At this point, one thing about the pandemic is clear: The COVID-19 vaccines, even when followed by a booster, aren't going to stop the coronavirus or provide long-term protection from infections. Right after the third shot " the booster " antibodies rise up quickly. But then about a month later, they begin to decline. As a result, protection against infection drops down to about 50% three months later. So the question is: Should you get a fourth dose to beef up protection again? A preliminary study from Israel ... suggests that for the general population, the answer is likely no. A fourth shot of the same vaccine " in this case Pfizer-BioNTech or Moderna " offered very little extra protection against infection compared with only three shots. "Not a third dose, not a fourth dose, not a fifth dose will do anything to stop infections [long term]," says Dr. Gili Regev-Yochay, an infectious disease specialist at Sheba Medical Center in Tel HaShomer, Israel, and lead author of the new study. Regev-Yochay and her team gave about 300 health care workers a fourth shot, either Pfizer or Moderna. And then they looked to see if those people were less likely to become infected while working at Sheba Medical Center, compared with about 400 health care workers who had received only three shots. The extra dose reduced the risk of an infection by only about 10% to 30%, Regev-Yochay and her team report. The extra dose also didn't appear to activate T cells, which are critical for clearing out a future infection.