According to the United States news outlets, the Food and Drug Administration (FDA) will soon allow American nationals to receive coronavirus vaccine booster shots different from their original shot. In addition, the federal agency seems possible to allow nationals to switch vaccines when choosing a booster shot. That approval, which may come this week, is the latest move in a long-running discussion over whether a mix and match strategy helps protect Americans from the COVID-19.
“Clinically, all the data says that mixing and matching is fine. There’s no downside.”@ashishkjha, dean of Brown University’s School of Public Health, joins us to talk about the FDA reportedly planning to allow Americans to mix and match their COVID-19 boosters. pic.twitter.com/jgVpQxrrAg
— TODAY (@TODAYshow) October 19, 2021
Here below, we will discuss answers to some questions about mixing and matching booster doses.
What is the difference in mix and match strategy?
Vaccinations usually consist of two or more shots of the same vaccine. For example, the Moderna vaccine is administered in two identical doses of mRNA, separated by four weeks. A double dose of vaccine can create much more protection against the virus than a single shot. Moreover, the initial dose causes the B cells of the immune system to make antibodies against a pathogen.
Other immune cells, such as T cells, develop the ability to diagnose and kill infected cells. The second dose strengthens that response. The T cells and B cells are dedicated to combating coronavirus multiply into much more significant numbers. Furthermore, they develop more powerful attackers against the enemy. During the last some years, some vaccine researcher companies experimented with a switch from one vaccine to another from the second shot. Medically the strategy called a heterologous prime-boost.
The outbreak stimulated more research into this possibility. One of the first approved heterologous prime-boost vaccines for any disease or virus is the Sputnik V vaccine, developed last year to prevent coronavirus. Additionally, it uses two different adenoviruses to deliver COVID-19 proteins, which the human immune system then attacks. The initial shot contains an adenovirus named Ad5, and the second shot has another named Ad26.
Why might a mix and match strategy be better to combat the virus?
Scientists long suspected that heterologous prime-boosts occasionally work better than two identical shots. In addition, the designers of the Sputnik V vaccine were concerned that the initial shot of Ad5 would create disease antibodies not just against the COVID-19 proteins it delivered but also against Ad5 itself. As a result, the second shot of Ad5 might beat by immune systems of people before it could lift protection against coronavirus.
Similarly, studies of experimental HIV vaccines suggested that mixing vaccines could make an extensive and more powerful response than several shots of a single vaccine. Various types of vaccines stimulate the immune system in different ways. Besides, switching between two vaccines might give individuals the best of both worlds. The pandemic gave health researchers new opportunities to test that idea.
What about the coronavirus vaccine booster?
Vaccines against some diseases need over two doses in a primary series to reach the maximum best protection. In other cases, another shot, after the primary series, required to reestablish weakening immunity. Over the summer, both Pfizer-BioNTech and Moderna vaccines started showing some loss of effectiveness against infection, though they both remained strong against hospitalization and death. However, the Biden government started a push for booster shots to restore the immune responses of Americans.
BioNTech and Pfizer ran trails of vaccine boosters, while Moderna ran its own researches. The FDA approved a booster shot of Pfizer-BioNTech last month for some specific groups of Americans who received two shots earlier this year. Furthermore, the agency expected to do the same for Moderna booster this week.