The study in which Dr. De Serres participated is actually a second analysis of clinical data published as part of clinical trials. It's a different way of analyzing the data.
They removed the data from the first seven days of the clinical trial on the basis that it's well known that the vaccine isn't effective yet during that period. Their analysis showed that the effectiveness of the first dose was similar to the effectiveness of the second dose.
However, it should be noted that, in this analysis, the number of participants who received only the first dose was very limited, since this was a two-dose study. The data can be interpreted based on a very small sample.
Nevertheless, as I said earlier, if we look at the real-world data, such as the field data from the United Kingdom, we see a differential effect based on the age of the person who received the first dose. The data is perhaps justified based on the field data for younger people. I'm concerned about the data for older people. It gives us an immunization status, but it doesn't give us any information on the impact of the second dose over the long term or the wait time for the second dose. That's very different.
The study only shows us whether people are starting to develop immunity.