The FDA has approved an emergency use authorization for a new bivalent booster shot to aid in the fight against COVID-19. Here’s what you need to know about these new vaccines.

Q: What is a bivalent vaccine?

A: Bivalent refers to the two separate virus strains whose mRNA instructions are included in the new booster vaccine. The original, or “ancestral,” COVID strain that circulated at the beginning of the pandemic, plus the current dominant strain, the BA.4/BA.5 subvariants of Omicron. It’s not uncommon to have more than one strain of a virus incorporated into a vaccine, for instance the annual flu shot is quadrivalent, meaning it’s comprised of four different flu virus strains.

Q: Who is eligible for this new booster?

A: These vaccines can be used as a first booster (after the primary series of COVID vaccines is complete) or the second booster (as long as at least two months have passed since the first booster). Moderna’s version is available to those 18 years and older, and the Pfizer-BioNTech brand is approved for ages 12 and up.

Q: Can this be used in patients who haven’t completed a primary COVID vaccine series?

A: No, the mRNA dose in the booster vaccine is lower than what is contained in the primary vaccines. Its efficacy is only studied as a booster dose and not as a primary vaccine.

Q: Does it matter which brand of vaccine was used for the primary series?

A: It does not. Both the Moderna and Pfizer brands can be used in patients who meet age and primary vaccine requirements, regardless of which vaccines they received as their primary series or previous booster shots.

Q: Should people who had a recent COVID infection get this booster?

A: While there is no perfect answer, the prevailing wisdom currently suggests that most healthy individuals will maintain a good immune response for at least 90 days after a COVID infection, essentially functioning as a booster dose.

Q: Why is this relevant? Isn’t the pandemic just about over?

A: Unfortunately in the United States, we continue to see a death rate from COVID of about 400 people per day. While that’s much lower than the more than 4,000 daily deaths reported in the US in January of 2021, it’s still significant. With mask mandates disappearing, more relaxed standards for physical distancing, school starting, and the anticipation of colder weather on the horizon that will move people indoors, this booster is one way to limit spread and severity of disease.

Q: Does this booster shot guarantee a person won’t get COVID-19?

A: The goal of broad-reaching vaccination campaigns is to reduce what the medical community calls morbidity (the severity of sickness) and mortality (death) for large populations. COVID vaccines are no exception. The goal in vaccinating the public was to reduce the burden of serious illness and loss of life. Don’t forget that early in this pandemic, hospitals were running out of staff and space for COVID patients. Vaccination works to reduce people’s viral load, which translates into milder symptoms, lower rates of contagion, fewer community outbreaks and therefore less of an opportunity for viral mutation into a new more dangerous strain, and of course fewer deaths.

Q: Have there been human studies on the new COVID-19 boosters?

A: The data has been extrapolated from studies on mice. While that might discourage some people, keep in mind that every year a new flu vaccine is formulated using different strains of virus and it doesn’t necessitate new human trials with each new configuration. Similarly, the COVID-19 vaccine didn’t change much except for the addition of this Omicron-specific strain. Waiting to collect data from human trials would negate the attempt to protect people before the anticipated increase in COVID cases over the winter.

Q: Will this be the last booster dose?

A: It’s impossible to predict with any certainty which direction this virus will go, but the greater percentage of people in the community that have protection against contracting COVID-19, the less likely we are to see another surge of serious illness in the population.

From UH Pediatrician and PSI Medical Expert – Dr. Carly Wilbur.

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