The first results looked at neutralizing antibodies, which are the specific antibodies that stop the virus and protect you from disease. All of the booster shots stimulated a neutralizing antibody response, but there were differences. Those who received the Moderna vaccine for their first two doses and Moderna as a booster had the highest antibody levels. Second place went to people who received two doses of Pfizer, followed by Moderna.
But it’s important to note that small study groups weren’t designed to compare which injection was best, and early studies used a full dose (100 micrograms) of Moderna, not the half dose that has been approved. It is possible that the differences between the study subjects led to the difference in the results. And while the difference in antibody levels looks impressive, it’s probably not that significant in terms of protection in the real world.
The biggest differences in antibody levels were seen in Johnson & Johnson recipients, who showed a fourfold increase in neutralizing antibodies after J. & J. booster, but was multiplied by 76 after the Moderna recall and multiplied by 35 after a Pfizer recall.
Does this mean that if I had Johnson & Johnson I should definitely switch to Moderna or Pfizer?
Not necessarily. For J. & J. recipients, who would have initially received a single dose, there is another study to consider. This included 30,000 people and looked at overall protection against the coronavirus. This study found that a second dose of J. & J., At least two months after the first, resulted in 94% protection against mild to severe cases of Covid-19.
What’s intriguing about the Johnson & Johnson vaccine is that it appears to trigger a different part of the immune system, stimulating not only neutralizing antibodies but also T cells, possibly resulting in longer lasting protection. The NIH study will eventually examine the response of T cells following the different booster dose combinations, but data is not yet available.
So how do I decide which one to choose?
All booster shots stimulate the immune system, so the answer about the shot depends on your priorities and your personal risk. Here are a few examples to help you decide.
Talk to your doctor: Depending on your personal health condition – whether you have underlying health conditions, have blood clots or heart problems, or have been treated for cancer – your doctor may have an opinion on which vaccine is best for you. Different vaccines, for example, have different possible side effects.