Explainer: Who should get the COVID-19 booster shot?

(Tiếng Việt)

The Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have authorized a third dose of the Pfizer COVID-19 vaccines, which were initially two-dose vaccines. Both federal agencies said that people who are over the age of 65, have weakened immune systems, or have a chronic illness (such as obesity or high blood pressure) should receive a third dose of the vaccine. The FDA also recommended that people who work in jobs where they interact with the public also get a booster shot: teachers, health care workers, or grocery store workers, among other jobs.

The U.S. Department of Health & Human Services have announced they will prepare to offer booster shots of the COVID-19 vaccines for those who are eligible beginning the week of Sept. 20, 2021. 

Why is a booster shot necessary? Should you get the third dose of the COVID-19 vaccine? 

Why do immunocompromised people need the COVID-19 booster? 

The CDC has recommended that people who are immunocompromised, people with weakened immune systems due to a medical condition, should receive a third dose of the Pfizer or Moderna COVID-19 vaccines. CDC studies show that even after vaccination, people with weak immune systems still have fewer antibodies to fight against the COVID-19 variants, putting them at higher risk for being infected with COVID-19. 

The CDC made that recommendation after reviewing data that showed that among people who are vaccinated against COVID-19, and who are subsequently hospitalized because of a COVID-19 infection—a majority of those “breakthrough” cases were immunocompromised people. The data shows that 44% of people who are vaccinated but still end up in the hospital are immunocompromised people. 

In other words, the initial COVID-19 vaccines are not as effective in protecting immunocompromised people from hospitalization and death. 

The CDC also analyzed data which showed that among immunocompromised people who did not develop enough antibodies against COVID-19 after the initial vaccination, 33% to 50% developed an antibody response after receiving the third dose of the vaccine.

The CDC advises immunocompromised people consult their healthcare provider about their medical condition and whether getting an additional dose is appropriate for them.

Who else can get a COVID-19 booster shot?

Currently, the only people eligible to receive a third COVID-19 shot are those who received the Pfizer vaccine and who are over the age of 65, have weakened immune systems or a chronic illness such as obesity or high blood pressure, and work in a profession where there is “high risk of exposure to Covid.” According to US Surgeon General Dr. Vivek Murthy, at a White House press briefing, “If you are six months out from your last dose of the Pfizer vaccine, you are eligible for a booster if you fall into one of three high risk groups.”

The U.S. Department of Health & Human Services has announced that the U.S. will offer booster shots at no charge beginning the week of Sept. 20, 2021. The government will also directly distribute booster shots to nursing home facilities. Boosters will also be available at pharmacies, doctors’ offices, and mass vaccination sites.

CDC director Dr. Rochelle Walensky said that the CDC is continuing to monitor health data and will make recommendations if other populations need the booster shot, including people who received the Moderna and Johnson & Johnson vaccine: “CDC will continue to monitor the safety and effectiveness of COVID-19 vaccines to ensure appropriate recommendations to keep all Americans safe.”

Why are booster shots necessary?

Eight top U.S. public officials released a joint statement saying that based on current data, the protection provided by the COVID-19 vaccines “begins to decrease over time following the initial doses of vaccination.” And because the Delta variant causes more infections and spreads faster than earlier forms of the COVID-19 virus, U.S. public health officials say that the current vaccines are not as effective in protecting against those variants, which is why they’re recommending a booster shot. 

With efforts to distribute booster shots currently underway, the U.S. is following the lead of Israel, who started administering third shots to seniors over 60 in July. According to a study released by the Israeli government, the booster shots have effectively curtailed the Delta variant of COVID-19. 

Does this mean that the current COVID-19 vaccines are not working?

According to the CDC, the answer is no. The current COVID vaccines are ​​”working very well to prevent severe illness, hospitalization, and death, even against the widely circulating Delta variant.” 

Yale Medicine, which is affiliated with Yale University, said that vaccine efficacy waning over time is natural and that “protection [still] remains high for six months.”

Dr. Albert Shaw, a Yale Medicine infectious disease specialist, said that while a booster shot is a good strategy for maintaining high protection against COVID-19, another important strategy is to encourage those who are unvaccinated to become vaccinated. More people becoming vaccinated will prevent the spread of COVID-19 and prevent new, more infectious variants of COVID-19 from emerging. “Ultimately, [vaccinations] is what needs to be done to end the pandemic,” said Shaw.

To make an appointment to get your vaccine, visit

Viet Fact Check has partnered with a number of community and health organizations to educate the Vietnamese-American community on the COVID-19 vaccine. The project is supported by: Progressive Vietnamese American Organization (PIVOT), Asian Health Services (AHS), the California Healthy Nail Salon Collaborative, Union of North American Vietnamese American Students (UNAVSA), Southeast Asian Resource Action Center (SEARAC), Asian American Research Center on Health (ARCH) and the Association of Asian Pacific Community Health Organizations (AAPCHO).

This article is supported by the Centers for Disease Control and Prevention of the U.S. Department of Health and Human Services (HHS) as part of a financial assistance award totaling $3,300,000 with 40% funded by CDC/HHS. The contents are those of the author(s) and do not necessarily represent the official views of, nor an endorsement, by CDC/HHS, or the U.S. Government.