People who have been fully vaccinated with Pfizer shot have about 10 times higher antibody concentrations than those who have received inactivated vaccines like China’s CoronaVac, according to a new study published in The Lancet.
While measurement of antibodies may not be enough when it comes to mediating Covid-19 immunity, the researchers said “the difference in concentrations of neutralizing antibodies identified in our study could translate into substantial differences in vaccine effectiveness”.
The researchers mentioned that the study did not include data on other potential correlates of protection such as T cells or anitbody-dependent cellular cytotoxicity antibodies.
For the study, the team enrolled 1,442 healthcare workers from public and private hospitals and medical clinics in Hong Kong and collected blood samples from them during three intervals — before vaccination, after the first dose, and after the second dose.
Among the 93 fully vaccinated participants or healthcare workers in the trial, for whom they had complete data on antibody concentrations, 63 have received both doses of Pfizer vaccine while 30 others have been vaccinated with CoronaVac.
The researchers noted that the antibody concentrations for the 63 Pfizer recipients rose “substantially” after the first dose and again after the second, while the 30 CoronaVac recipients showed “low” amounts of antibodies after their first shot, and “moderate” amounts after the second.
The average antibody levels of a subset of 12 Pfizer recipients, after the second dose, stood at 269, which was 10 times higher than those depicted by 12 participants in the CoronaVac group, which stood at 27.
As we reported earlier, the United Nations Children's Fund (UNICEF) delivered 2,000,040 doses of mRNA Covid-19 vaccine manufactured by the American company Moderna, to Ukraine.