The group observed that at the same time as administration of a second dose at 16 weeks did not significantly enhance antibody responses among individuals who were infected before the primary dose, it notably improved these responses among infection-naive individuals. Andres Finzi from the CHUM Research Centre in Quebec, and associates say the findings should help to relieve concerns that an extended period of time between doses might have an effect on the efficacy of vaccination. “Little is known about vaccine-elicited immune responses with longer dose intervals,” says Finzi.
What did they find?
In the covid-naïve group, immunization evoked antibodies with weak neutralizing activity, however, strong Fc-mediated functions three weeks following the primary dose.
These responses declined over the subsequent weeks. However, administration of a second dose sixteen weeks later significantly improved these responses.
Several researches have proven that vaccinating formerly infected individuals elicits strong antibody responses. In agreement with these studies, the researchers observed that the primary vaccine dose triggered strong humoral responses among the previously infected contributors that remained relatively stable over time.
However, a second dose administered 16 weeks later did not especially enhance any of these responses. The group says this finding shows that previously infected people reach peak immunity following the first dose of Pfizer, proving that a second dose could possibly be delayed beyond sixteen weeks in this population group.
Changing the period dose should be considered:
The researchers suggest that bringing the COVID-19 pandemic to an end will require rapid vaccination of the global population, including in countries where vaccines are uncommon. “Modifying the interval at which the two doses are administered might be an important factor to take into account,” the researchers indicate.