Public Health

Four Things to Know About Boosters, Variants, and Natural Immunity

September 17, 2021  • Melissa Viola

As Covid-19 cases in the US continue to emerge due to the Delta variant and resistance among some Americans to get vaccinated, the Aspen Institute’s Science & Society program convened four leading scientific and medical experts to answer some of the latest questions related to the vaccine. 

The discussion, held in partnership with and the Sabin-Aspen Vaccine Science & Policy Group, covered everything from breakthrough infections and booster shots to the chances of vaccinated people spreading the virus and developing “long COVID” symptoms Here are some takeaways:

Is naturally acquired immunity better than vaccine-acquired immunity? 

Although a Covid infection provides mucosal immunity that can protect against future infections, Dr. Akiko Iwasaki, professor of Immunobiology and Molecular, Cellular and Developmental Biology and professor of Epidemiology at the Yale School of Medicine, says that mRNA vaccines induce the same type of mucosal immune response, creating an immediate barrier that stops the spread of infection and the risk of severe illness. For those who already contracted Covid-19, Dr. Iwasaki strongly recommends getting the vaccine. “We measured antibodies from those who recovered from infection versus those who got the vaccine after recovery from infection, and there is a huge difference in the functionality of the antibodies against both the ancestral strain and the variations,” she said. “So, there is great benefit to getting the vaccine, even if you have natural immunity from Covid.”

How likely are vaccinated people to get infected with the Delta variant and spread the virus to others? 

No vaccine provides 100 percent immunity. But, according to Dr. Marion Pepper, an associate professor in the Department of Immunology at the University of Washington, vaccinated people are at much lower risk of severe illness, hospitalization, and death from Covid-19. In addition, early studies show that vaccinated people clear the virus more quickly and have immune responses that help stop its spread to others. “It does appear that vaccines are creating immune mechanisms in the nasal passages where the virus is being encountered that is not only preventing dissemination and actively killing the virus, but potentially reducing the spread because of reduced viral load,” she said.

Do vaccinated individuals need a booster to lessen the chance of breakthrough infections? 

While clinical data showed that boosters were needed for immunosuppressed individuals, Dr. Amesh Adalja, who serves as a senior scholar at the Johns Hopkins Center for Health Security, says that the health community and policymakers need to consider what will be accomplished by requiring boosters for the rest of the population. “Covid is not going anywhere and we need to get comfortable with it becoming an endemic virus,” he says. “We need to take a step back and ask ourselves if the vaccines are doing well, which they are. There may be a day that we need vaccine boosters, but the clinical data isn’t showing that it’s necessary at this point.” 

Can vaccinated individuals develop “long Covid” symptoms? 

Some Covid-19 patients recover from acute infection and continue to have persistent symptoms, yet it’s not clear what causes it and who is most at risk. While the National Institute of Health is conducting a billion-dollar study to better understand the phenomenon, Dr. Nahid Bhadelia, the founding director of the Boston University Center for Emerging Infectious Diseases Policy and Research, says that she has seen vaccinated people in post-Covid clinics who recover then have continued symptoms. Still, she says, “It’s clear that if you get vaccinated, the chances of long Covid are lower because vaccination reduces your chances of getting infected in the first place by five times.”

You can watch the entire event here.

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