quickly became the most dominant strain in less than three months.

CNN reported that states with low vaccination numbers had COVID-19 case rates three times higher last weeks compared to other states where people are fully vaccinated. 

Fewer than 35% of residents in Alabama, Arkansas, and Mississippi are fully vaccinated, making them the only states with numbers under that plateau. Those states were among the 10 worst in the country for daily cases last week, according to CNN.

Data released by the CDC last week showed the Delta variant appears to be most dominant in the Midwest and the West, two areas that are struggling with vaccination efforts. Iowa, Kansas, Missouri, and Nebraska made up more than 80% of cases last week.