Today we’re looking at a published data set from last week that evaluated the similarities and differences between antibody titers after 1 and 2 doses of mRNA vaccine in both individuals who had had Covid prior (seroposotive) and those who had not (seronegative). It is a limited study, with only 110 individuals and very little collected data after dose 2. Both Pfizer and Moderna were included in this study. No details about length of time post-covid recovery for seropositive individuals.
Several important points you can draw from the main paper figure.
1. The seropositive participants had a moderate level of immunity before dose 1 of the vaccine.
2. There is big jump in antibody titer in the 5-8 day post-dose 1 time period.
3. Dose 2 appeared to have a very low impact on antibody titer in originally seropositive participants, while it increased titer (~3x) in originally seronegative participants.
4. Originally seropositive participants have much higher antibody titers (~6x) after vaccination than originally seronegative participants.
5. (Slide 2) While injection-site symptoms were about the same between the two groups, originally seropositive individuals showed a higher frequency of systemic symptoms after vaccination.
As usual, more data is needed to draw formal conclusions but this highlights the potential for a single dose of vaccine to be protective in individuals who previously had Covid.
Posted on Instagram on April 12, 2021.