RNA vaccines appear to produce very different antibody levels

We tended to treat Moderna and Pfizer / BioNTech RNA-based vaccines as functionally equivalent. They take the same approach to generate immunity and have a very similar set of ingredients. Clinical trial data suggest that they have very similar efficacy — both in the 95 percent area.

So it’s a bit surprising to see in a paper published yesterday that the two showed distinct antibody responses, showing that Moderna induced more than twice the antibody levels of those who received Pfizer / BioNTech shots. bottom. It is important not to guess too much from a single study, but this was large enough that the results were likely to be reliable. If so, the results serve as a warning that you may not want to base many of our expectations on a relatively crude measurement of antibody levels.

New research

The work itself was very simple. The Belgian medical center was vaccinated staff and wanted volunteers to provide blood samples. Samples were taken both before and 6-10 weeks after vaccination and tested for SARS-CoV-2 peplomer-specific antibody levels at both points. About 700 participants received the Moderna vaccine and about 950 received the vaccine from Pfizer / BioNTech.

Using the data at hand, researchers simply compared levels of anti-spiking antibodies in different groups. One of the findings was that pre-vaccinated people responded much more than other participants, with post-vaccination antibody levels exceeding five-fold.

However, a notable surprise is that the Moderna vaccine responded more strongly than the Pfizer / BioNTech version. For antibody units per milliliter of blood sample, the differences ranged from 3,836 to 1,444, and the confidence intervals did not approach duplication. In other words, it is a statistically significant difference in a large enough sample and may not be a coincidence.

However, there are some caveats. For one, medical centers may have been able to properly store and manage vaccines, but at the end of a complex manufacturing and distribution network, something could have happened before reaching one of the vaccines. It means that there is. clinic. Simple replication allows you to quickly organize this.

What to do with it?

Another important caveat is that the researchers behind the study simply measured the total level of antibody attached to the peaplomer. Only these subsets are called neutralizing antibodies. Neutralizing antibodies attach to spikes in a way that interferes with the ability of proteins to interact with cells to insert the viral genome. Most studies do what this has, as measuring neutralizing antibodies is much more difficult.

However, technically, it is possible that both vaccines produced similar levels of neutralizing antibodies, despite differences in total antibodies. Something else can be solved with additional research. This is consistent with a generally similar level of protection for vaccines. Correlates with neutralizing antibody levels..

While waiting for the data to help organize this, it is worth considering that the decision may be a little over-focused on antibody levels. Currently, the debate about the need for boosters is based in part on the fact that antibody levels decline over time, which is a shift from a response to an active infection to a functional immunological memory of that infection. This is a normal result.And the effectiveness of boosters is partly based on the fact that it restores high levels of antibodies-whatever it is. should do it It occurs when immunological memory cells are activated by re-exposure to peplomer.

As with these new results, these results need to be addressed with caution, as we do not fully understand how these changes in antibody levels correlate with protection.

JAMA, 2021. DOI: 10.1001 / jama.2021.15125 (((About DOI).