Health officials in the United States plan to offer COVID-19 booster shots to vaccinated Americans to shore up their protection amid the surging delta variant and evidence that the vaccines’ effectiveness is declining, reports the Associated Press (AP).
But why, even after the primary vaccination? The AP explainer clarifies.
It is common for protection from vaccines to decrease over time. A tetanus booster, for example, is recommended every 10 years.
From research findings, the vaccines continue to offer very strong protection against severe disease and death. But their ability to prevent infection is dropping markedly during the delta surge among nursing home patients and others, according to studies the Centers for Disease Control and Prevention of the US.
Already, Israel is offering a booster to people over 50 who were vaccinated more than five months ago. France and Germany plan to offer boosters to some people in the fall. The European Medicines Agency said it too is reviewing data to see if booster shots are needed.
While officials are working to determine when to recommend boosters, the current US plan is for people to get a booster eight months after getting their second shot of the Pfizer or Moderna vaccine.
“There’s nothing magical about this number,” said U.S. Surgeon General Vivek Murthy. Rather, eight months is a judgment call about when vaccine protection against severe illness might fall based on the direction of current information.”
“We put the best minds together in the administration, we looked at the best data that we had. We saw a signal,” Murthy said. “And now we are sharing our assessment with the public.”
The vaccines still work well to prevent severe illness, but have been losing some ground recently against infection.
It’s unclear the exact role that changes in behavior or the more contagious delta variant may be playing. But as delta rose and mask-wearing fell, vaccine effectiveness has fallen.
Dr. Melanie Swift, who has been leading the vaccination program at Mayo Clinic in Rochester, Minnesota, says getting more shots into people who haven’t yet been vaccinated at all is “our best tool, not only to prevent hospitalization and mortality from the delta variant, but to stop transmission.”
Every infection, she says, “gives the virus more chances to mutate into who knows what the next variant could be.”
“People who took the vaccine the first time are likely to line up and get their booster,” Swift says. “But it’s not going to achieve our goals overall if all their unvaccinated neighbors are not vaccinated.”