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Home >Science >Health >Do you need a Covid-19 vaccine booster shot? What to know

US health regulators will likely approve a Covid-19 booster shot for vaccinated people 18 years and older starting at least six months after the previous dose, The Wall Street Journal reported. The booster, health authorities have said, may help extend the protection conferred by immunization, and help fight contagious variants such as Delta.

The Food and Drug Administration’s approval for an extra dose for all three Covid-19 shots being administered in the U.S.—those manufactured by Pfizer Inc. and partner BioNTech SE, Moderna Inc. and Johnson & Johnson—is expected starting in mid-September, when health authorities said boosters would become available.

The FDA had already authorized the additional shot for certain people with weakened immune systems. Here is what we know and don’t know about the need for boosters.

What is a booster shot?

It is the same dose as given in the two-shot regimen. The extra dose mobilizes your body’s immune system defenses further to protect against Covid-19, especially variants such as Delta that are better at eluding vaccine-generated protection. Pfizer and partner BioNTech said early testing indicates a booster shot given at least six months after the second vaccine dose produces antibody levels five to 10 times higher than after two doses. Johnson & Johnson said in August researchers found antibody levels increased ninefold among people who received an extra dose of its single-dose vaccine, compared with one month after they received a first dose.

Should I get a booster shot?

If and when the FDA authorizes the extra shot, many people should consider getting it, some doctors and health authorities say. The additional dose may bolster a person’s immune defenses against Covid-19. Driving the recommendation for boosters, federal health officials said, were several studies indicating the vaccines lose their protective powers against mild to moderate disease over time and may not work as well against the Delta variant as they did against the previous strains. The data aren’t definitive, but the health officials said they decided to support boosters given Delta’s spread and because it looks like the vaccines may lose effectiveness against severe disease.

It wouldn’t be unusual for a vaccine to lose protective power over time. Although some vaccines, such as the one for measles, offer lifelong protection against a virus, other shots don’t. The vaccines for tetanus and diphtheria require a booster every 10 years, for instance, and women are supposed to get the whooping-cough vaccine each time they are pregnant, according to the U.S. Centers for Disease Control and Prevention’s vaccine recommendations.

An extra Covid-19 vaccine dose could mobilize more antibodies against the coronavirus, helping maintain a strong level of protection. Yet the evidence supporting an additional dose isn’t definitive. The immune system is complicated, involving more than antibodies. Other studies are still under way evaluating any benefit from an extra dose.

In Israel, where the country began offering boosters to people over 60 in July, early data suggests that a Pfizer booster dose can significantly improve immunity among people in that age group. The booster dose, the data indicated, reduced risk of infection in people 60 and over by 86% and against severe infection by 92%.

A key factor behind U.S. government support for boosters is the spread of the Delta variant. Some studies suggest the vaccines, while still highly effective against Delta, don’t work as well as they did against the original virus. An added dose could also help bolster people’s immune defenses against Delta, though that also hasn’t been conclusively shown.

People with weakened immune systems may stand to benefit most from the additional dose. Shots are already available for some of these people, known as immunocompromised. Those eligible include people who have gotten an organ transplant or are taking a drug that weakens a person’s immune response.

Where can I get the booster shot?

Getting the booster will be similar to getting the initial course of vaccination, federal health officials said. The boosters will be available at the roughly 80,000 vaccination sites across the country, including pharmacies, U.S. coronavirus response coordinator Jeffrey Zients said. He said the extra dose will be free to everyone regardless of immigration or health-insurance status.

Under the Biden administration’s plan, people 65 years and older and individuals in chronic-care facilities are expected to get boosters starting Sept. 20, along with health workers and anyone else who received their last dose six months earlier. U.S. health authorities said they are making arrangements for residents of nursing homes and other long-term-care facilities to get an extra dose at the sites. Immunocompromised people who are currently allowed to receive boosters are suggested to consult their doctor but can get them wherever vaccines are administered.

Why at least six months after vaccination?

Data from vaccine manufacturers and other countries under review by the FDA is based on boosters being given at six months. Protection from these vaccines has been holding up well, even against the highly infectious Delta variant, by preventing severe illness in most people. Yet the protection they provide drops over time, the authorities said, especially as the Delta variant has spread and even against mild and moderate disease. Pfizer said in July that efficacy of the vaccine protecting against symptomatic disease dropped every two months, to 84% after six months from a peak of 96% within two months of vaccination. To maximize the protection, the authorities had previously said it was best to give people a third dose eight months after they got their second dose, even though the data aren’t definitive. “With Covid-19, if you wait for something bad to happen before you respond to it, you find yourselves considerably behind your real full capability of being responsive," said Dr. Anthony Fauci, the Biden administration’s chief medical adviser and director of the National Institute of Allergy and Infectious Diseases. “Better stay ahead of it than chasing after it."

Only Pfizer’s vaccine has been fully approved by the FDA, for those 16 and older, so far. Moderna has emergency authorization for people 18 and over for its vaccine and has filed for full approval, which is expected in about three months, the Journal reported. The J&J vaccine is authorized for emergency use in people 18 and older and the company has said it plans to file for approval later this year.

I got Johnson & Johnson’s vaccine. What does this mean for me?

The FDA has been weighing whether adults who received Johnson & Johnson’s single-dose shot will also need another Covid-19 vaccine shot. It is likely this population will also need booster shots, according to U.S. health authorities. The company said in August that a second dose of its Covid-19 vaccine was found in a study to generate a strong immune response, justifying a booster shot.

“The single-dose vaccine is still highly protective, and we know that—that is not diminished, but now we also know that a second dose given at six months boosts immune responses substantially," said Dr. Dan Barouch, who contributed to the development of the J&J vaccine.

Why wouldn’t Covid-19 immunity last?

Studies suggest and many researchers say the immunity provided by Covid-19 vaccines will wane over time.

The vaccines work by generating neutralizing antibodies, which prevent the virus from entering cells and replicating.

Pfizer has said that antibody levels start to decline from their earlier peaks about eight months after the second dose. After a third shot, antibody levels were up more than five times among people ages 18 to 55 and more than 11 times in people ages 65 to 85, compared with two doses, according to Pfizer’s data.

Even with reduced antibodies, vaccines are protecting against severe disease, according to researchers and published research. That is because the vaccines help other immune-system weapons: the T-cells that hunt down infected cells and destroy them, and memory B-cells, which circulate in the blood and help churn out antibodies upon detecting a virus. Both are likely helping prevent severe disease, according to researchers.

What about people with weakened immune systems?

The FDA has already authorized the additional dose for certain people with compromised immune systems. Research shows that immunocompromised people are more likely to get severely ill from Covid-19, are more likely to transmit it to household contacts and more likely to have breakthrough infections. The FDA, in reaching the decision to authorize boosters for the immunocompromised who had gotten organ transplants or have conditions with similar weakened immune levels, noted recent data from Moderna showing a third shot of its vaccine helped increase antibody levels in recipients, a person familiar with the deliberations told The Wall Street Journal.

The immunocompromised include transplant recipients, some cancer survivors and people living with HIV; their weakened immune systems make them less responsive to vaccines, which stimulate the immune system to provide protection. The elderly also tend to have weaker immune systems and they are also likely candidates for boosters. France and Israel are already giving a third shot to some at-risk people. However, the World Health Organization has called for a halt on boosters until at least the end of September, citing an urgent need to vaccinate the rest of the world.

Is it safe for me to get a booster shot from a different vaccine brand?

For immunocompromised people who already are authorized to get a third messenger RNA dose, the CDC says they should try to get the same type of vaccine as their first two shots but can mix and match if they have to. Mixing and matching is under study right now.

In June, NIAID, which is part of the National Institutes of Health, started a study looking at whether mixing and matching vaccines and boosters could prolong immunity and better protect against variants. One thing the study will explore is the best combination of shots. It may be that getting a vaccine from one manufacturer and a booster from another might actually produce stronger protection, researchers say. The ability to mix and match might also simplify the logistics of giving people boosters.

Will boosters better protect against Delta or other variants?

Researchers say the current vaccines appear to work well against variants of concern that have emerged so far. Yet they may not work as strongly against newer variants as they do against earlier ones. For that reason, people may want booster shots to ensure they get the fullest level of protection possible against the variants. And they would want a third shot if any variants emerge that prove better able to evade current vaccines. Drugmakers are working on shots targeting variants.

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