Salvador Iborra
Immunologist
In principle, accelerating the third dose would not be harmful for people who, having received the full course, have been infected with the virus.
Both the EMA and the CDC recommended giving a booster dose of Comirnaty to people over 18 who have received a second dose at least 5-6 months ago, and that seems a reasonable period.
If we have been vaccinated and infected, the virus will have acted as an extra booster dose unless the infection was immediately after vaccination, between 1 and 5 days. Therefore, it would be equally advisable to wait 5 or 6 months, which is the period in which it was seen that vaccine efficacy decreased and could be recovered with the booster.
It is necessary to space the time between doses sufficiently, although it is true that almost all studies have focused on the separation between the first and second dose, which was recommended to be between 3 and 4 weeks (Pfizer/Moderna). A distinction should be made between the time interval between the first and second dose, and the interval between the second dose and the booster dose.
A second dose is essential to increase the immune response in quantity (expanding the number of B and T lymphocytes generated in the first immunisation) and in quality (the second dose helps the B lymphocytes to mature their affinity for the first dose).
lymphocytes to mature the affinity of their antibody response). This response declines over time to save energy and respond to other pathogens. Therefore, the booster dose can help to ensure that this decline does not lead to a significant reduction in vaccine efficacy.
If we do not wait long enough, we will not improve the immune response provided by the infection, because normally the number of lymphocytes and the amount of circulating antibodies do not decline so quickly (in 3 or 4 weeks).