Why Covid-19 vaccine recalls may be more important than ever


With waning immunity and a coronavirus that seems to become more contagious with each new variant, the Biden administration predicts that up to 100 million more people could contract Covid-19 in the fall and winter. This estimate makes it crucial that as many people as possible receive booster shots of the Covid-19 vaccine, experts say. And if you’re eligible, now’s a good time to get a second reminder.

According to the US Centers for Disease Control and Prevention, less than half of eligible Americans – only about a third of the total US population – have received a first booster dose. Only about 10 million people have received a second booster, which is permitted for people 50 and older, as well as those 12 and older who are moderately to severely immunocompromised.

The CDC encourages people to be ‘up to date’ on Covid-19 vaccinations – which includes getting reminders at the appropriate time – but still defines a person as ‘fully vaccinated’ if they have received at least their first round of vaccinations.

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

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

Getting more Americans strengthened against Covid-19 could make a big difference to numbers, says Dr. Peter Marks, director of the U.S. Food and Drug Administration’s Center for Biologics Evaluation and Research. of cases. He told the American Medical Association on Monday that he was “a little concerned” about the direction the Covid-19 pandemic is taking.

“It’s really important that we try to get half — or a little more than half — of Americans who only got two doses to get that third dose,” Marks said. “It can make a difference moving forward here, and it can especially make a difference now that we are entering a new wave of Covid-19.”

The current surge in Covid cases is nothing like what the US saw with the initial Omicron surge, but since Monday the US has been recording an average of 71,577 new cases per day, according to the Johns Hopkins University.

Case rates are currently highest in the Northeast region of the United States, where the booster intake 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 beginning to rise in the South, where less than a quarter of the population is fully vaccinated and boosted. In North Carolina, Alabama and Mississippi, less than 1 in 5 people received their booster.

In the United States, anyone age 12 and older is eligible for a booster dose. Only the Pfizer/BioNTech vaccine is available as a booster for adolescents 12 to 17 years old.

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

CDC data shows that booster uptake is higher in older age groups in the United States, consistent with broader trends in vaccination. But almost 2 in 5 seniors aged 65 and over – and more than 3 in 5 adults overall – do not receive any of their booster shots.

People who receive three doses of an mRNA vaccine have a relatively low rate of urgent care visits and Covid-related hospitalizations compared to those who received only two doses, studies have shown. Even with the more infectious Omicron variant, a booster appears to protect against more severe disease.

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

“This will hopefully be implemented in the not too distant future,” Marks said.

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

Researchers gave study participants with a median age of 70.1 years a half dose of the Moderna vaccine or a full dose of the Pfizer vaccine during a random selection in January, about seven months after receiving their first reminder. The second booster didn’t seem to have any major side effects. The main complaints were arm pain and fatigue.

The booster also generated a higher day 14 immune response than day 28 after the third dose of the Pfizer or Moderna Covid-19 vaccine.

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

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

“Fourth-dose Covid-19 mRNA booster vaccines are well tolerated and enhance cellular and humoral immunity,” the study states. “The peak responses after the fourth dose were similar to, or even better than, the peak responses after the third dose.”

The study also showed that some people who had higher antibody levels before the fourth dose of the Covid-19 vaccine had only a “limited” recall. 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 can come with a fourth dose of vaccine.

The study did not specifically address the neutralization of the Omicron variant.

Two previous studies from Israel have shown that hospitalization and death rates from Covid-19 can 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 vaccine.

Marks hopes the next generation of Covid-19 vaccines – which he says will arrive in a year or two – will be even better at protecting people against “the full variety” of Covid variants and provide a more robust immune response.

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

“It’s a bit of a challenge here because we don’t know how far the virus will evolve over the next few months,” Marks said. “But we have no choice, because if we want to produce the hundreds of millions of doses that need to be available for a recall campaign, we need to start early July or even earlier to get those kinds of numbers.”

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

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

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

Even with an expected fall and winter surge, cases are on the rise now, and those who have received only two mRNA injections are vulnerable.

“Rather than being casual about it,” Marks said. “I urge them to try and get that third dose to boost immunity just because we have a lot of Covid-19 circulating.”


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