Why Covid-19 Vaccine Boosters May Be More Important Than Ever

Fewer than half of eligible Americans (only about a third of the total US population) have received a first booster dose, according to the US Centers for Disease Control and Prevention. Only about More than 10 million people have received a second booster, which is authorized for people 50 and older, along with those 12 and older who are moderately to severely immunocompromised.

The CDC encourages people to be “up to date” on their COVID-19 vaccinations, including receiving boosters at the appropriate time, but still defines a person as “fully vaccinated” if they have received at least their initial vaccination. . vaccination series.

But this week, a senior Biden administration official was more blunt: All adults need a third shot.

Vaccination is the best way for people to protect themselves against covid-19, and protection is most effective with at least three injections, the official said.

Getting more Americans to protect themselves against Covid-19 could make a big difference when it comes to the number of cases, according to Dr. Peter Marks, director of the US Food and Drug Administration’s Center for Biological Evaluation and Research. The US told the American Medical Association on Monday that it is “a little worried” about the direction of the covid-19 pandemic.

“It’s really important that we try to get half, or a little more than half, of Americans who have only gotten two doses to get the third,” Marks said. “That can make a difference in the future, and it can make a difference in particular now that we are entering another wave of Covid-19.”

The current rising covid cases are nothing like what the US saw with the initial Omicron surge, but as of Monday, the US is averaging 71,577 new cases per day, according to the University JohnsHopkins.

Currently, case rates are highest in the Northeast region of the US, where booster uptake is best. Nearly half the population of Vermont is fully vaccinated and boosted, along with more than 40% of the population of Maine, Rhode Island, Connecticut and Massachusetts, according to CDC data.

But cases are also starting to rise in the south, where less than a quarter of the population is fully vaccinated and boosted. In North Carolina, Alabama, and Mississippi, fewer than 1 in 5 people have received their booster shot.

Who receives, and who does not, reinforcements

Everyone over the age of 12 in the US is eligible to receive a booster dose. Only the Pfizer/BioNTech vaccine is available as a booster for adolescents ages 12-17.

Adults who were initially vaccinated with the mRNA vaccine are eligible to receive a booster dose five months after the initial series. People vaccinated with Johnson & Johnson are eligible for a booster dose two months after their first injection.

Who is eligible for second Covid-19 booster shots and when to receive them

CDC data shows that booster consumption is higher in older age groups in the US, consistent with broader vaccination trends. But nearly 2 in 5 people age 65 and older, and more than 3 in 5 adults overall, don’t have any of their booster shots.

People who get three doses of an mRNA vaccine have a relatively low rate of urgent care visits and Covid-related hospitalizations compared to those who get just two doses, studies have shown. Even with the more infectious Omicron variant, a booster seems to protect against more serious diseases.

Scientists are still trying to determine whether younger age groups would benefit from an additional dose of vaccine. Pfizer and BioNTech have requested emergency use authorization for the age range 5 to 11 years.

“Hopefully, action will be taken in the not-too-distant future,” Marks said.

New research on the fourth dose

A fourth dose of Moderna or Pfizer/BioNTech’s mRNA Covid-19 vaccine, which is already licensed for people over 50 in the US, appears safe and provides a “substantial” boost to immunity at similar or even better levels. than a third dose, according to a study published Monday.

The researchers gave study participants, whose median age was 70.1 years, either a half dose of the Moderna vaccine or a full dose of the Pfizer vaccine in a random selection in January, about seven months after receiving their first booster. . The second booster did not appear to have any significant side effects. The biggest complaints were arm pain and fatigue.

The booster also generated an immune response on day 14 that was greater than that on day 28 after the third dose of the Pfizer or Moderna Covid-19 vaccine.

Children have prolonged covid, too, and it can show up in unexpected ways

When the researchers compared mRNA vaccines, Moderna’s fourth dose seemed to work slightly better than Pfizer’s, but it’s not clear why. Both generated what the scientists considered a “significant change” in protective antibodies. T cell responses were also increased after the fourth dose.

Antibodies are a first line of immune protection that can prevent a virus from infecting cells. The T cells arrive later and destroy the infected cells. T cells cannot protect against minor infections, but they can prevent infections from progressing to serious illness.

“Fourth-dose Covid-19 mRNA booster vaccines are well tolerated and increase cellular and humoral immunity,” the study says. “The maximal responses after the fourth dose were similar to and possibly better than the maximal responses after the third dose.”

His symptoms of the virus were minor.  Then they had a lot of Covid.

The study also showed that some people who had higher levels of antibodies before the fourth dose of the Covid-19 vaccine had only a “limited” booster. Those with a history of COVID-19 infection had a similar limited response. The authors say this suggests there may be a ceiling or peak response that may come with a fourth dose of vaccine.

The study did not specifically look at neutralization of the Omicron variant.

Two earlier studies from Israel showed that Covid-19 hospitalization and death rates could be reduced with a fourth dose of vaccine given at least four months after the third dose. The reduction in hospitalizations and deaths persisted over time with this fourth shot.

New generation of vaccines and boosters

Marks hopes that the next generation of COVID-19 vaccines, which he predicts will arrive in a year or two, will be even better at protecting people against “the full range” of COVID-19 variants and provide a stronger immune response. solid.

The FDA’s vaccine advisory committee will meet in late June to review data on vaccines, including monovalent vaccines (which would target a single variant) and bivalent vaccines (which could target the original strain of the virus plus another).

“It’s a bit of a challenge here because we don’t know how much further the virus will evolve in the next few months,” Marks said. “But we don’t have a choice, because if we want to produce the hundreds of millions of doses that need to be available for a booster campaign, we have to start in early July or even earlier to get those kinds of numbers.”

The FDA committee may also discuss whether an additional booster should be recommended in the fall for the general population or for target groups, Marks said.

Some doctors have said they have heard from patients who want to wait to get a booster to get better coverage for the winter. Marks said waiting to get a booster is a bad idea, especially if those people haven’t recently had Covid-19.

“Why? Because it’s going to be four or five, six months before we get to when he gets his next booster,” he said. “You’re talking about having several months there at risk.”

Even with a predicted rise in the fall and winter, cases are on the rise now, and those who have received just two injections of mRNA are vulnerable.

“Instead of being casual about it,” Marks said. “I urge you guys to try and get that third dose to boost immunity just because we have so much covid-19 going around.”

CNN’s Deidre McPhillips contributed to this story.

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