Here's Why You Need a COVID-19 Booster Shot

Studies have shown that booster shots can help restore waning vaccine-induced immunity and provide protection against a range of COVID-19 variants.

Previous variants have been shown to reduce the effectiveness of the COVID-19 vaccines that are currently available—and future variants might as well.

While vaccine makers are exploring the possibility of variant-specific vaccines, the most effective way to stay protected against any type of COVID right now is to get a booster shot of the existing vaccines once you're eligible.

In September, the FDA granted emergency use authorization for a booster dose of the Pfizer-BioNTech vaccine, but only for select vaccine recipients. On October 20, the FDA expanded its emergency use authorization to include the Moderna and Johnson & Johnson COVID-19 booster vaccines.

Soon after, the FDA authorized a booster dose for all adults who completed their initial COVID-19 vaccine series and a Pfizer booster dose for adolescents ages 12 to 17 who completed the initial Pfizer vaccination series at least five months prior. Eligibility was then expanded to include those 5 years and older.

According to the CDC, eligible adults are able to choose any authorized COVID-19 booster. However, it is now recommended that individuals get the Pfizer or Moderna mRNA COVID-19 vaccine over the Johnson & Johnson vaccine, following concerns about blood-clotting side effects. The Johnson & Johnson shot still remains an option for those who are not able or willing to get a different vaccine.

Children and adolescents ages 5 to 17 who completed Pfizer's primary series are only eligible for the Pfizer booster.

Moderately or severely immunocompromised persons 12 and older should receive an additional dose of the mRNA vaccine 28 or more days after completing the two-dose mRNA series or the one-dose Johnson & Johnson vaccine. A first booster shot is recommended three months after receiving a third (additional) dose of the Pfizer or Moderna COVID-19 vaccine or two months after getting a second (additional) dose if the first dose was the Johnson & Johnson vaccine.

The FDA has also authorized a second mRNA booster dose for certain individuals at increased risk for severe COVID-19 illness.

The Pfizer and Johnson & Johnson boosters will be administered with the same dosage as the initial vaccine, whereas Moderna’s will be a half dose (50 micrograms).

In a statement released on April 20, Moderna's chief executive officer Stéphane Bancel said that “recent preclinical results have shown that our variant-specific booster candidates were effective against COVID-19 variants of concern, and we hope to continue to see positive results from the clinical studies.”

Moderna’s variant-specific vaccine candidates include one specifically targeted against the Beta variant and a multivalent booster (for any variant) that combines the company’s original vaccine and their shot offering protection against Beta in a single dose.

How Much of a Threat Are Variants?

The CDC created four classifications for SARS-CoV-2 variants:

• Variants being monitored (VBM): Variants that have or may pose a threat to approved or authorized medical countermeasures or have been associated with more severe disease (e.g., increased hospitalizations or deaths) or increased transmission but no longer poses a significant risk to the public.
• Variant of interest (VOI): A variant with specific genetic markers that are associated with changes to receptor binding, increased resistance to antibodies created by previous infection or vaccination, or reduced efficacy of treatments. A VOI may also have an increase in transmissibility or disease severity and potential diagnostic failures.
• Variant of concern (VOC): A variant showing increased transmissibility, more severe disease, diagnostic detection failures. or a significant reduction in neutralization by antibodies generated during previous infection or vaccination. A VOC may also show evidence of a substantial reduction in the effectiveness of one or more classes of treatment therapies.
• Variant of high consequence (VOHC): A variant with clear evidence showing that prevention and medical measures have significantly reduced effectiveness relative to previous variants.
  

Waning Immunity

Because immunity created by most vaccines wanes with time, booster shots are a necessity. It is not unusual for vaccines to require boosters in order to maintain high levels of immunity.

In an interview with CNBC, BioNTech’s co-founder and chief medical office, Ozlem Tureci, MD, said that she expects people will need to be vaccinated against SARS-CoV-2 annually because of the decrease in immunity.

During a Johns Hopkins press conference, Naor Bar-Zeev, PhD, MPH, associate professor in the department of international health and the deputy director of the International Vaccine Access Center at Johns Hopkins Bloomberg School of Public Health, pointed out that “we have to have a tetanus shot every 10 years ."

Bar-Zeev said that boosters become “all the more [important] in the current context of variants emerging. We will have the opportunity to reboost, to revaccinate, and to broaden our protection, and not only make it more long-lasting.”

During the same press conference, Durbin noted that combinations of the different existing vaccines are already being tested. In the U.K., researchers are combining mRNA vaccines (like the Moderna and Pfizer-BioNTech) with a dose of an adenovirus-based vaccine (like the Johnson & Johnson vaccine) later on as a sort of booster shot—or vice versa.

“The best way to reduce the emergence of variants and their dominance across the world is to reduce transmission of the virus in populations everywhere,” Bar-Zeev said. “And that can be achieved through high coverage with the existing vaccines. It can be achieved through maximizing the breadth of vaccine products that are available, maximizing their production, and maximizing their delivery around the world.”

Durbin added that vaccines are also important strategies for reducing the risk of severe illness and hospitalization from COVID-19, as well as deaths. “These are the critical efficacy endpoints that will make a public health impact and get us out of this pandemic,” Durbin said. “The vaccines are providing us light at the end of the tunnel, but we need to ensure global vaccine access because we will not be entirely out of the pandemic until the world is vaccinated.”

Vaccines Alone Are Not Enough

Bar-Zeev cautioned against viewing vaccines alone as being enough to turn the COVID-19 pandemic around. “Vaccines are enormously powerful tools in public health, but they’re not the only tool.”

As vaccination efforts continue, Bar-Zeev stated that “we need to maximize every tool we have at our disposal, and that does include masks and it includes distancing, and it includes public restrictions where appropriate.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.