Early data from Israel suggests that a fourth dose of either the
Pfizer/BioNTech or Moderna coronavirus vaccine can boost antibody levels above
those seen after the third dose, but that this may not be enough to prevent
breakthrough infections caused by the Omicron variety.
"These are preliminary findings. This is before any publication, but we're sending it out because we recognize the public's need for as much information as possible about the fourth dose "During a virtual news conference on Monday, Dr. Gili Regev-Yochay, director of Sheba Medical Center's Infection Prevention and Control Unit, discussed the findings with reporters.
"We've been following up on the Pfizer vaccine for two weeks, and the Moderna vaccine has only been followed up on for one week at this point. And what we notice is that two weeks after receiving the Pfizer vaccine, there is an increase in the number of antibodies and neutralizing antibodies — a significant increase. It's even a tad greater than after the third dose "According to Regev-Yochay. "However, this will most likely be insufficient for the Omicron."
Sheba Medical Center began testing a fourth dose of the vaccines in healthy persons in December, ahead of the introduction of the additional booster shot to at-risk patients. This is the first study of its sort.
A total of 154 health care workers received a fourth dosage of the Pfizer/BioNTech vaccine, 120 received a fourth dose of the Moderna vaccine, and a control group received no fourth doses.
Although the researchers detected an increase in antibodies among individuals who had fourth doses, Regev-Yochay believes that the amount of antibodies required to defend against Omicron infection "is probably too high for the vaccine, even if it's a good vaccine." Despite this, she stated that those who received the vaccine had somewhat fewer infections than those who did not.
Regev-Yochay stated that there was no significant difference between individuals who received the Pfizer/BioNTech dose and those who received Moderna.
"I believe that allowing the fourth vaccine to vulnerable groups was probably the right decision," she stated. "It may provide some advantage, but not enough to justify the decision to give it to the entire population".