The concept of vaccination was first developed in the 19th century when Dr. Edward Jenner made the observation that milkmaids were immune to a deadly virus known as smallpox. He realized that most milkmaids were infected with cowpox – a less harmful virus part of the same viral family. Since the two strains are closely related, the milkmaids’ immune systems were able to tolerate and effectively target the smallpox infection. To test his theory, Jenner infected a young boy with cowpox and then exposed him to smallpox. He found that the boy was able to fight off the subsequent virus. Jenner repeatedly exposed the boy to smallpox to determine if he contracted the disease. Interestingly, the boy remained healthy and became immune. This was a breakthrough in the medical community and still stands as a turning point and cornerstone of modern medicine. As a consequence of vaccine development derived from Jenner’s work, the world was completely eradicated of smallpox in 1977 after a global vaccination campaign led by the World Health Organization (WHO).
Today, the National Institutes of Health (NIH) develop annual vaccinations against viral strains predicted to be most prevalent each season. Vaccines are critical for the health of the community as they protect those actively getting vaccinated as well as immune-deficient individuals who cannot get immunized. The rapid development of the Coronavirus Disease 2019 (COVID-19) vaccine was a major triumph in the healthcare community. As more patients were vaccinated, the more protected they and their loved ones were. This led to ‘herd immunity’ or broad protection of a population after a majority become immune from a contagious disease. Although the vaccine has been tested for efficacy, scientists are still understanding the long-term benefits and determining different contexts that optimize patient outcomes.
A recent study in Nature Communications, by Dr. Carlota Dobano and others, reported that COVID-vaccination better shapes immune response compared to infection-acquired immunity. More specifically, they found that if an individual was vaccinated and then acquired COVID-19, their immune system was better equipped compared to an individual that contracted COVID-19, recovered, and then was vaccinated. Dobano is the head of the Barcelona Institute for Global Health (ISGlobal) Malaria Immunology Group and Director of the Core Facility on Immune Response and Biomarkers. Most of her work focuses on studying the immune system in response to malaria. However, she investigates broad topics in virology and vaccinology.
Since COVID-19, most people have acquired hybrid immunity, which refers to combined immune protection from vaccination and infection. Hybrid immunity has been shown to improve immunity compared to vaccination or infection alone. Dobano and others wanted to understand whether the order in which a patient builds immunity to COVID-19 made a difference. The team analyzed a group of 357 healthcare workers that were infected with COVID-19 at different times during the pandemic. Roughly 160 of the workers were vaccinated before contracting COVID-19.
Researchers followed-up with patients over a few years and found that patients vaccinated before infection had higher antibody levels. Those that were infected before vaccination had lower antibody levels, but higher immune cell numbers. In the context of short-term immunity, scientists determined that those infected by the virus first were better protected than the pre-emptive vaccinated group because the immune cells were specific to the original COVID-19 variant. However, individuals vaccinated first and then infected by the virus acquired more diverse antibodies that could target a wide range of COVID-19 variants. This new evidence demonstrates the benefit of hybrid immunity and provides an understanding for how our immune systems work. Overall, this information can help develop better vaccines and improve patient outcomes.
Study, Nature Communications, Carlota Dobano, ISGlobal, Malaria Immunology Group, Core Facility on Immune Response and Biomarkers
