The study, published in the New England Journal of Medicine, is the latest salvo in the conflict over whether booster doses are needed for healthy adults and whether they should be given out, as the Biden administration plans to do, when so much of the world remains unvaccinated. Several independent scientists said the cumulative data so far suggests that only older adults will need boosters — and maybe not even them.
Vaccination remains powerfully protective against severe illness and hospitalisation in the vast majority of people in all of the studies published so far, experts said. But the vaccines do seem less potent against infections in people of all ages, particularly those exposed to the highly contagious delta variant. What the Israeli data shows is that a booster can enhance protection for a few weeks in older adults — a result that is unsurprising, experts said, and does not indicate long-term benefit.
“What I would predict will happen is that the immune response to that booster will go up, and then it will contract again,” said Marion Pepper, an immunologist at the University of Washington in Seattle. “But is that three- to four-month window what we’re trying to accomplish?” Federal health officials — including Dr. Anthony Fauci, President Joe Biden’s top medical adviser on the pandemic — have justified plans to distribute booster shots by pointing to emerging evidence from Israel and other countries suggesting that immunity from vaccination wanes over time.
The idea has sent some Americans scrambling for booster shots even before they are formally authorised, a step the Food and Drug Administration may take as soon as Friday. But even among government scientists, the idea has been met with skepticism and anger. Two scientists who lead the FDA’s vaccine branch said they would leave the agency this fall, in part because of their unhappiness over the administration’s push for booster doses before federal researchers could review the evidence.
On Monday, an international group of scientists, which included the departing FDA officials, decried the push for boosters. In their review, published in The Lancet, the scientists analysed dozens of studies and concluded that the world would be better served by using vaccine doses to protect the billions of people who remain unvaccinated.
“Our primary goal here in this pandemic was, first of all, to avoid, to end all preventable deaths,” said Dr. Soumya Swaminathan, chief scientist at the World Health Organization and a co-author of The Lancet review. “And since we have the tools to do that very effectively, we should be using it to prevent deaths around the world.” To prevent the virus from morphing into even more dangerous forms than the delta variant — and perhaps into one that evades the immune response entirely — the more urgent need, experts said, is to protect the unvaccinated, both in the United States and elsewhere.
In the new study, the Israeli team collected data on the effect of booster shots, based on the health records of more than 1.1 million people over age 60. At least 12 days after the booster, rates of infection were elevenfold lower and of severe disease nearly twentyfold lower in those who received a booster compared with those who had received only two doses, the researchers found.
The researchers acknowledged that their results were preliminary. “We cannot tell at this point what will happen in the long run,” said Micha Mandel, a professor of statistics and data science at the Hebrew University of Jerusalem.
Mandavilli is a health reporter with NYT©2021